This got buried in the pissing match over at: http://www.pirate4x4.com/forum/showthread.php?s=&threadid=32493

Let's assume that:
* you are fully locked
* your locker stays engaged
* your driveshafts and transfer case hold
(don't get me started on whether a Detroits is the same as a spool without power to the pinion :D )

I can throw out a bunch of information about effective gear ratio, brake ratio, and rotor speed, but I don't know firsthand how this works with two pinion-mounted brakes. I do know how this works with wheel-mounted disk brakes, and I understand how increasing brake swept area helps on an exponential scale...

But I am wondering whether pinion-brake systems can be very functional in the real world, especially on the street.

At first glance, with the rotational mass of everything 'outboard' of the pinion (that's the diff, the axle shafts, the 20" steel wheels, and the 53" billion-ply military tires), I can't see how a teeny 4-bolt rotor and two-pot caliper could even start to hold back 2 tons worth of trail rig, not even if there were two of 'em, one on each pinion.

Randii (who likes a brake on each wheel, thankyouverymuch!)

In that other thread....

Pete (pcorssmit) posted:
I've asked how overheating could NOT be a problem on a few posts, and this is the first one I've seen where someone actually said something about it. Yes, the brakes will have plenty of power due to the gear reduction, but you still have to dissipate the same amount of energy. You're trying to stop the same or more weight (as the rig w/one ton axles) with 1/4 the brake area. I don't see how they could keep from overheating.

-----------------------

Then CJ Lagos posted
I'm bothered by the fact that people are having their pinion discs get really hot. Think about it, your giving your brakes roughly a 7x multiplication. There should be a whole lot less force needed to stop the axle with that one caliper and the reduction than two calipers at the wheels. What I think might be happening is people are generally using smaller components. I'm shooting for 1/2ton chevy stuff, I don't think that will get over worked. g

I see pretty small components in use, maybe that is part of the problem, but I dunno.

Brakes are pretty simple things, really -- they disippate kinetic energy as heat. The differential gears offer mechanical advantage, but that energy still has to turn into heat!

Food for thought....

Randii

heh, we're actually discussing things close to this on anther board @ the moment. I have a friend that ran a pinion brake on the rear of the truck for a while. Stopped fine, but ate pads up quick. He was using a F150 caliper & rotor.

Well then, why not two calipers per rotor? Or, why not run twin rotors with one caliper per rotor?

Randii,

I think you're right on. There's a great book from HP books (The Brake handbook) that has all the info and formulae to prove it. But your instincts are correct.

Brakes convert energy, gearing has NOTHING to do with it. Consider the places where braking is the most critical, like F1 cars and Rally cars...thay have HUGE rotors at the wheel with multiple calipers on each. Shoot, those little lightweight Rally cars have 15 inch rotors!!!

I would think a pinion only brake would be pretty damn useless / scary on the street.

Of course, that's just based on theory. Any of the big boys wan't to prove me wrong, please post a clip of you doing 70mph than locking them up under a full panic stop.

Now - if you never do anything but back of a trailer and crawl at <10mmoh, that makes a HUGE difference.

food for thought
on the downside:
not as much brake to dissipate the heat

require a proper locker to equilize braking

unlocking hubs are a nono

if the shafts break you lose brakes

may not be legal where you live anyways.

on the upside
you have a gearing advatage on the tires that increases
braking power compensating for large tires

the disk is spinning faster so it can move more cooling
air thru the vents, also it is mounted in an area that
sees more airflow than inside a rim and tire

I plan to try this out on my d70's when I set em up, seems cheaper than putting the disks on the hubs.

Well then, why not two calipers per rotor?
That does not increase the disk's ability to shed heat. It increases the amount of friction material applied, but IMHO 4-pot calipers or the like from a high-performance car would get you there more easily.

Or, why not run twin rotors with one caliper per rotor?
This could work, but remember, the area of a circle goes up on a squared relationship relative to radius, so fitting a larger disk makes good sense, and using a vented (mebbe even drilled) rotor makes even more sense.

Trimming the radiator shroud to duct air could really help the front disk on the trail, but these are all band-aids to serious on-road heat. As BV pointed out, this may not matter for trails, but I have yet to see a production pinion service brake on the highway.

Pinion brakes seem to me to make sense in the same fashion that t-case brakes make sense -- as emergency brakes, but not as service brakes.

Mebbe you Rockwell boyz should be running drag strip drogue chutes. :flipoff2:

Randii

Originally posted by mytzlflick
the disk is spinning faster so it can move more cooling
air thru the vents, also it is mounted in an area that
sees more airflow than inside a rim and tire



Maybe it eats more pads because the rotor is spinning 6x faster than one on the wheel would be. It might be eaiser to stop with all that gear multiplication if it wasn't spinning that fast. Just thinking.

The guys I've talked to running the pinion brakes say they stop really well. Im wondering about using two calipers per rotor, I might do that, that's a good idea.

CJ

probably eats pads becuase twice the overall force is required on a single disk. if you run one ton disks I would imagine more sucess as they are disigned to stop a lot more weight in the first place. and yeah i imagine that kind of surface speed would be a problem. if you run highway speeds with 7.17 gears your disk would think it was running 350mph, probably a little outside the average design parameters of a brake pad.

I would never use a pinion brake setup on the highway for the simple reason that there is no mechanical ebrake. I would want at least one braking system at the last possible point of failure-the wheel. However, my rig is trail-only, so I feel that pinion brakes, coupled with a t-case e-brake will be more than satisfactory.

what about 2 roters per driveshaft. one on the tcase output and one on the pinion (assuming rockwell).

i have thought about trying to rig something like this under my motorhome for supplemantal braking to the rear wheels for thoes long down grades...totally separate system with its own pedal etc..

Seems like the guys running Rockwells and the need for pinion brakes are not real worried about heat buildup...


I mean seriously - for normal trail use, just how hot are your brakes gonna get? :confused:

Yea - it seems the deciding factor is whether the rig would ever be street driven. Imagine, you panic stop, and the tires grab and lock, but the U-joint you hadn't noticed was wearing lets go under the stress, now your "brakes" are firmly holding the shaftt while the wheels spin merrily out of control.



The guys I've talked to running the pinion brakes say they stop really well

CJ - did they quantify "stop really well" at all. As in, stop really well when I'm rock crawling at 5 mph, or stop really well as in a panic brake and swerve manouver at 70 mph in the rain?

Originally posted by DRM
Seems like the guys running Rockwells and the need for pinion brakes are not real worried about heat buildup...


I mean seriously - for normal trail use, just how hot are your brakes gonna get? :confused:


Yup.

However, my rig is trail-only, so I feel that pinion brakes, coupled with a t-case e-brake will be more than satisfactory.
Excellent -- I appreciate the redundancy in that setup. Kudos for planning well... I'd park behind you on the trail any day. :D

There are WAY too many folks relying only on their service brakes, without a functioning emergency brake... and far too few of them park nosed up against something when they stop. Thinking back to that Toyota that swimming in Spider Lake, wouldn't a functioning e-brake have been a good thing?

Randii

I cant post pics until monday
Those will be FUN pictures! I'm imagining a 6-by locked up and sideways. :D

...know that I can lock up 6 tires at any speed the real problem is the brakes work too good...
Yeah, that's proof of part of the issue, but how does the truck handle lengthy braking sessions, like when you are descending a mountain, working turn-by-turn. Engine braking only gets you so far...

I'm not meaning to attack you -- I am honestly curious. :cool: This is great tech!

Randii

I run pinion brakes with my bronco, one on the rear pinion and one on the front of the t. case. It's trailered
The reasons I use them are:
Drum brakes and related hardware weighed 180 lbs. (unimog)
With my axles pinion is 27'' high (unimog, flipped 9'')
Pinion brakes work great at slow speeds.

Using 9'' rotors, 3/8'' thick the rotors would quickly become RED HOT so I'm having Coleman make 1-1/4'' vented rotors.
The pads also wear down fast. (200 mi.)
Using detroits, there is a " clunk" as all the slop is taken out when the brakes are used and they're somewhat jerky
I would never consider pinion brakes for street use.

I'm woundering in street use as a detroit sometimes decided to change lanes under power would this create the same effect under braking with pinion brakes? I'm still gonna try it on my t-case. hey jr do you have to run a flange on the case to mount those or can they go on a normal yoke somehow?

Assuming you forget about the possibility of breaking an axle or the detroit unlocking.

Ok, so you have to convert the energy somehow. brakes convert the energy to HEAT, which on a rockcrawling trail only rig should not be an issue.

Dual calipers will only help if your boiling the fluid, since swept area is not the issue.

Vented rotors will help, ducting cool air to the caliper will help. Gas slots in the rotor would help. Crossdrilled rotors help.

But bottom line the energy that needs to be converted is still the same. The pinion mounted rotor has mechanical advantage, but it has a speed disadvantage, so it will stop really well, might even do it a few times in a row, but those rotors will be glowing red, cooking the pads, the fluid, the pinion seal, etc.

To get the pads to last (and last would be a relative term) you'd have to run a superhard compound, which would take a little to heat up, which is no fun when you need to panic stop right after pulling out of your driveway!

I finished with the rockwells about 2 mths. ago, and have been driving it around. I think the pinion brake is awesome. I am using the boyce kit, which utilizes 1/2ton chevy rotor and caliper. It stop easily with little pedal pressure. On the street, it is more than sufficient for normal driving with just rear brakes, nothing in the front. duing wet weather, it would be a good idea to run in 4hi so the front would stop too. There is a little slop that i can feel in the carrier, but it is not bad.

Also i have open diffs, and someone above suggested that you need a locker to get equal braking, however this is not true. the pinion brake stops the carrier from rotating, so the spider gears can't rotate. If the spider gears can't turn, then neither can each side gear, which means the shafts can't turn. You don't need a locker to get equal braking force...

1 more thing, if you are gonna run a pinion brake, make sure you have a traction arm, or a link-type suspension, because they cause reverse axle-wrap really bad. the more axle wrap you can eliminate, the less slop you will feel in the brakes.

[hey jr do you have to run a flange on the case to mount those or can they go on a normal yoke somehow? [/B][/QUOTE]

I use a drive flange.
I don't know what the flange is from only that it needed to be broached for 32 spline. Jessie from high angle drive line did the work.

I finished with the rockwells about 2 mths. ago, and have been driving it around.
On the STREET? :eek: Glad you don't live near me! One brake on one axle - piped through an open differential, attached to 44" tires? Gads...

Also i have open diffs, and someone above suggested that you need a locker to get equal braking, however this is not true.
Um... it *IS*, in a practical sense. Go jack up one side of your rear end with RWD and the pinion brake engaged. See how it rolls down the driveway? The pinion is fixed, but the spiders can 'unwind' opposite to each other. With your 44" tires acting as flywheels, wheel rotation reversion is not about to happen on the street, so the point may be moot, but I dunno. Go do a test for us if you would -- hammer the brakes at 30mph and let us know if you lay two patches of rubber. Hell, try it in 4WD and let us know if you get 4 skids. If ya wanna get really complicated, try that 5 times in a row, and let us know how much longer the stopping distance is on the 5th try (betcha money it will be longer, my Amigo starts to fade the front brakes on the 5th consecutive HARD decel from 30mph, and I have 4-wheel disks.

Randii

Originally posted by elf_cruiser
I finished with the rockwells about 2 mths. ago, and have been driving it around. I think the pinion brake is awesome. I am using the boyce kit, which utilizes 1/2ton chevy rotor and caliper. It stop easily with little pedal pressure. On the street, it is more than sufficient for normal driving with just rear brakes, nothing in the front. duing wet weather, it would be a good idea to run in 4hi so the front would stop too. There is a little slop that i can feel in the carrier, but it is not bad.

Also i have open diffs, and someone above suggested that you need a locker to get equal braking, however this is not true. the pinion brake stops the carrier from rotating, so the spider gears can't rotate. If the spider gears can't turn, then neither can each side gear, which means the shafts can't turn. You don't need a locker to get equal braking force...


And we wonder why we have all the stupid laws being passed about lifted/modified vehicles...

Pete

Your odds of getting creamed by a cellphoney in a suv are much greater than a trail only rig driving on the hardstand.

I can see how a break on the t-case is out of harms way, and I've candycained both my drive shafts. Does having a rotor slaming into a rock bother anyone else?
And if you drop on it, does it walk you sideways?
If your on a muddy road doing 10 and slam on the breaks (open diff) stopping drive shaft rotation, will the spider gears want to spin the loose tire backwards as you continue going forward?Would a trash lock or anything short of an arb / spool be enough to prevent this?

:confused:I guess I just don't get the whole idea behind a pinion brake. I suppose you could replace the whole braking system with pinion brakes but that doesn't make any sense to me. It does sound like a whole helluva a lot of compromise.
:rolleyes:I thought that the pinion brake was a replacement set-up when you remove the E-brake system and cables.

Let the flaming begin! :flipoff2: :D :flipoff2:

I'm with Tigger on this one.

I've done a couple of 4-wheel disc conversions, both to trucks and 2wd cars, and I can't think of a single reason I'd want to ditch two to four brakes and replace them with a single disc that's seeing four to six times the surface feet per minute at the pad.

Especially when the failure of any one of a large number of components along the way can essentially sever the one brake from the tires.

I can understand wanting to make the truck a little lighter, but I know I'd be down to sawing off more body sheetmetal or holesawing the frame before I ditched any brakes at all.

You want light? Use Wilwood-type aluminum calipers, rotors with spun steel "hats" instead of cast iron, and ditch the power booster.

The ONLY application I'd ever use a pinion-mounted brake is as a purely-mechanical parking/emergency brake.

And I very much doubt that a pinion brake is legal on the street. Or, if it's not now, it will be the minute somebody has a wreck because that one little bitty brake couldn't stop a 5,000 lb truck with 44" tires.

Like horsepower and torque, you can never have enough braking power.

Doc.

Any of you guys ever been to a monster truck show????
if you have you will have noticed that the guys running 5ton Rockwells don't have detroits, usually, but they always stop with all 4 tires. hmmmmmmm....

and, i can lay 2 even patches of rubber, but i haven't tried braking in 4wd on the street, until i get a traction bar for the front, hop hop hop.

Daniel, you are correct about 1 shaft trying to turn the opposite direction, BUT having the tire try to reverse-rotate is going to provide as much stopping power as locking up. The only way you could lose braking force is if you were driving and 1 tire was in an oil slick, or on ice, and the other was not. Then the tire on the oil would spin backwards, but how often can that happen...

also, r the people having trouble with overheating running auto trannies?? cause i have a 465, and with 6.72 gears, i get enough compression braking to slow down for stop signs with out using the brakes until the last second. I have had no overheating problems...

THIS DOES, detroits!
Nooooooooooooo!!!!!

I said... don't get me started on whether a Detroits is the same as a spool without power to the pinion...

It ain't the same!

Randii

Of course, that's just based on theory. Any of the big boys wan't to prove me wrong, please post a clip of you doing 70mph than locking them up under a full panic stop.

so how does this prove brake effenciency?

locking the tires requires one instance of hard brake pressure until the tires break loose, once the tires are sliding no heat will be generated at the rotor/caliper.

I would be much more impressed with controlling speed down a long steep grade without cooking the brakes

I said... don't get me started on whether a Detroits is the same as a spool without power to the pinion...

wouldnt the drag on the pinion act the same as pressure from accellerating in regards to locker functioning?

Sometimes when monster trucks lock up the brakes one tire does spin backwards. Not that it would do it on the street under normal braking but one could spin back with an open diff.

Originally posted by randii
THIS DOES, detroits!
Nooooooooooooo!!!!!

I said... don't get me started on whether a Detroits is the same as a spool without power to the pinion...

It ain't the same!

Randii

last I checked a pinion brake WAS putting power to the pinion, since it's trying to stop rotation it's appluying force the same as when you back up, or is it just a fluke that I can back my detroited truck uphill, am I supposed to get out and push my truck backwards anytime I want to back up, because the detroits are just supposed to freewheel in reverse? Please tell me some possible causes of the probelem with my detroits causing them to malfunction and allow the truck to back up when it's in reverse, as I might need a few suggestions to give the shop of what to look for when I take it in to make it function correctly. Hell, you better call tractech too, cause they might want to recall all of the detroit lockers, because from what you are saying EVERY detroit locker I've ever seen is malfunctioning, cause everyone I know with a detroit can apply power to them in either direction...

heres one more thought for this, against it actually, forward cut gears in the back are weaker in reverse right? well the brake is applying force the same as being in reverse, brakes can create a lot more force than the engine can, what are the odds of shearing off gear teeth in the rearend?
detroits work the same both ways or they wouldn't work in the normal cut front axle applications witch are always theroretically spinning backwards. I was just woundering if they would cause interesting handling qwirks with that much load applied so suddenly?

last I checked a pinion brake WAS putting power to the pinion, since it's trying to stop rotation it's appluying force the same as when you back up
Dangit, I didn't want to go here.... my point isn't that a Detroit Locker won't lock in either forward or reverse, but that it only does this beyond a certain threshhold... ever watched a Detroit-lockered rig come downhill on slick stuff? There has to be enough power geting sent to that differential or it won't 'lock' -- that's why many folks coast around corners. Slam that brake, and you're good, but ease into it, and it may just take a bit.... that's gotta be pretty entertaining on wet payment, eh? :p

This is yet another reason why I like wheel-mounted service brakes - you don't have to sweat whether the Detroit is gonna lock, whether the ARB is gonna stay pressurized, etc.

am I supposed to get out and push my truck backwards anytime I want to back up
Personally, I'd like to see that. :flipoff2: :D :flipoff2:

Randii

Originally posted by randii
[am I supposed to get out and push my truck backwards anytime I want to back up
Personally, I'd like to see that. :flipoff2: Might make up for some of that been-here-a-whole-year attitude. :rolleyes:

Randii

I'm a fan of having 4 wheel mounted brakes myself too, when my buddy and I get out competition truck done it'll have 4 wheel disks on it's rockwells. I never have realised that there is a "threshold" with detroits for them to lock, mine seem to lock pretty easy, if I try to rotate the driveshaft by hand in either direction the wheels lock right i, maybe I'm not clear on what you are referring to...but we seem to agree that wheel brakes are best, so maybe leaving lockers out of the discussion is best...

BTW I have been reading this board for 3 or 4 years, I just didn't register untill I had some input on a subject...

so how does this prove brake effenciency?

Oh it doesn't not one little bit. But it is an instance of pretty tremendous one-time shock loads developed as you try to stop that 5000lb+ rig turning 44 inch tires at 70 mph.

There's quite a lot of kinetic energy their, and I was just wondering if the sudden load wouldn't shear gear teeth or break driveshaft U-joints.

Plus, it'd be entertaining as hell to see!

Your example is even better...and another part of the whole braking picture.


I remain utterly unconvinced of the safety and apropriateness of pinion brakes on the street. And the example of the guy that uses his granny low to engine brake to an almost stop is an example why i take those with "real world" experince with a grain of salt. Surely, you're not going to downshift to 1st when you're trying to brake from 70mph and swerve at the same time....and if your rig isn;t safe doing this manouver...it shouldn't be on the street.

Cellphoneys...irrelevant argument....as basic as "2 wrongs don't make a right"

Originally posted by CrazyHorse


I'm a fan of having 4 wheel mounted brakes myself too, when my buddy and I get out competition truck done it'll have 4 wheel disks on it's rockwells.

How do you plan to do this? Have you actually looked and figured something out or are you just planning on doing it?

CJ

no clue yet, we don't have the axles to start playing with, but he's a machinist by trade, and is sure that something can be created.

Billavista:
I remain utterly unconvinced of the safety and apropriateness of pinion brakes on the street. And the example of the guy that uses his granny low to engine brake to an almost stop is an example why i take those with "real world" experince with a grain of salt. Surely, you're not going to downshift to 1st when you're trying to brake from 70mph and swerve at the same time....and if your rig isn;t safe doing this manouver...it shouldn't be on the street.


Dude, i never said i used the granny gear to slow down, that is impossible because it's not syncronized. I leave it in 4th(3rd technically) and let the motor slow the truck down, before i apply the brakes. What i mean is that a stick-shift gets more compression braking than an auto, and the whole overheating thing is more likely to happen to those with auto trannies.

also, this is my second vehicle, i don't drive it much faster than 35 mph, or on the highway, and i am very cautious when driving it on the street. after wheeling with the pinion brakes, i think they are great if you are gonna have 44's or bigger, any tire under 40" and it's probably a waste of time.

CrazyHorse, i also thought about this setup, but it would be difficult to do, and you will have to keep the hubs flipped out on a steering version, which i assume you would go with rear-steer. So it may not be possible to do this, and stay narrow, but let us know what you come up with.

later ya'll

Dude, i never said ......

Sorry - piss-poor misquote on my part.....unintended. But I meant the same...you definately rely on engine compression braking. Nothing wrong with that either....any big rig decending the mountain with a full load does too!


And I hear ya on the easy does it, only to and from the junkyard or trail street driving...i do that too. Didn;t mean to sound all "high and mighty" just poiniting out issues as I see them.

If you've got a brain and understand your tool and it's application it's all good.

Thanks, BV

I just got a little defensive...

Anybody thought about the trucks that these trucks came off of? Big, usually overloaded trucks that stop like any other trucks. Hmmmm, dont see them counter rotating tires or needing lockers or spools. If these trucks can stop fine I wouldnt worry about the pinion mounted brakes on the axles. How is your 5k lb rig gonna override brakes that are designed to stop a 20k lb truck?

I can see the overheating issue but the brakes are slowing the pinon speed and then the gearing multplies the braking effects also. Besides a set of high quality pads and/or cross drilled rotors will usually assist the cooling effects.

The pinion brake is something that the crazy 4wheelers add...stock they have gigantic drum brakes at the wheels. You take these off and you'll loose several hundred pounds easy.

CJ

Originally posted by JR
I run pinion brakes with my bronco, one on the rear pinion and one on the front of the t. case. It's trailered
The reasons I use them are:
Drum brakes and related hardware weighed 180 lbs. (unimog)
With my axles pinion is 27'' high (unimog, flipped 9'')
Pinion brakes work great at slow speeds.

Using 9'' rotors, 3/8'' thick the rotors would quickly become RED HOT so I'm having Coleman make 1-1/4'' vented rotors.
The pads also wear down fast. (200 mi.)
Using detroits, there is a " clunk" as all the slop is taken out when the brakes are used and they're somewhat jerky
I would never consider pinion brakes for street use.

sweet set up i hope you did it all yourself nice work!!

Nudge. :flipoff2: Stir, stir.... :p
who'll take my wager?

Originally posted by randii
Nudge. :flipoff2: Stir, stir.... :p
who'll take my wager?


Sir, I have come to the conclusion that you are truly evil :p

what do you want to stir??? a year later and my brake pads look exactly the same as when i installed em. I still love the pinion brake!!!

Originally posted by elf_cruiser
what do you want to stir??? a year later and my brake pads look exactly the same as when i installed em. I still love the pinion brake!!!

Thats cuz you never go wheelin!!:rolleyes: :flipoff2:

Originally posted by The Rockslut
Anybody thought about the trucks that these trucks came off of? Big, usually overloaded trucks that stop like any other trucks. Hmmmm, dont see them counter rotating tires or needing lockers or spools. If these trucks can stop fine I wouldnt worry about the pinion mounted brakes on the axles. How is your 5k lb rig gonna override brakes that are designed to stop a 20k lb truck?

I can see the overheating issue but the brakes are slowing the pinon speed and then the gearing multplies the braking effects also. Besides a set of high quality pads and/or cross drilled rotors will usually assist the cooling effects.

Did you realy want to open your yap about something you know nothing about. These trucks have large drum brakes on them. It's when peps take those brakes off and put pinion brakes on these axles that they're talking about.

It would have been better to keep your mouth shut and have peps think you're a fool, than type this drivel and prove the fact. :flipoff2:

Mine are a year old and look and feel fine. I used regular Auto Zone replacement pads for a Toyota 4 piston caliper.

I use the stock Samurai brake system and it is almost too much braking power. With a power brake system you get the "light switch" effect, either on or off, no modulation. Most people use an aftermarket manual braking system.

I have problems with heat, but I just use mine for trail riding and use engine braking as much as possible if I have to go down a steep grade getting to and from the trail. I have never had any loss of braking from overheating, just that "burnt clutch" smell sometimes.

http://www.rattlerock.com/images/build%20pics/P5110009.JPG

Originally posted by elf_cruiser
The only way you could lose braking force is if you were driving and 1 tire was in an oil slick, or on ice, and the other was not. Then the tire on the oil would spin backwards, but how often can that happen...

(emphasis mine)


Oh dear Lord, PLEASE tell me this was sarcasm..

In case it's not, my reply:
DUDE! How many times does it NEED to happen!?!? Probably only once and you will end up one of the following:
1. dead
2. in jail for killing somebody
3. wrecked your rig
4. scared absolutely sh!tless when you step on the slow pedal and something completely unexpected happens, like a lane change
5. scared absolutely sh!tless when you step on the slow pedal and nothing happens at all

-tom

Thats cuz you never go wheelin!!

Will be soon biatch! I may need yer help next weekend, got any plans?

LandCroozer - I have since welded the carriers F&R - and drove the cruiser daily for about 2 months after my last tow rig was stolen. The situation i described never happened while the rear end was open. Now it's welded so you can relax - but i appreciate the fact that you were worried about my safety!:flipoff2:

I stirred to get more feedback. :rolleyes: Right now, this thread has pretty limited details on actual trail usage, and even less discussion of actual on-road usage (including lengthy braking sessions).

By my count, there's Aceguy, JR and Daniel who weighed-in with serious negatives for pavement use of pinion brakes. AZFord4x4 and KYoder report witnessing negatives first hand, as well. Lotsa theory against, as well, from others (including BillaVista who owns a copy of the Brake Bible). 350Sammy limits his to the trail and still reports the aroma of roasted friction material.

Looks like the best (only?) on-road sampling reported so far is Elf-Cruiser's two months of bumper-to-bumper with the blue-hairs. How many miles, really?

Even anecdotal evidence is in short supply, but there's certainly no shortage at all of some folks assuring others that pinion brakes are safe.... :shaking:

Last time this topic wound down in a bunch of different threads, the clamor in favor of pinion brakes was almost exclusively from the folks who planned to run them... hopefully some of those folks have moved from plan to practice, by now. Anyone else want to weigh in with real-world experience?

Randii

I Called Wilwood and explained the brake situation and they sold me some high speed racing compound pads. Sorry but I still dont have my shit on the trail for some real storys, but I drove Frankies chassis for 6 weeks hard offroad and on road with no ill effects. He uses Wilwood. We both run Detroit Lockers front and rear. The only thing I felt was odd was the delay from the drive train slop. These rigs are NOT going to drive like a stock Toyota truck. Every mod has a good point and a bad one. You just have to decide what you want. I personally love the pinion brake and the Rockwel "FOR MY APPLICATION"
Daniel has directions to help with the slop issue.


Here is the drilled rotor set up that I hope helps cool things at speed.

Canna help ya - I'm just a theory gut myself......but since that's the theory that the big boys use to calculate brakes, i figure it means something. So on that note:

1) I am going to absoloutely scream if i see one more person say "gearing multiplies the breaking effect". That's jibberish - it means nothing. 10 points to the first person who can state the proper name and explanation for what really is going on when people make that statement.


2) Cross drilled and vented rotors DO NOTHING for cooling - and they;re not deigned too. In fact - I hate to tell you, drilling the rotors makes their thermal energy absorbing ability WORSE - exasurb.... exesburbat....exasurba....aaaah hell making worse the problem with pinion brakes. 20 points to the person who can correctly explain why rotors are drilled or vented (grooved).....and no - it's not to reduce weight. (Don't worry Dan - the real reason may be excuse enuff for you, so don't chuck 'em just yet)

I'd have to say, brakes are the single most misunderstood component out there....that's why you see so many people posting problems and complaints.....but once you understand, it's really not that hard.

Originally posted by BillaVista
20 points to the person who can correctly explain why rotors are drilled or vented (grooved).....


To prevent the trapped gasses from hindering pad to rotor contact and cause crashy-crashy-boom-boom?





Anyone considered dual pinion rotors on one or both axles?

Originally posted by DRM
Anyone considered dual pinion rotors on one or both axles?

Why?

Originally posted by 350 Samurai


Why?

Uhhh.... maybe increased surface area and braking force? :confused:

Originally posted by DRM


Uhhh.... maybe increased surface area and braking force? :confused:


You have not driven one of these pinion braked rigs!!:rolleyes:


Bill, I will get to you in a minute.

Dan

As for mileage, I was in Waco, TX when i was daily driving the cruiser, so maybe about 300 miles in 2 mths?? No bumper-bumper traffic there, either. I don't advocate using pinion brakes on your DD vehicle, I'm simply stating that you can get away with it if you have to. And after many trail runs, and flat-towing all over AZ, I still see no pad wear, nor have i experienced any kind of brake fade or over-heating. But, as i stated before the rediculous 6.72 gears help slow the thing down ALOT, so even on the road brakes aren't needed til the very last moment you pull up to a light. When driving on the road, I'm over-cautious and never tailgate because I know i can't panic-stop if i had to. And driving in the rain would be crazy...

That's my real-world experience - As for trail use you can't beat it, aside from the fact that when i lost my brake line i had NO brakes. Heh - I still remember some guy telling me to just pinch the brake line with vise grips, and my brakes would work again. I was like - "no, dude you DON'T get, there's only ONE brake"...

I don't advocate using pinion brakes on your DD vehicle, I'm simply stating that you can get away with it if you have to.
If I saw more of the former advice dispensed, and less of the latter, I'd be a helluvalot more comfortable.

I'd still rather have service brakes at every corner on my own rig, and a separately-actuated e-brake, but for trail used, a coupla p-brakes seems to work...

Randii

Originally posted by BillaVista
.


2) Cross drilled and vented rotors DO NOTHING for cooling - and they;re not deigned too. In fact - I hate to tell you, drilling the rotors makes their thermal energy absorbing ability WORSE - exasurb.... exesburbat....exasurba....aaaah hell making worse the problem with pinion brakes. 20 points to the person who can correctly explain why rotors are drilled or vented (grooved).....and no - it's not to reduce weight. (Don't worry Dan - the real reason may be excuse enuff for you, so don't chuck 'em just yet)

.

Ok Bill, I have alot of respect for all you have done here. But for the life of me why would you say vented rotors would not be for cooling????

From Willwood

Wilwood vented rotors are designed for maximum cooling. The internal vanes pump cool air from the center of the wheel and take heat away from the rotor, allowing rotor temperatures to decrease. Wilwood has designed special curved vane and straight vane rotors to effectively move large volumes of air to rapidly disburse this heat (energy). Specially formulated iron is used to enhance the stability of the rotor, while allowing difficult castings in complex vane configurations to be produced. Wilwood’s proprietary casting techniques are the result of over 20 years of vented rotor research and development combined with actual on-track performance evaluation. All rotors are precision machined to assure surfaces are flat and parallel.

About the drilling and weight????

Wilwood specialty steel rotors are used when rapid thermal inputs occur and material stability is required (i.e. when a dragster must brake from 300 mph). Under such conditions specialty steels are used, often cross drilled to reduce rotational weight.

Now I know I wont be going 300mph and the holes in my rotor wont drop my 635lb axle down to the Camo 60. But I wanted to do it differnet and they just plain look cool.
:cool: :flipoff2:

Dan

p.s. Bill didnt I read somwhere you are a pilot? Im a aircraft mechanic for Fed-Ex. I dont expect as much from pilots.
:flipoff2: :flipoff2:
:D :D

Drilling a "vented" rotor can reduce the cooling affect of the vents. Vented rotors should be sloted to reduce the gassing not drilled.

Originally posted by 70~K5
Drilling a "vented" rotor can reduce the cooling affect of the vents. Vented rotors should be sloted to reduce the gassing not drilled.

Hey man my DRILLED, SLOTTED and VENTED rotors came from Willwood that way. I think THEY know what is going on. No you should not drill your own rotors.
Dan

Dan,

When I said "vented", I really meant "slotted"....the grooved cut in the flat surface (as opposed to ventsing, as in the "vanes" between the 2 sides of the rotor. My mistake with terminology.

So yes - venting is for cooling, and slotting and drilling are to relieve gass buildup induced brake fade, as DRM said - hardly ever going to happen when wheeling, depending on speed and pad compound, but maybe an issue with the heat generated with pinion brakes.

Drilling to reduce weight - I guess there's no argument that it does reduce weight - but it's my opinion (from the books I've read on the subject) that the primary reason for drilling is not weight reduction but gas release (although the slotting is now generally considered more effective). But I guess there's a lot of different rotors and designs.

Nuttin wrong with looking cool either - 'speciallyif you admit it!

I wouldn't take tech advice from a Pilot either....I'm a Tactical Navigator!!!! :flipoff2: :flipoff2:

Originally posted by Dan Dibble



You have not driven one of these pinion braked rigs!!:rolleyes:


Bill, I will get to you in a minute.

Dan

I could care less about having driven one or not - that doesn;t change physics :rolleyes:

So, since you seem to want to dismiss it out of hand, why would 2 rotors/calipers per pinion not help? More brakes to stop the vehicle seems like a good idea to me, but hey - I guess since I haven't driven a pinion brake vehicle, I am not allowed to toss out ideas...

More brakes to stop the vehicle seems like a good idea to me

sounds like a good idea, yes - but it's completely unnecessary. I will reiterate that one brake can lock up all 4 tires on my rig, pretty easily. More pads may help with heat buildup, but additional braking force is not a reason to add rotors and pads. Eventually I'll get a brake on the front axle, but just for locking the front and pivoting the rear when i get rear-steer, not because I feel like I need more brakes...

Originally posted by elf_cruiser


sounds like a good idea, yes - but it's completely unnecessary. I will reiterate that one brake can lock up all 4 tires on my rig, pretty easily. More pads may help with heat buildup, but additional braking force is not a reason to add rotors and pads. Eventually I'll get a brake on the front axle, but just for locking the front and pivoting the rear when i get rear-steer, not because I feel like I need more brakes...

Completely unnecessary?

Woo-hoo... I can get a drum/drum vehicle to "lock up".... that is not the issue.

The issue being brought up is repeated traffic type stops, etc. And it is my thought that the additional rotors/calipers WOULD be beneficial.
With every stop, you are spreading the braking force over more area, less heat per rotor means less fade, means BETTER BRAKING... Unless you have some reason why this would not be the case?

I tossed out the idea of running dual disc's per axle in THIS THREAD FROM A WHILE BACK (http://www.pirate4x4.com/forum/showthread.php?s=&threadid=97181&highlight=pinion+brakes) and it was pretty much discounted as unnecessary as well. What I keep hearing in these threads is that the pinion braking systems are on/off with little or no modulation, and they do get hot under use. Of course they are going to be touchy, your only running one or two calipers off a MC that was designed for 4 wheel brakes and is still flowing the same ammount of fluid/pressure. Running the dual disc per axle would make the pinion brakes more like a normal brake system in relation to fluid demands, and probably go a long way towards driveability. As to the heat, the dual discs should greatly reduce heat buildup and stop the smoking pad/brake fade.

Is there a reason that no one has tried this yet? Too expensive? Too complicated? Or are people just figuring that one works ok and to hell with trying to tune their systems?

Personally I think the on/off switch that people claim is just a trait of pinion brakes is actually a design flaw that is easily remedied with either MC application or returnign to a brake system that uses the MC to its potential.


I'm just curious about this as I run normal axles and dont think I'll ever run pinion brakes. Good discussions tho, which is what brought me to this board in the first place.

DRM,

Save yer breath man - elf doesn;t really get how to describe or even evaluate "good braking" (no offense man - but DRM's right - being able to lock em up means diddly in brake performance evaluation).

Now, if he/ thay can describe thier swept area per ton, provide pressure and temperature readings (you do know about temp. indicating paint and how to use it to test/evaluate brakes right?), and show the calculations they made to figure their brake torque, well then maybe we can have a meaningful discussion.

Till then, "My rig brakes good" is just way to damn subjective to mean diddly

your only running one or two calipers off a MC that was designed for 4 wheel brakes and is still flowing the same ammount of fluid/pressure. Running the dual disc per axle would make the pinion brakes more like a normal brake system in relation to fluid demands, and probably go a long way towards driveability

Actually, no it wouldn't not at all, not in the way you're thinking.

Operating the single caliper from a MC designed to operate 2 from a single piston (assuming a conventional dual tandem-piston mc) results in half as much force and twice the movement for a given amount of pedal input, pressure in the system remains constant.

The equations are:

F2=(F1*A2)/A1

Where:
F2 = force on piston 2 (caliper piston(s) in pouns
F1 = Force on piston 1 (MC piston) in pounds
A2 = Area of piston 2 in sq inches (caliper piston(s)
A1 = area of piston 1 in sq inches (MC piston)

You can see that the bigger the caliper piston(s) and/or smaller the MC piston the greater the force. Same principal as your floor jack - look at the input piston you jack with the handle - tiny area, and the output piston that pushes the jack arm - MUCH larger - this way tremendous force is generated with very little input force required....the drawback 9as the below equations show) is that large movement is required (you make a big long sweep with the jack handle but the jack head only raises a little bit)

M2=(M1*A1)/A2 where:

M-movement in inches
A= area in sq inches
1 = MC piston
2 = caliper piston(s)

You quickly begin to see why a thorough understanding of the concepts are required in order to design a satisfactory system, and why so many people post complaining about brakes - for some reason people know everything about engines and suspension but not even the basics about brakes
:confused: :confused: :confused:

Uhhh.... maybe increased surface area and braking force?

DRM - your words indicated that you thought dual calipers would add braking force. I was simply stating why additional braking force is not necessary. I'm sure it would help with cooling but who cares?? These are rockcrawling rigs, not F1 cars. The brake properties that Bill mentions are fine and good, but do they really matter at .25 mph over a boulder field?? Once again, if you were to DD your pinion braked rig, it may be benefitial to do some R&D and possibly go to dual rotors/calipers, but as we(those whose use pinion brakes) have agreed, they are best kept on the trails and off the road unless necessary.

BTW -locking up all 4 tires means that i can lock up all 4 tires, nothing subjective about that. I've driven many other 4bys that can't stall their own motor in 4 lo, and autos that drive through the brakes. I don't know, care, or worry about "swept area per ton, provide pressure and temperature readings (you do know about temp. indicating paint and how to use it to test/evaluate brakes right?), and show the calculations they made to figure their brake torque" - I know my rig stops, and that's better than most...

Thanks Bill,

Guess I mistated, instead of over pressure with only one caliper, it should have read over travel. I think it was CJ in one of these threads that said he only had about 1" of pedal travel and that is the point I was aiming at.


I'll agree that most of the people designing these systems dont have a full understanding of the principals involved, myself included. Therefore, why not take the backyard engineering degrees out of the equation. If you use a donor MC designed for 4 wheel disc brakes, and use all 4 calipers, what is there to figure out? I think its when people start indiscriminatly plugging ports and altering fluid volumes that trouble starts. Are the results livable for those running these systems? Guess so since they rave about being able to lock the wheels, but I think there has got to be a better way to end up with a brake system that will not only lock the wheels, but be able to stop to vehicle with little or no drama.

Elf - as I said, the discussion was NOT just talking about off road, or rock crawling, the discussion was also talking about how well pinion brakes "do" and "could" work on the road.

I know severlal people running them off road - and agree, for that purpose they seem to work just fine.

But why not consider other options? Why not talk about ways to make the brakes better, so you COULD feel comfortable about running pinion brakes on the road? That is all I was getting at.

Elf - what DRM said that was what I was getting at too...I agreee - they're prob ok fine for offroad only use - heck, I know guys who have gone wheeling with a granny low manual and no brakes at all.

But it's the on-road bit that scares me ....a lot, especially if you say "can get by" or words to that effect.

Daniels testimony - now there's an experience....and it sounds like all were lucky the outcome wasn't much worse. Daniel - how was the "emergency steering manouver" in that beast? Must have been a little hair rasing too

kwrangln, if I was fiddling with a pinion brake setup - I would prob do quite a bit of experimenting with pedal ratios too.

Originally posted by BillaVista
kwrangln, if I was fiddling with a pinion brake setup - I would prob do quite a bit of experimenting with pedal ratios too.

Yes, this is another reason I contacted Willwood engineering. They helped me pick the master cylinder size and pedal ratio so I would have some "feel".


Dan

ok here is my experience with my pinion brakes. I have had mine on for two months now seeing lots of trail action every weekend and very minimal road use. As for in the woods they work great with no problems.I have not any problems with burning pads, blue rotors, or cooking any seals.I have a 4speed which probably helps with some of this.
In regards to street driving it is a considerable amount different.The truck stops great;but, very ABRUPTLY.That is the part I do not like.As a matter of fact I really try to drive slow on the road if I have to because it scares me it stops so fast.My brakes tend to be very touchy with it mostly being on or off although I am learning how to feather:eek: the brake on the roads. I run one brake in front and one in the rear.The truck has been driven for 15 -20 miles on the road a couple of times at speeds of 5-60 mph between trails with no problems other than the awkward abruptness of the brakes on the road. but, most of the time it only sees speeds of 20-30 mph from my house to the trail head(1 mile from backdoor:D ).
So in my experience mine work great for the woods and trail use.A bit scary on the road at speeds over 30-40 mph because of their abrupt stopping charecteristic. based on this I would not recommend them for a vehicle that sees more road time than trail time. Just my take.

Originally posted by DRM
Uhhh.... maybe increased surface area and braking force? :confused:

We have been trying to tell you that braking force is what we are trying to get rid of. Pay attention. :rolleyes:

Just like Brian said, pinion brakes work too well and the best way to run them is with a manual brake system. You cannot run them with power brakes, that is where you get the "on/off" effect. You want to throw all that engineering stuff in there, but it is really irrelevant. I am running the stock Samurai brake system on mine, with two 4 piston calipers. My little master cylinder was never meant to push fluid to two large 4 piston calipers and it is still way too much braking power.

The only real problem that we have is with heat (and that isn't really a problem unless you ride the brakes down a long hill). That is only because the rotor is turning at 200 mph when yours is turning 30 mph. You slow down from 200 mph and see if you don't have heat problems.

All this bashing is nuts. The bottom line is, pinion brakes work great. What you have to do is rethink the braking system itself. It is hard to adjust your thinking to believe that a manual braking system is preferable over power brakes. I would not recommend them for the DD though, because of numerous drawbacks: overheating could be a problem, you would have to change pinion seals on a regular basis and you would not have the brake feel that you are used to with wheeled braking systems.

You want to throw all that engineering stuff in there, but it is really irrelevant.
Dude, that's hillarious. NO IT IS NOT...your post is FULL of technical errors, if people read it, and believe what you say (because you have a badass rig or street (trail?) credability or whatever) they are going to be dissapointed.

I'm not dissing you - just trying to help out with some facts.

it is still way too much braking power

First - define what you mean by "braking power"....does it take into account speed, number of applications, etc. Most likely you just mean you can step on thebrake and come to an abrupt stop, at least once. Whoop de doo...that doesn;t make good brakes imho.

That is only because the rotor is turning at 200 mph when yours is turning 30 mph. You slow down from 200 mph and see if you don't have heat problems.

No, this is wrong. The reason;s been posted before, prob in this thread, I've said it myself a few times. I'm not going to repeat it all. It has to do with thermal absorption.....damn, there's that annoying stupid irrelevant engineering crap again!

The bottom line is, pinion brakes work great

Define "work great"......

Look - I'm not trying to embarass you, or piss you off, but dude:

ENGINEERING CRAP does matter....ESPECIALLY with brakes!!!!!

Originally posted by BillaVista

Dude, that's hillarious. NO IT IS NOT...your post is FULL of technical errors, if people read it, and believe what you say (because you have a badass rig or street (trail?) credability or whatever) they are going to be dissapointed.

I'm not dissing you - just trying to help out with some facts.



My post is not full of technical errors. How can you say that when I am speaking from experience and you are speaking from behind a keyboard somewhere. I understand that you have done a lot for the board and have helped a lot of people out with your technical advice and write ups, and I appreciate it as much as anyone else, but what did I say that would disappoint anyone?

I have seen pinion brakes using calipers from huge Wilwood 4 piston calipers, all the way down to small, single piston calipers that looked like they came off of the rear end of a motorcycle. And they all stopped the vehicle like a damn Ferrari.



Originally posted by BillaVista

First - define what you mean by "braking power"....does it take into account speed, number of applications, etc. Most likely you just mean you can step on thebrake and come to an abrupt stop, at least once. Whoop de doo...that doesn;t make good brakes imho.



You need to keep in mind, I am talking about a trail vehicle. I already said that they are probably not recommended for street use. I can use my brakes as often and as hard as I need to.

Just like Elf was saying, a lot of rigs out there can't even use their brakes for various reasons. I have seen all too many rigs that suffer from lousy brakes, as everyone has. They either have to mash them to the floor with both feet to hold them on a hill or they won't even work when in low range because the gearing overruns the brake system, etc. That kind of thing will never happen with pinion brakes. You just put the weight of your foot on them and you are not moving, period.

Originally posted by BillaVista

No, this is wrong. The reason;s been posted before, prob in this thread, I've said it myself a few times. I'm not going to repeat it all. It has to do with thermal absorption.....damn, there's that annoying stupid irrelevant engineering crap again!

Define "work great"......

Look - I'm not trying to embarass you, or piss you off, but dude:

ENGINEERING CRAP does matter....ESPECIALLY with brakes!!!!!

Whatever. If you try to slow two vehicles down from the same speed and the rotor on one is turning 7 times faster than the other, it is going to get hotter, that's friction. The thermal absorption is going to be the same for a given rotor regardless of what speed it is spinning, so until they come out with a rotor that is designed to spin 7 times faster than normal, we will just have to deal with the heat.

You're not going to embarrass or piss me off. All I am trying to do is keep the guys that are putting rockwells in their rigs right now, from being intimidated by all this technical jargon from people with no experience with what the are trying to bash. If you want to make constructive criticism, go find some guys that are running pinion brakes and drive their rigs, then come back and critique.

Next time, please don't add adjectives to my post. I never said engineering stuff was stupid, annoying or crap.

OK, maybe FULL of errors was an overstatement on my part, and I do appreciate that what you're saying is that it works og (or great, Igues depending on perspective) for a trail vehicle - fine, no argument there. And yes, I freely admit I have no hand-on experience with them.

BUT - this is a tech discussion, and not just a relating of experience or opinion (remember - what you think of "stopped the vehicle like a damn Ferrari" and mine might be quite different), and I do know the lwas of physics that govern this, and I do have lots of practical experience with plenty of other brake systems (not from just behind a keyboard), and the physics are the same REGARDLESS of the system - I guess that's my MAIN point.

See - what if someoen reads your post and uses it to "infer" or "extrapolate" the information to something else? It's pretty unlikely anyone reading it is doing so just to exactly copy your rig and setup and driving style - and even if they did they might have different expectations of "great brakes" - so we have to assume that some of this might happen. And that's all I want to clarify - the facts or physics so that people don't infer something not in evidence. For example - I can't touch your practical experience - but I can guarantee, that if someoen read it, the built a rig with a tiny single piston single pinion brake and went and drove it down a twisty mountain road, expexting it to "stopped the vehicle like a damn Ferrari" thay would be in serious trouble. I'm suggesting you said that - you made it clear that you were talking trail only. But I'm just adding to the picture for those reading and contemplating other variations.

So - If you try to slow two vehicles down from the same speed and the rotor on one is turning 7 times faster than the other, it is going to get hotter, that's friction

This is fundamentaly wrong. Speed of the rotor has little, if anything, to do with how potentially hot the rotor gets. (It does have an effect on swept area per weight unit for one wheel revolution which is the answer to one of my above questions and the truth behind the "gearing effect" people talk about). What determines how hot the rotor gets is simply the kinetic energy of the vehicle - and the conversion of that energy into heat (and some noise) is exactly what all brakes do and how they work. By using friction between pad and rotor to convert the total kinetic energy of the rig ino heat that the rotors.drums must absorb and dissipate. And the weakness of the pinion brakes is that because they have only single, usually small rotors, they have a MUCH smaller capacity to safely absorb the heat for any given kinetic energy level (speed if you like) without warping, producing enormous brake fade, or turning to molten mush.

'das all I'm saying.

I'm not trying to "bash" anything - just provide info.

please don't add adjectives to my post. I never said engineering stuff was stupid, annoying or crap.

OK - my bad - sorry, won't happen again. I won't if you don't (I never "bashed") ;)

350 Sami - stop a second and THINK.

I haven;t seen anyone here say they are not "ok" for trail use.

But you seem to be fighing this dicussion for some strange reason...

Why can we not discuss and explore HOW TO MAKE THEM BETTER?

I mean really - stop taking this like a personal attack. You have experience with them, but all you have managed to contribute to this point is "they stop fine". Wow. How in depth :p


So how about instead, you step up to the plate and further the discussion. Maybe after some thinking, and working, a system could be worked out that would be BETTER - making them a viable option for on road use as well.... what do you say? :)

Originally posted by BillaVista
And the weakness of the pinion brakes is that because they have only single, usually small rotors, they have a MUCH smaller capacity to safely absorb the heat for any given kinetic energy level (speed if you like) without warping, producing enormous brake fade, or turning to molten mush.

This is exactly my line of thinking for a second rotor per pinion!



Then we are talking 4 rotors per vehicle, 4 calipers... sure sounds more like a regular braking system to me ;)

I keep thinking that the added rotor/caliper is what is gonna make repeated road stops possible by spreading out the braking force to reduce all that technical stuff Bill mentioned as being problematic :p

Yeah DRM, lots of people have suggested that in the past, and if you had to DD your rig in traffic or on the highway alot, it would be a great idea. BUT - I have an easier solution! All you have to do is lock em up every time you want to stop! Let the tires be the point of friction!! No brake fade! No heat buildup!! What a prrrrfect solution!!!



seriously, though - USA6x6 has had wheel brakes available for a while in several variations for rockwells, so if you really want to DD your rockwell shod rig, just pony up the extra bling and get wheel brakes. Notice how Jeeper111 hasn't even replied to this thread, that's because he(for some dipshit reason) wants to DD his jeep, or at least be able to, and so he got the first set of rockwell wheel disc brakes from USA6x6.

I won't argue that pinions brakes work on the trail... I've seen it. Running just one, though? I'd blackflag that at vehicle inspection. No parking brake, no redundancy... no thankyou.

...so until they come out with a rotor that is designed to spin 7 times faster than normal...
Now THERE is an interesting discussion! How would that be modified? Larger rotors --- well, that cuts both ways. A larger radius would only increase the relative rotor/pad speed. Thickening the rotor would increase thermal mass and help with fade-resistance.

Slotting and drilling could help, too, but insufficient heat-soaking capability may be the bigger problem (I'm thinking of Daniel's anecdotal evidence of brake fade/failure during a 60-30 mph maneuver). Cooling tricks can make over-heating less likely, but increased thermal mass might just eliminate the problem entirely. A combination of fixes may be required (the disk needs the capacity to absorb a bunch of heat and then radiate it quickly) ... perhaps venting a thicker rotor might work well.

Perhaps two small-radius rotors per pinion? This would have the additional benefit of putting more volume into the caliper end of the system, perhaps minimizing the on/off-switch behavior that some folks have described. One big drawback would be having to agree with DRM. :flipoff2: :p

Randii

Originally posted by Aceguy
I would never use a pinion brake setup on the highway for the simple reason that there is no mechanical ebrake. I would want at least one braking system at the last possible point of failure-the wheel. However, my rig is trail-only, so I feel that pinion brakes, coupled with a t-case e-brake will be more than satisfactory.
Rovers use a tcase ebrake for the rear shaft. I use it constantly on big decents, as I have an automatic and shiaty engine braking. It is a 14" drum and the only downside is that used as a pinion brake, is that coupled with my detroit, there is a slight amount of play.

Skipping over the many pages of discussion to address your question: what if the other stuff does NOT hold. Buddy of mine locked his up, stood it up on the front tires, & promptly broke a front axle. Having an open frontend, he essentially had no brakes until the rear touched back down. Here's the vehicle in question:

http://www.gumbo4x4.com/Gumbo820.JPG

TEX

If you use a donor MC designed for 4 wheel disc brakes, and use all 4 calipers, what is there to figure out? I think its when people start indiscriminatly plugging ports and altering fluid volumes that trouble starts. Are the results livable for those running these systems? Guess so since they rave about being able to lock the wheels, but I think there has got to be a better way to end up with a brake system that will not only lock the wheels, but be able to stop to vehicle with little or no drama.


What if you used an adjustable proportioning valve? I know this is the proper method of converting a disc/drum vehicle to disc/disc, and the pro. valve made a big difference on my pedal pressure when adjusted properly.

but who remember ttc, the frog won the braking test with a single pinion brake. the stopping power is incredible, but it does come with a heat build up that can lead to brake fade. i would never recomend it for a full time street rig, but i drive mine to trail heads and never worry. this is jmo. mike

While pinion brakes might be good enough for the trail, I saw a very good reasion not to trust them on a DD. Simply I had to stop today and help a guy pick up the drive shaft of his Toyota truck from the middle of the road. Now where would he have been if the brake had been mounted on that shaft? There is a very good reason you will always see a disk/drum attached solidly to each wheel...........

mine is on the back side of the rear axle, if the drive shaft fell off it would not matter, it would stop

Originally posted by WindRider
While pinion brakes might be good enough for the trail, I saw a very good reasion not to trust them on a DD. Simply I had to stop today and help a guy pick up the drive shaft of his Toyota truck from the middle of the road. Now where would he have been if the brake had been mounted on that shaft? There is a very good reason you will always see a disk/drum attached solidly to each wheel...........

Most pinion brakes are mounted to the opposite flange from the driveshaft on rockwells, a driveshaft has nothing to do with braking with pinion brakes unless they are only running one.

Lazarus, Arise and Walk!

I saw CJ_Lagos note this in another thread: http://www.pirate4x4.com/forum/showthread.php?t=297088
"My pinion brakes were never that great on the road, in fact I downshift as much as possible and avoid using them...but off-road is where they shine and are the :BOMB:

...and decided to resurrect this gem. :p

We probably won't get much feedback from Daniel, but waddabout the rest of yas? Are ya all still kumbayah-ing away to the pinion-brakes-are-cool-for-the-street tune?

Randii

Lazarus, Arise and Walk!

I saw CJ_Lagos note this in another thread: http://www.pirate4x4.com/forum/showthread.php?t=297088
"My pinion brakes were never that great on the road, in fact I downshift as much as possible and avoid using them...but off-road is where they shine and are the :BOMB:

...and decided to resurrect this gem. :p

We probably won't get much feedback from Daniel, but waddabout the rest of yas? Are ya all still kumbayah-ing away to the pinion-brakes-are-cool-for-the-street tune?

Randii

You don't quit do you? I routinely drive my rig on the street to and from trailheads, up and down trail 1 in tellico, I lead hundreds of paid customer vehicles on paved roads to the trails at Camp Jeep, and I drive on major roads at high speeds when I'm on my way to somewhere like Paragon(can't camp too close). While wheel brakes would certainly be a better choice for the road, you can't argue that the pinion brakes work. We understand, and no one will argue, that they don't belong on a daily driver by any means. But for an all-out trail rig, they're hard to beat. This is :usa:, we can do what we want without your permsion or approval. WE GET YOUR POINT!

EDIT: Can you honestly say you've owned a rig with pinion brakes, or even driven one?

You don't need my permission... and you probably won't get my approval. But it's nice to know that you care. :p :flipoff2: :p

I do wonder if more people, after actually using their pinion brakes for a while, are planning what Dibble plans. He's got arguably the best-designed, best-implemented set of pinion brakes out there, and he's planning to pull them and install wheel brakes. :idea:

Kumbayah, kumbayah. :flipoff2:

Randii

EDIT: Can you honestly say you've owned a rig with pinion brakes, or even driven one?
Have not owned a pinion-brake (worked with a few driveline brakes over the years) rig, but have driven a couple, and have followed directly behind a couple in the Sierra and around Moab.

One of the nice things about the smell of burnt friction material is you can smell 'em coming on the streets and get outta the way! :flipoff2:

Randii

I do wonder if more people, after actually using their pinion brakes for a while, are planning what Dibble plans. He's got arguably the best-designed, best-implemented set of pinion brakes out there, and he's planning to pull them and install wheel brakes. :idea:


Dibble has got two huge flaws with his setup: rear detroit and from what I've heard from Station the automatic has some problems. I'm sure Dan can tell us more, and we'll value his opinion a lot more than yours :flipoff2:

Oh...and I call BS that you've driven with them like you say :D

Oh...and I call BS that you've driven with them like you say :D
Whatever :shaking: ...I have no pictures handy of myself in pinion-braked buggies, I'm generally *behind* the camera... but if you want to play 'prove-it' you might as well go join the politico's in chit-chat. :rolleyes: There's no winning these e-battled claims of BS, in most cases.

I'm still interested in talking to folks who've streeted pinion brakes, and whether they choose to repeat it. You're already on record as continuing to street-drive a rig "with pinion brakes that were never that great on the road..."

Human nature is to defend what one runs... I think we all fall victim to self-justification, in one way or another. Knowing this, I pay even closer attention to people who realistically cite flaws with the setup that they have. :cool2:

Randii

Dibble has got two huge flaws with his setup: rear detroit and from what I've heard from Station the automatic has some problems. :D


Biggest problem here is Station. :flipoff2: Yes I have a rear locker and it does help with steering just like a front locker helps with steering. (keeps the wheels from pushing). Now is this worth the driveline slop?? I dont know. I do know I dont have any plans to pull that diff apart again for a long time. :p

Ok now about the auto, I walked into TCI and talked with them about how my trans was to be built, Full comp (kevlar, sprags, shafts) reverse valve body, COMPRESSION BRAKING 1,2,3 GEAR. Well somehow I ended up with only comprssion braking in third. I called them and they are not shure how it happened but promised to freshen it up and fix the braking issue next time I had it out. (This has Nothing to do with the pinion brakes) other than mayby I wouldnt use them so much if the engine braking worked better.

Back to Station, he would rather stayhome and work on his shit. and I understand this but damn two years is a long time. My motor has to be pulled to pull the trans. Not going to happen without some real failure or durring the motor swap NEXT winter. ;)

Ok, back to the discussion, I have driven on the road over sixty miles in a day before with out a single problem, 50mph for over twenty min at a time.


Two things to remeber here

1. Our rigs are NOT cars. Think of them as equipment. (forklift, backHOE,ect)

2. Pinion brakes will never be wheel brakes.

As I have said before, anyone that is at a event where we are COME GET MY RIG and drive it, seriously. I like to hear the comments.

Dan

I did not like my pinion brake at first, but after I got the flow regulated through a one-off custom proportioning valve, my brakes no longer "clunk" or "stick" like it used to.

Now, with discs on the front and the pinion brake in the rear the only time the pinon brake overrides the fronts is in a total panic situation.

Mine does not heat up.....Wildwood caliper and vented brake rotor.....

When it is in 4WD, the pinion brake takes over and will peg you to the steering wheel it works so well.

I'm still interested in talking to folks who've streeted pinion brakes, and whether they choose to repeat it. You're already on record as continuing to street-drive a rig "with pinion brakes that were never that great on the road..."

Human nature is to defend what one runs... I think we all fall victim to self-justification, in one way or another. Knowing this, I pay even closer attention to people who realistically cite flaws with the setup that they have. :cool2:

Randii

Good answer :cool2:...but why you continue to harp on this particular aspect of these setups is beyond me(especially with virtually no first hand experience). No one is arguing that pinion brakes perform just as good as wheel brakes on the street, and everyone agrees pinion brakes work better off-road than wheel brakes do, IT'S CALLED A TRADE OFF! Have you bothered to consider these streetability concerns with the rest of the components these rigs run? Let's be honest, 44" Swampers at low pressures, full hydraulic steering, soft long-travel suspensions, potential play in rear steer setups with single ended rams, custom scratch built vehicles(potential for mechanical failure is much higher than with a production design), etc, the list goes on and on. What you don't seem to grasp is that they can and do work on the road, maybe not perfect but they work. We're talking about hardcore no-compromise trail rigs that only get driven on the street to and from trails, not your average lift-kit'd YJ with 33's that doubles as a daily driver. Please give us some credit!

Biggest problem here is Station. :flipoff2: Yes I have a rear locker and it does help with steering just like a front locker helps with steering. (keeps the wheels from pushing). Now is this worth the driveline slop?? I dont know. I do know I dont have any plans to pull that diff apart again for a long time. :p

Slop is one thing but locking/unlocking while braking is another. I had a lot of time behind the wheel in my Jeep with two detroits and after welding the rear there was a huge improvement in how well the pinion brakes work. I wouldn't be wasting your time if I hadn't "been there/done that" and I honestly think it will be well worth your time to take the axle apart. It was kinda funny how I fell into welding the rear. My friend eddie needed a detroit for his project and and I was short on cash at the time, I figured what the hell, so I pulled my rear detroit and sold it to him. I welded the rear back up and didn't drive it for a while but the next time I did I was AMAZED at how much better the brakes worked...TRUST ME! Oh, and who cares about the diff unlocking for turning, you've got rear steer!

Yeah...fawking Station :flipoff2:

One of my friends uses 4 wheel disks on his Rockwells plus pinion brakes front and rear for E-Brakes and 3 park locks for digs and such...Over kill? over budget? yes! But hay, he is nuts behind the wheel and needs brakes more than money!

Pinion brakes work on the street sure...are they safe? well maybe, unless you break an axle on an open diff you will have brakes, are they enough to emergency stop you from 100MPH? Probably, but not on a regular basis (IMHO)

The rotor is mounted on the pinion not the drive shaft so U joint failure won't matter but it is turning 6.72 x faster than the wheels so it will wear a lot faster. It is like if you are running 10 mph the brakes think that you are running 67.2 mph and your truck is 6.72 x lighter. so if you are on the street from time to time they should be fine. If you run 100 mph and have to stop fast? Hello heat! But it should dissapate fast as the rotor spins fast.

Can you run Pinion brakes plus a trans brake for an E brake? sure, and it is a good Idea unless you brake a U joint, then I hope you have a park lock for each axle!

people have been using pinion brakes for a long time without too much trouble
and they do work on the street but there is a point where I would prefer a disk at each wheel.

FINALLY! we can settle this 3yr old debate.

:rolleyes: