I need more stopping power!this is what I was told might help-please look it over and tell me what you think:
ok my jeep has dana 44 scout axles with the scout calipers (front and rear disc brakes-all scout front end parts) and jeep power brakes and s.swamper 35x15.5 tires.
I was told to remove the valves coming out of the master cylender for better fluid flow use the largest brake lines (diameter)from the auto parts store and use an adjustable prop. valve.will this give me better braking power?Im sick of double pumpin!
Ive already removed one of the valves(large bowl going to the front brakes)and Im going to get the other parts in a while.Any input on this would be great.I dont want to be doing all this work if its not going to help.todd

ps;Ive always wondered why the line (brakes)come rolled up by the master cylender.what is the reason for this?

http://www3.sympatico.ca/1crazy-jeeper/todd.html

todd---your spinning your wheels if you think larger diameter brake lines will make even the slightest difference.....the only answer is a larger master cylinder.

Todd- Get a clue:rolleyes:

That sh!t won't help one bit, but go ahead brother if you feel like wastin' your time and then coming back here and posting about how you tried "a bunch of crap" and it didn''t help.

I've got an easy fix that'll probably cure your problems and cost about $20 total. It stops my Jeep perfectly and you can check the specs in my sig to see what I'm running.

In fact I'd love to help you, but you were to stupid of a newbie to even tell us what kind of "Jeep" you had, and I'm not wasting my time to search your webpage and find out. Maybe I'll let you know if you reply to this promptly, since I'm on lunch now and feeling good:p

stupid newbie, POST ALL PERTINENT INFO TO THE QUESTION Don't expect us to search it out so we can help YOU!

ok Ill take that!I just recently signed on and didnt know my sig want in there.dumb ass!:smokin:

gimme the $20 fix!

Todd Kelch
1980 CJ-7,
Amc 360,T-18a,Dana 20
Front& Rear Dana 44's(4.27gears)
Spring Over + 2.5" Bodylift,
35"x15x15.5 S.Swampers-sx,
6 Point Rollcage,Rancho RS9000's,
& Warn HS9500 Winch!
(ect.........................)
And of course "TREMCLAD YELLOW

You didn't mention if your Jeep had power or manual brakes from the factory, big difference. Manual brakes may make it next to impossible to stop no matter what you try.

My solution will work with power brakes, and should also help w/ manual. Just get a master cylinder from a '86 (or any mid eighties I guess) Ford E350 (1-ton) van. These suckers move 1.5 times the fluid of a stock YJ master (I'm sure that similar to a CJ) The master cylinder will be $15 at autozone (rebuilt) with core ($5 at a pick n' pull). There's the $20. Now I got my core for free and spent $3.00 on new lines to go from the master cylinder to proportioning valve because the fittings were different from stock. My total was $18. You can also disable the proportioning valve to send more fluid to your rear discs. Search here for the directions on how to do this, it's been posted quite a few times and will cost you nothing. You'll need to wobble the holes and perhaps touch grind a little to fit this master cylinder on the stock mounting studs (assuming you mount to a 2-stud vacuum booster). If it's manual I'm not sure, but I bet you could get a larger master for manual brakes also.

Change the master cylinder first. Then if it's not enough and you have a vacuum boster, change it. If your brakes are manual, convert to power :D ;)

sounds like Ive got a weekend project coming on.todd
ps this is where i could be an a$$ and tell you I put the power brakes thing in the 3rd line of the first question.(but i wont)just kiddin todd-thanks bigdude!

My bad.:flipoff2:

The easiest thing to do will be drill the holes out to 9/16" if they don't fit the studs well. I tried that wobbling bullsh!t and finally just drilled them out. Still plenty of meat. Like I said I just had to touch grind to get the master to seat properly. I also got lucky and didn't have to adjust the push-rod length, if you've got a jeep or ford booster you shouldn't have to adjust the push-rod either (minimal if at all). Take your old lines that go from the master cylinder to the proportioning valve and you should be able to get the conversion lines (different fittings on each end) from your new master cylinder to you old proportioning valve. I got mine from "discount auto parts".

one more quick question-when I go to the pick and pull-did the e350 van come with power and manual masters?which one to pick?

Originally posted by todd kelch
one more quick question-when I go to the pick and pull-did the e350 van come with power and manual masters?which one to pick?

Every one I've seen has power brakes. The new one is only $35 if you don't want to screw with a junkyard. They also look just like a Jeep master cylinder so I don't think they'll know the difference at the auto parts store. The only difference is that the piston is 1/8" larger in diameter and 1/8" longer stroke. That makes the ~45% volume increase. You could just supply something similar looking as a core.

Get the one for power brakes (the one with the booster). The junkyard is only 5 minutes from my house and I knew the van was there, plus I'd get the master for free. It was so easy I couldn't pass it up. Otherwise I would've just bought a new one and been done.

Hydraulics work on leverage based on ratio of diameters of pistons. A larger master cylinder piston diameter will decrease the pressure generated in the system and reduce braking power. The larger volume of a longer stroke cyinder may help if that was a problem.

Tri-county gear sells an adjustable link so that you can redrill the braket and increase the leverage on the bellcrank. Also, a GM dual diaphragm booster will greatly increase the power assist.

Originally posted by Tmartin
Hydraulics work on leverage based on ratio of diameters of pistons. A larger master cylinder piston diameter will decrease the pressure generated in the system and reduce braking power. The larger volume of a longer stroke cyinder may help if that was a problem.


I'm sure you've tried this modification before right:rolleyes: If you haven't done it then how could you sit here and say it'll decrease the pressure enough to detract from the performance:rolleyes: You don't know what the f@ck you're talking about newbie. Theoretically what you said holds true, but in real world application can the difference be felt, or does it detract from performance? Or is it possible that the vacuum booster provides a quick enough pedal/push that any possible decrease is negated? You obviously can't answer that, because you haven't done it, so STFU.

You also for got to say that if the stroke of the push-rod is not long enough to utilize the available stroke length then there will be no added benefit due to it. BUT that doesn't matter either because you don't know :flipoff2:

Theories about performance are one thing, but real application is another. Do your research before you spout off about how a larger diameter/stroke master cylinder will decrease braking power:rolleyes: That means that after swapping in 1-ton axles with 1-ton brakes on my YJ w/ a larger master cylinder, I now have worse brakes than before. That's why I can lock up 38's at all 4 corners (drums in the rear) at 40mph and with the smaller diameter master cylinder I could barely hold it at idle. You dumbass:flipoff2: :flipoff2: :flipoff2: Thanks for the laugh with your practical knowledge:rolleyes:

Originally posted by Tmartin
A larger master cylinder piston diameter will decrease the pressure generated in the system and reduce braking power

Dude, you're an idiot. This is patently false. The opposite is true. The main thing preventing the brakes from working correctly is the fact that they aren't moving enough fluid, not because the amount of pressure being generated is too little.

Think about it-- the amount of fluid being moved by the larger bore cylinder will move the smaller slave further, per the distance the pedal travels.


:rolleyes:
Jake


Hey Bigdude, did your stock Jeep booster diaphragm bolt right up to the E350 MC? I've been meaning to do this type of swap in my own YJ...

Thanks,
Jake

Originally posted by Jakesteramalamajama

Hey Bigdude, did your stock Jeep booster diaphragm bolt right up to the E350 MC? I've been meaning to do this type of swap in my own YJ...

Thanks,
Jake

F@ck Yeah! It was about the sweetest thing I stumbled onto during my build-up. All I did was drill out the MC holes with a 9/16" bit, clearance the sides a little with an angle grinder (so it would seat fully in the Booster indent), and tighten her up. The push-rod is the exact same length so no adjustment is needed there. Took about 15 minutes to swap once I had the conversion lines and MC in the garage with the old stuff removed. I'm very happy, best brakes I've ever had (and I used to have 4 wheel discs, now I have rear drums that lock up like a mofo:D )

Bigdude or anyone. For us CJ guys, do you know if a CJ booster will fit on the E350 m/c? Thanks for the info, I am doing the brakes on Jeep right now.

Originally posted by cj7jeep
Bigdude or anyone. For us CJ guys, do you know if a CJ booster will fit on the E350 m/c? Thanks for the info, I am doing the brakes on Jeep right now.

I thought the hot swap for CJs was some late '70s Corvette master cylinder (for 4-wheel discs) and that it was almost a bolt-up... you might try searching for that.

HTH,
Jake

yup-its a 68 4 wheel disc corvette mc-but you can guess the price will be jacked up cause it says corvette on the box!I gotta slow down on my jeep spending.....................................what am I saying?!

http://www3.sympatico.ca/1crazy-jeeper/todd.html

Originally posted by cj7jeep
Bigdude or anyone. For us CJ guys, do you know if a CJ booster will fit on the E350 m/c? Thanks for the info, I am doing the brakes on Jeep right now.

Just buy it and take it back if you can't fit it. The holes were wider than a YJ MC stud distance so I drilled them out, clearanced the edges, and the recessed area (don't know what to call it) was a perfect fit.

It's that same MC design as most any. Large metal reservoir that's attached, blah, blah, blah. I think it's a standard design and the only thing that differs is the bore/stroke, fitting size, and stud distance depending on which manufaturer used it. If a CJ master looks the same then I bet it'll work, just try it and you can be the guru:D

I looked at 'Vette masters originally but they wanted over $100 w/o a core for a remanufactured one. The bore/stroke of the E350 is the same as a vette or just slightly different (I've checked before but can't remember). Either way the $15 master was music to my ears and it moves plent of fluid for 1-ton brakes (including my HUGE Dual piston front calipers) so I'm sure it'll lock up everything. In fact if it doesn't I'll send you a crisp one dollar bill:emb:

Thanks Bigdude, you da man :beer:

You could always convert to hydro-boost if you want REAL braking power! I did this on my CJ and just a touch of the pedal will send you lurching forward towards the windshield if you're not careful. I'm running 38's too.

I did mine for $100 but I got a deal from this board from someone getting rid of a setup. I see the units all the time at Pick and Pull in the 70's Caddies.

Just another option for ya.

Originally posted by Kendo
You could always convert to hydro-boost if you want REAL braking power! I did this on my CJ and just a touch of the pedal will send you lurching forward towards the windshield if you're not careful. I'm running 38's too.

I did mine for $100 but I got a deal from this board from someone getting rid of a setup. I see the units all the time at Pick and Pull in the 70's Caddies.

Just another option for ya.

Sounds like you got lucky. most people I know who did hydro-boost had a hell of a time getting it to work and piecing it together. Definitely cost them over $100 and quite a few hours by the time they were finished. I will agree though, their brakes are so strong it's almost scary. Still for about $20 and abotu 20 minutes I don't think this upgrade can be beat if you're lazy:D :beer:

You guys are smoking crack about the prices of a Corvette MC. They are less than $25 for a reman.

Originally posted by Eric
You guys are smoking crack about the prices of a Corvette MC. They are less than $25 for a reman.

I got an early 80's 'Vette master and it came w/o a plastic reservoir- $117, promptly told the guy I didn't want it and he could send it back. Then he told me that w/ a reservoir it was $200+. That's when I decided to discover my other options. Still, $15 is cheaper than $25 for the frugal minded wheeler:D

I spent a lot of time looking through the master cylinders at my part time(autozone). I found that most of the truck MC had piston diameters that looked too large to fit into the recess in my 79 cj5 power booster. My stock cj5 MC piston was ~1", most of the others were at least 2" diameter.

The one I did find that fit with zero modifications was from a mid eighties chevy suburban with JD7 brakes. The piston is slightly larger (~1 and 1/4" diameter) it bolted up with no grinding and no pushrod adjustments. The only difference was the reservoirs were switched (front to back), far as I know it made no difference at all (as long as you switch your lines accordingly).

The line adapters from the stock MC fit directly into the suburban MC. I can lock 33" armstrong mudders with no problem at all. Now I can sound like an 18wheeler when I jam on the brakes.

'86 Chevrolet Suburban with (rpo code) JD7 brakes.
Re-man was like $20 + $12 core.

If I remember I can post autozone part# when I get home.

So if you are buying new m/c and booster can you go ahead and get the correct booster, from the same application? Are the Ford/Vetts boosters too big to fit, hit steering or something. I have an old m/c and booster that are shot, but will use for core charge.

Originally posted by cj7jeep
So if you are buying new m/c and booster can you go ahead and get the correct booster, from the same application? Are the Ford/Vetts boosters too big to fit, hit steering or something. I have an old m/c and booster that are shot, but will use for core charge.

You can get into some sh!t with mounting/space/brake-light switches etc. The E350 booster sticks out about twice as far as a YJ. That was just something I didn't want to get into, on top of that the stock YJ booster works well. You can get anything to work, just will the benefit outweigh the work? It's different for everybody.

Originally posted by bigdude


I got an early 80's 'Vette master and it came w/o a plastic reservoir- $117, promptly told the guy I didn't want it and he could send it back. Then he told me that w/ a reservoir it was $200+. That's when I decided to discover my other options. Still, $15 is cheaper than $25 for the frugal minded wheeler:D

Ahhh, big difference between 68 and 80. I would have done the same thing as you. Cheaper is alwasy better. :D

Yaaaaawwwwnnnnn. A little sensitive Bigdud? You're proof that the empty vessel makes the most noise. My practical experience with exactly the same setup as he asked about in his first post (Scout Dana 44's and power brakes, sorry you didn't catch either of those details in his post the first time. Maybe the written word is a little too abstract and theoretical for you.) is that an upgrade to the vacuum booster alone gave me all the stopping power I needed. I too can lock em up with ease. He doesn't have the same axles as you. Of course one ton axles need a one ton master cylinder. In fact he probably does need to replace his master cylinder as he talks about pumping the brakes. Your practical experience may be great, but your bullshit about the "quick enough pedal push" shows a complete lack of understanding. Scout Dana 44's with rear drums properly adjusted don't need any more volume than the stock master cylinder generates. I agree you need to match a larger master cylinder to significantly larger calipers and wheel cylinders if you run out of travel. Is that what you assumed? If he's pumping his brakes, he's probably got air in the system, a faulty seal in the master cylinder, or possibly f'k up the operation of the system by removing the check valve so that the clearances open up every time he let's off the pedal. If you need to feel validated by having others emulate you whether it's the right solution or not, feel free to, that's what this board is famous for.

I'm glad that an upgrade of your vacuum booster helped you. An upgrade of the master cylinder helped myself and countless others (with 30s and 44's also- not just 1-tons). In actuality every situation is different and a vacuum booster upgrade can accomplish similar results to a master cylinder swap, it's six one way and half dozen the other- but which is easier.

In retrospect my point of "a quick enough pedal/push" did not explain very well the mechanics I was trying to get across so I conceed that it does make me sound uneducated. I know what I meant but could not phrase it properly in "quick" and "easy to explain" terms, oh well:flipoff2: . Jake relayed it in simple tech shortly after myself and I default to his better use of all the correct terms. Argue with him also if you feel he's wrong too :D

From my experience with dana 44 calipers (and some of my friends also) it has been beneficial to upgrade to a master cylinder that moves more fluid. I relayed this and told of my personal experience with the solution (although related to 1-tons in my case). We haven't really delved into swapping larger vacuum boosters because it wasn't necessary after the master swaps. In all actuality it's easier to just swap in a master cylinder and see if it solves the problem, then explore other options if it doesn't. Either way we've both solved our problems so I'm glad you feel like you have a better suggestion than me, pat yourself on the back. If you feel that swapping a larger master cylinder is not a good solution to soft brakes after an axle swap or large tire addition, then I think you'll be finding a few (besides myself and friends) who disagree with you. You also forgot that I earlier stated "Change the master cylinder first. Then if it's not enough and you have a vacuum boster, change it." Huh, guess I covered what your fix also. I just mentioned the easier of the two first and expanded into detail because I've done it myself, whoops.

"If you need to feel validated by having others emulate you whether it's the right solution or not, feel free to, that's what this board is famous for."--- I see no harm in suggesting a cheap fix that can be easily reversed if not successful. His money can also be refunded for the parts return so nothhing would be lost. What do you think I'm the only guy whos ever swapped a master cylinder to improve braking, then recommended it to someone else:confused:

You also mention scout dana 44 rear drums in your reply. Well he clearly sates in his original post that his vehicle is equipped with scout calipers all around for his front and rear disc brakes. So...sorry you didn't catch either of those details in his post the first time. Maybe the written word is a little too abstract and theoretical for you. :flipoff2: :flipoff2: :flipoff2: (nice attempt at a smack though:rolleyes:, then contradict yourself, you dumbass)

I too have the Dana 44 spongy brake blues. I've swapped in a new M/C after properly bench bleeding it, bled the brakes correctly, re-adjusted them, taken it to a brake shop to be bled, blah, blah, blah. It's still a hairy ride when some jackass jumps in the carpool lane in front of you. It's simply a matter of the M/C not pushing enough fluid. Before I go through the headache of swapping an entire booster, I'll spend a couple hours and try the E350 M/C.

Originally posted by withamc
I too have the Dana 44 spongy brake blues. I've swapped in a new M/C after properly bench bleeding it, bled the brakes correctly, re-adjusted them, taken it to a brake shop to be bled, blah, blah, blah. It's still a hairy ride when some jackass jumps in the carpool lane in front of you. It's simply a matter of the M/C not pushing enough fluid. Before I go through the headache of swapping an entire booster, I'll spend a couple hours and try the E350 M/C.

Thank you:beer: At least somebody sees my point. It's so much easier to try a master cylinder swap first (on top of being pretty cheap) vs. changing out a booster:p

Originally posted by bigdude
Jake relayed it in simple tech shortly after myself and I default to his better use of all the correct terms. Argue with him also if you feel he's wrong too :D

Hey guys, :flipoff2: I said my peace. Leave me outta this...

Finally got around to swapping in the E350 M/C. For all you doubters out there - WHAT A DIFFERENCE! No more pedal to the floor crap. I still need to look up the prop valve trick, 'cause the rear brakes still don't lock on pavement, but this is way more than adequate, and a big improvement. Thanks for the info bigdude.

Dam good chunk of advice Bigdude, I was looking at upgrading the brake booster on my 89 XJ and have heard mixed results about it. I just picked up that E350 master cheap and can see with a little rework on the mounting it's a done deal. Parts stores around here didn't have the lines with different ends so I just had to get the right adapters, no biggee.

I just went to Autozone today and took a look at one of these E-350 masters. The one I was handed had a small and large resevoir (disc/drum). Does this make a difference if I have rear discs? I know the big thing with the Vette master is that it is ready for disc/disc. Did I just see the wrong master or is the fact that the E-350 master is so large, the small drum resevoir doesn't matter?

Originally posted by Mugsy
I just went to Autozone today and took a look at one of these E-350 masters. The one I was handed had a small and large resevoir (disc/drum). Does this make a difference if I have rear discs? I know the big thing with the Vette master is that it is ready for disc/disc. Did I just see the wrong master or is the fact that the E-350 master is so large, the small drum resevoir doesn't matter?

I have drums. I will say that I think if you disable your rpoportioning valve with the o-ring trick then it should supply enough to your rear discs. Most people who disable the proportioning valve on a rear drum to disc swap have good results with their rear brakes (regardless of master cylinder use - disc/drum vs. disc/disc). Have you done the proportioning valve trick already???

And it had no effect on the rears. I only have 33 TSL's with a stock D-30 front (93YJ) and 8.8 rear (w/ explorer discs). I can't stop at all and I haven't been able to for a while. I have been reading for months all of the posts about the E-350 and vette master's trying to decide which one to try. I might try the E-350 one just because it's cheaper. I just don't to get the adapter lines fabbed up and not have it work. My big concern was that the E-350 master looked similar (except for size) to the stock Jeep one.

Originally posted by Mugsy
I just don't to get the adapter lines fabbed up and not have it work. My big concern was that the E-350 master looked similar (except for size) to the stock Jeep one.

It is the same except for a larger bore and longer stroke. I used the cover off my Jeep one because the reman one I got leaked :D

The adapter lines were available to me at discount auto, pre-made. I'm guessing you can order them somewhere if you can't find them. They were like $2.50 per line. The master was $15 and you can use anything that looks similar to a Jeep/E350 master as the core.

have someone fully depress your brake pedal and then check the fluid level in your master cylinder. If it isn't pulling it dry then that size reservoir is large enough.

bigdude you would do well if you took the advice from the newbie "Tmartin" He is exactly correct in saying if you change nothing but the master cylinder, for one with a larger bore you will reduce your line pressure to the slave cylinders.
But you will gain volume that has nothing to do with stopping faster unless you are already short of volume. I suggest reading some hydraulic books!

curb squirrel newbie LMAO

jmancuso - if you read the post that started this all, the guy's got bigger brakes (slave cylinders) all around - just like I do. He's having to pump his brakes due to lack of volume. My pedal used to go to the floor in a hard stop. The answer to our problem is a master cylinder that pushes more fluid - like the E-350 M/C. I changed it and it works great. You can't argue with results.

Originally posted by jmancuso
He is exactly correct in saying if you change nothing but the master cylinder, for one with a larger bore you will reduce your line pressure to the slave cylinders.

I just reread my posts and nowhere did I contest him on that :confused:

Big dude,
Do you have the fitting sizes for the lines from the proportioning valve in a 88 YJ to the master cylinder you used? I'm lazy and it'd just be easier to ask for the sizes than try to fit a bunch o shiat in the store. Plus I don't have to take my YJ apart until I have all the parts that way. I want to try this upgrade. Thanx for the info btw, very useful.

Ben

Originally posted by jeepboyben
Big dude,
Do you have the fitting sizes for the lines from the proportioning valve in a 88 YJ to the master cylinder you used? I'm lazy and it'd just be easier to ask for the sizes than try to fit a bunch o shiat in the store. Plus I don't have to take my YJ apart until I have all the parts that way. I want to try this upgrade. Thanx for the info btw, very useful.

Ben

Sorry, no idea. I'll check in the garage for receipts or spare lines and see if I can dig it up.

Originally posted by jmancuso
bigdude you would do well if you took the advice from the newbie "Tmartin" He is exactly correct in saying if you change nothing but the master cylinder, for one with a larger bore you will reduce your line pressure to the slave cylinders.
But you will gain volume that has nothing to do with stopping faster unless you are already short of volume. I suggest reading some hydraulic books!

curb squirrel newbie LMAO

I don't have any hydraulic books laying around:zzz: so maybe you guys can enlighten me because this just doesn't make sense. If you take two jeeps with identical brake systems and one has the OEM master and the other a larger one such as the E350, you're saying that the OEM is going to have more line pressure? I mean when you push the pedal down on a larger MC you are pushing more fluid into the lines than are you with a smaller unit. This fluid just doesn't go *POOF* into never never land it fills the slaves and exerts pressure. So two identical brake systems, a larger displacement of fluid being pushed would stand to reason there would be an increase in pressure.

Hey if I'm wrong I'm wrong I don't really care but I'd like to know why other than, "just because".

Originally posted by jeepboyben
Big dude,
Do you have the fitting sizes for the lines from the proportioning valve in a 88 YJ to the master cylinder you used? I'm lazy and it'd just be easier to ask for the sizes than try to fit a bunch o shiat in the store. Plus I don't have to take my YJ apart until I have all the parts that way. I want to try this upgrade. Thanx for the info btw, very useful.

Ben
I used a 1/4" tube to 3/16" tube adapter and a 5/16" tube to 1/4" tube adapter and just used the stock lines.

I have hydraulic books laying around because I'm a degreed chemical engineer. But the thing is, I don't use 90% of the shit I learned in school :laughing:

In a closed vessel w/ a piston, if you exert the same force on a smaller area then you would experience a higher pressure. In a brake system you have an orifice for fluid to exit through, lines the fluid travels through, and cylinders that it fills. What the real issue comes down to is how much fluid you move.


You can apply X amount of force to a small amount of fluid, this will fill the calipers so much and exert force on the disc brakes. If you don't have enough fluid in the caliper cylinders to force them against the rotor, then your brakes suck. If your brakes are equipped with a valve that slows the return of fluid (depressurization of the cylinder) then pumping your brakes will allow you to keep moving fluid (in incremental amounts) to the caliper cylinders, eventually filling them enough that pushing the pedal will allow enough force to be transferred to the rotors for stopping (force is transferred through pressurization of the system).

Now you apply X amount of force to a larger amount of fluid (due to the larger master cylinder). The amount of fluid moved in this case is more than enough to fill the caliper cylinders and exert force on the rotor to stop (through pressurization of the system). Thus no pumping of the brakes.

From my understanding (and I could be wrong on this so please explain if I am) a vacuum booster just helps to multiply the amount of force you apply to the pedal. Thus you have to push less on the pedal to apply a given force to the fluid in the master cylinder. This makes braking seem easier if enough fluid is present, but does nothing to move more fluid if that is what's needed.

Therefore if you have larger then stock caliper cylinders (larger brakes basically), and you aren't moving enough fluid to them, you need a larger master.


Please feel free to correct me if I'm wrong. I was too lazy to get books out and research stuff :D

Originally posted by bigdude
I have hydraulic books laying around because I'm a degreed chemical engineer. But the thing is, I don't use 90% of the shit I learned in school :laughing:

In a closed vessel w/ a piston, if you exert the same force on a smaller area then you would experience a higher pressure. In a brake system you have an orifice for fluid to exit through, lines the fluid travels through, and cylinders that it fills. What the real issue comes down to is how much fluid you move.


You can apply X amount of force to a small amount of fluid, this will fill the calipers so much and exert force on the disc brakes. If you don't have enough fluid in the caliper cylinders to force them against the rotor, then your brakes suck. If your brakes are equipped with a valve that slows the return of fluid (depressurization of the cylinder) then pumping your brakes will allow you to keep moving fluid (in incremental amounts) to the caliper cylinders, eventually filling them enough that pushing the pedal will allow enough force to be transferred to the rotors for stopping (force is transferred through pressurization of the system).

Now you apply X amount of force to a larger amount of fluid (due to the larger master cylinder). The amount of fluid moved in this case is more than enough to fill the caliper cylinders and exert force on the rotor to stop (through pressurization of the system). Thus no pumping of the brakes.

From my understanding (and I could be wrong on this so please explain if I am) a vacuum booster just helps to multiply the amount of force you apply to the pedal. Thus you have to push less on the pedal to apply a given force to the fluid in the master cylinder. This makes braking seem easier if enough fluid is present, but does nothing to move more fluid if that is what's needed.

Therefore if you have larger then stock caliper cylinders (larger brakes basically), and you aren't moving enough fluid to them, you need a larger master.


Please feel free to correct me if I'm wrong. I was too lazy to get books out and research stuff :D

Could you not also accomplish the same thing if you need the same line pressure and just increased the stroke without increasing the bore?

You are correct in that the booster does just that. It boosts the force using atmospheric pressure to increase the force on the master. The problem with that is that atmospheric pressure is relatively fixed and to get more pressure, we have to go to larger diameter boosters to generate higher or sufficient line pressures with large bore masters.

I play with TJ's a bit and was surprised to learn that they generate over 1200 psi at the caliper with the stock system. At least I know why my wife's Wilwood calipers squeak now. :)

Originally posted by mrblaine


Could you not also accomplish the same thing if you need the same line pressure and just increased the stroke without increasing the bore?



Sure - can you tell us which master cylinder does that? Also, you'll have to redesign the brake pedal bracketry and the stroke of the actuating mechanism on the YJ since, as I indicated many posts back, with my Dodge Power Wagon front discs and my Ford 11" drums in the rear my pedal was pretty much to the floor on hard braking. Coming off of some obstacles I was unable to completely stop the thing. With the E-350 M/C I can lock them up with the pedal halfway to the floor.
You guys are over analyzing this. Have any of you guys talking about line pressure actually tried an upgrade to a larger M/C? You've got 2 guys who have practical experience who can tell you that the E-350 upgrade works. If you want to keep discussing hydraulic theory, knock yourselves out. My brakes are done, they work, I'm on to solving other problems. If anyone reading this has upgraded to larger brakes and has problems, I suggest spending the $20 and an hour of your time to see if this solves your problem before digging into more expensive and complicated options.

Originally posted by withamc


Sure - can you tell us which master cylinder does that? Also, you'll have to redesign the brake pedal bracketry and the stroke of the actuating mechanism on the YJ since, as I indicated many posts back, with my Dodge Power Wagon front discs and my Ford 11" drums in the rear my pedal was pretty much to the floor on hard braking. Coming off of some obstacles I was unable to completely stop the thing. With the E-350 M/C I can lock them up with the pedal halfway to the floor.
You guys are over analyzing this. Have any of you guys talking about line pressure actually tried an upgrade to a larger M/C? You've got 2 guys who have practical experience who can tell you that the E-350 upgrade works. If you want to keep discussing hydraulic theory, knock yourselves out. My brakes are done, they work, I'm on to solving other problems. If anyone reading this has upgraded to larger brakes and has problems, I suggest spending the $20 and an hour of your time to see if this solves your problem before digging into more expensive and complicated options.

I was basically distilling what BD said. I was not being argumentative.

I do agree that if it works, no problems and it is worth a small investment of time and money. Sorry for confusing you.

To answer your question about line pressures and upgrades, then yes, I have played that game and will continue to do so.

I have done Wilwoods and stock booster with upgraded master on a TJ with modified stock knuckles.

Hydroboost with new bigger master on ZJ with four wheel discs and stock calipers.

TJ with WJ dual piston calipers, 11" caddy dual diaphragm booster, bigger master and Explorer rear discs.

TJ with Wilwood rears, stock booster, bigger master, and stock fronts.

TJ with Cobra PBR dual piston calipers, stock booster, bigger master and Explorer rear discs.

Cherokee with Second Generation WJ crap and stock booster with upgraded master and Explorer rear discs.

MP dual diaphragm 10" booster with stock components in front and rear Explorer discs. (worst one of the bunch)

I do have a little experience and was just looking to add to my knowledge base by distilling what BD said into more palateable terms. Every little bit of knowledge helps and I was enjoying the thread very much.

AMEN REVERAND BIGDUDE AND PASTOR WITHAMC! Thanks for the explanation, us country folks get a little dumbed down at times staring at all this corn.:fj: The rest of you "unbelievers":crybaby2: can go on and waste your time piddling with your pushrods and stroking your theories, I'll put my money into something that has been tested with REAL world experience.:flipoff2:

mrblaine - What worked? What was involved? I'm more interested in the practical applications like a low cost booster upgrade that's fairly easy to accomplish.

Originally posted by withamc
mrblaine - What worked? What was involved? I'm more interested in the practical applications like a low cost booster upgrade that's fairly easy to accomplish.

The easiest and most effective so far was the upgraded booster and master on my TJ. The stock booster is fairly different where the master pushrod is configured, so most normal master swaps are difficult. You are stuck with little known stuff from most Chrysler crap.

I just had a 85 DeVille fwd booster re-rodded with the TJ brake pedal rod and bolted up a Vette drum/disc master. Very easy.

I now had wonderful brakes with ample volume and very high line pressures to increase the clamping force needed to stop easily.

Unfortunately, with the high line pressure came the early demise of various brake components. Wheel cylinders don't live long above 600 psi. The stock front pads would easily bend the ears over as would the rear shoes at the pivot. The backing plates went next. I could stop anywhere, anytime, and in a very short distance. I just destroyed the stock components in the process.

I then upgraded to rear discs and a corresponding disc/disc master. Much better as far as durability went, but that still left the front pad problem. I put on the WJ dual piston calipers and now have too much booster for the master. It stops well, the pedal is just too spongy for my taste. I need to increase the bore of the master to compensate and hopefully not get so big that I reduce line pressure too much.

So far the best working system with the least amount of tinkering has been the hydroboost in the ZJ. Kind of a pain to install, but not horrible. The only tinkering we had to do was boost the steering pump and half pedal locks everything up quite nicely.

The pedal height is a bit low and can be remedied with a longer booster to pedal rod, but at the time we needed to hurry a bit and decided to live with it. Mostly nitpicky stuff though.

All of the crap we have tossed in has worked very well with the exception of the MP stuff. Just not enough booster. I am currently doing the finishing touches on the Cobra set-up and will have some results soon.

I am taking the Wilwoods off of my wife's and swapping on the WJ knuckles for higher steer and adapting the Cobra PBR's onto them. Just a simple matter of backspacing the rotor to line up in the caliper. The caliper adapter bolts right up to the WJ knuckle. Imagine that!

Originally posted by withamc

I used a 1/4" tube to 3/16" tube adapter and a 5/16" tube to 1/4" tube adapter and just used the stock lines.


Thanx =)

Ben

Thanks you guys for the info. I have been looking for a cheap fix..

Originally posted by withamc

I used a 1/4" tube to 3/16" tube adapter and a 5/16" tube to 1/4" tube adapter and just used the stock lines.

Sorry to bring back the dead, but I picked up an E350 master the other day, but couldn't get the adapters listed above. We did find some thing simliar to them, but they didn't bolt to the master (either side).

Can anyone confirm the above adapters? Are the dimensions of the NPT on the fitting, or of the tube that the fitting comes on?

Any help appreciated, I'd really like to get new tube from the master to the combo valve, can someone let me know what size the two outlets of the E350 master is, and the two inlets of the combo valve are? I screwed up and left both parts at home, and I'd like to pick up the tube after work, THANKS

Chad Lueders