WHAT IS THE REASON FOR USING THE MONTE CARLO CALIPERS IN THE REAR DISC SWAP RATHER THAN THE 90'S CHEVY CALIPERS MADE FOR THE CHEVY ROTORS? DONT HAVE A MONTE CARLO CALIPER HERE, BUT IT SEEMS A TRUCK CALIPER WOULD BE STRONGER..... CLEARANCE ISSUE MAYBE?

MATT

Originally posted by FIXXXXAH
CLEARANCE ISSUE MAYBE?

MATT

most likely

It also could be kind of an urban myth.

The bracket was designed for this application years ago, the GM caliper was an easy score and the bracket has spawned that "generation" for years afterwards.

AS the long as the arc radius of the rotor travel matches the caliper placement, you are good to go.


Any caliper could be used as long as it is positioned properly with the rotor.

$.02..................
:p

From what I recall, the Monto Carlo calipers have the ablility to have an ebrake setup with cable at the axles. So people going to other t cases other than 3 spd and non-split 4 sped cases can still have an ebrake option as well as a 4 wheel disk setup.

Originally posted by dieselcruiserhead
From what I recall, the Monto Carlo calipers have the ablility to have an ebrake setup with cable at the axles. So people going to other t cases other than 3 spd and non-split 4 sped cases can still have an ebrake option as well as a 4 wheel disk setup.

No, Caddilac calipers have the e-brake option...

And when you run the caddy calipers you really should get a larger bore master cylinder.. They have a larger piston than the montecarlo do..

I know the monte calipers are REAL fawking close to my 15" wheels... and they're cheap!

YEH, I DONT THINK THE BIGGER CALIPERS ARE WORTH THE 16" RIM... THE MONTE CALIPERS WILL DO FINE I THINK. NEED TO FIND SOME TO TURN IN FOR CORE'S.

hey Jason,

What year caddilac callipers work w/ the GM brackets? do you know of any yards around here that would have them? I'll probably go w/ the fj80 master you have since I need more braking power anyways.

Thanks!!

The reason for the MC calipers (referred to as 'small GM metric' IIRC) is because the piston size is small enough that with a prop valve you can balance your brakes (just barely !!!) If you ran one of the truck calipers, you would have too much piston area, too much clamping force, too much rear braking and a rig that would be wrecked and rolled the first time you panic stopped on a wet road....

Jim

Originally posted by TLCObsession
The reason for the MC calipers (referred to as 'small GM metric' IIRC) is because the piston size is small enough that with a prop valve you can balance your brakes (just barely !!!) If you ran one of the truck calipers, you would have too much piston area, too much clamping force, too much rear braking and a rig that would be wrecked and rolled the first time you panic stopped on a wet road....

Jim

Unless you ran a proportioning valve like you should anyway ;)

Fit is a good reason. Also because the street racers were using what they readily had. Weld on brackets are very easy to find for that caliper...

BTW, if you ran a larger piston you have to get a larger MC to get the same clamping force.. So what you end up with is needing to pump the brakes to build up the pressure. which is why Sixty wants to put a 80series MC on his cruiser with the eldorado calipers.
You do not get more clamping force with a larger caliper piston if you are running a MC that is too small for it.
And the eldog calipers fit in the exact same brackets as the MC do..

:)

Jason -

1. He was talking about running newer truck calipers - big piston or big surface with dual pistons.... The Eldo calipers work well because they are for the rear of the vehicle, and are also designed smaller for that reason.

2. Clamping force - You may need the volume to move it, but the pressure is the same throughout the system.

3. If you reread my post, I mentioned the prop valve. I don't know about the rest of you, but with the Summit/Wilwood valve, I have it cranked all the way down, and it is just enough to balance the brakes - note that my setup has been until this point:

35" tire, Softtop, and running the larger (mini IFS calipoers up front. With a hard top I know you can balance the brakes. Ask me after Saturday how the balance is with the 37's.....

With a soft top, regular mini calipers and 33's, my buddy still locked the rears first until we put a little boneyard proportioning valve in line with the adjustable unit.

Jim

Jason I might not be getting your explination, but you "will" get more clamping force with a smaller master and a larger "slave" or in this case caliper you shouldn't need more volume it takes a very small volume to ingage the breaks what you are mainly doing when you push the brake is creating pressure not moving volume.
I think they use the smaller GM calipers because they do have reasonable bore size so they can still be proportioned down as not to have too much clamping force on the rear sence the rear only dose about a third of the breaking anyhow.

Small bore to big bore more pressure less movement
Big bore to small bore more movement less pressure

Originally posted by TLCObsession
Jason -

1. He was talking about running newer truck calipers - big piston or big surface with dual pistons.... The Eldo calipers work well because they are for the rear of the vehicle, and are also designed smaller for that reason.

2. Clamping force - You may need the volume to move it, but the pressure is the same throughout the system.

3. If you reread my post, I mentioned the prop valve. I don't know about the rest of you, but with the Summit/Wilwood valve, I have it cranked all the way down, and it is just enough to balance the brakes - note that my setup has been until this point:

35" tire, Softtop, and running the larger (mini IFS calipoers up front. With a hard top I know you can balance the brakes. Ask me after Saturday how the balance is with the 37's.....

With a soft top, regular mini calipers and 33's, my buddy still locked the rears first until we put a little boneyard proportioning valve in line with the adjustable unit.

Jim

Quite a few people that have run the caddy calipers maintain that they have to pump the brakes to get enough fluid to engage the calipers. They are actually larger than the MC calipers.

And you are very true. The hydraulic pressure does not change. it is not compressable. However it needs a bunch more fluid than a cruiser MC can provide.

My bad, I missed that part. You really have had that much trouble with the rear end locking up?
I don't, but my fronts have always clamped very well.. And I have 38.5's

Interesting..


Pontiota,
No matter what you do you lose some clamping pressure over time. Even with a residual valve. Which is why pumping the brakes has worked to make the caddy calipers engage.

And you are correct. Ease of adaptability and the fact that they do not have to clamp as hard as the fronts do to stop the truck..


And it goes,
small bore/large bore less movement same pressure
large bore/small bore more movement same pressure.
Pressure is dictated by the force exerted by your foot on the pedal (assisted by the booster most of the time) Volume is what makes the difference here. You have to add more volume to make up the difference in movement. You really have the same amount of force it just is not acting on the brake pad... A force needs something to work against..

The biggest thing here is to have a balanced system. Use a MC designed for disks and it will be easier.

Jason your right that force is the pressure your foot is applying to the brake peddle but were you go wrong is the force is multiplied by the larger bore in the caliper it works the same way as leverage on a pry bar if you had a 1in bore to a 10in bore you would increase your pressure 10 x's but you would decrease your movement of the piston 1/10 your brakes have something wrong with them if you need to pump them up it could be that the rotors are warped to the poin they are backing off your calipers but once you remove your foot the brake pad should rest rubbing against the rotor and full break pressure at the caliper takes less than about a 1/32in of movement or about the thickness of a dime.

Actually it would increase your pressure by 100 time. it is the surface area of the bores that matter (.79" to 79" on a 1" to 10" bore) :rolleyes: :D

I think the reason the bores will back off is that there are small springs in the caliper that will back the piston off if I'm not mistaken.

Originally posted by pontiota
Jason your right that force is the pressure your foot is applying to the brake peddle but were you go wrong is the force is multiplied by the larger bore in the caliper it works the same way as leverage on a pry bar if you had a 1in bore to a 10in bore you would increase your pressure 10 x's but you would decrease your movement of the piston 1/10 your brakes have something wrong with them if you need to pump them up it could be that the rotors are warped to the poin they are backing off your calipers but once you remove your foot the brake pad should rest rubbing against the rotor and full break pressure at the caliper takes less than about a 1/32in of movement or about the thickness of a dime.

Thinking about it you are right. The larger bore will give you more pressure. Kinda like the difference between the 2" bore hydro ram and a 1" bore. Although it is slower....

I don't have to pump mine. It is a concern that mini drivers have when they use the eldo calipers.

well to answer the original Q, you will run the small GM calipers cause thats what the brackets are made to fit, the truck calipers mount holes are farther apart. use your truck calipers as cores for rebuilt small bore ones.

doesnt have to be monte, any small bore GM of similar year works.

in this case caliper you shouldn't need more volume

well yes and no,, though the cruiser master will keep up with the GM caliper, the pedal will travel farther to pump the required fluid. if you get a larger bore master, the pedal will not travel as much because you are pumping more fluid.

RHINO- I'M GOING TO BE RUNNING GM HYDRO BOOST, AND FABBING MY OWN BRACKETS, SO I COULD MAKE THEM TO FIT WHATEVER I NEED. WHAT I'M STUCK ON IS BORING OUT THE ROTORS OR TURNING DOWN THE AXLE SHAFTS. LEANING TOWARDS THE AXLES SHAFTS CAUSE I THINK I WILL BE MORE LIKELY TO TORCH A ROTOR THAN SNAP A REAR AXLE.

I'M NOT GOING TO GO WITH THE TRUCK CALIPERS CAUSE IM NOT FOND OF THE 16" RIM, AND THE MONTES ARE CHEAP...

MATT

But when you break an axle shaft, you won't be able to get one from any cruiserhead on the trail or someone who has one at home ..... I have had my rotors on for 5 years, and they look like new...

i second tlcobsession, unless you will have a spare axle turned down as well and carry it with.

as far as truck calipers, yes they fit in a 15" rim, all the trucks had 15" rims till a few years ago. the reason for the monte is mostly due to the small bore.

Yeah, what TLCObsession said.. 'cuz it's quicker, easier, and less messy to buy a rotor at the parts store and have it turned, than it is to pull the back end of the cruzah apart and bring that in...

WELL, THE REAR END IS ALREADY DOWN TO THE HOUSING SO ITS NOT TOO BIG OF A PROBLEM, YOU GUYS REALLY THINK YOUR GOING TO BE MORE LIKELY TO SNAP A REAR AXLE THAN TO TORCH A ROTOR? THE CRUISER AXLES ARE PRETTY BURLY, I HAVENT HEARD OF MANY PEOPLE BREAKING THEM, ESPECIALLY DOING MY KIND OF WHEELING [NOT A DEDICATED HARDCORE TRAIL RIG] SO IT SEAMS IT WOULD MAKE MORE SENCE TO DO THE AXLESHAFTS.

RHINO- ARE YOU SURE? THE TRUCK I LOOKED AT [MY BROTHERS OLD TRUCK, EARLY 90'S 4X4 SHORT BED STANDARD CAB CHEVY] HAS 16'S AND ITS PRETTY CLOSE TO THE CALIPER... STOCK RIMS.

Turn the rotor... Cheaper and easier in the long run. You can deal with a bad rotor for a lot longer than a broken axle on a cruiser.
Drive on a bad rotor and then drive on a broken axle shaft. They are burly but they do break... It is not a matter of which one will go first. it is more of a matter of which one will be the bigger PITA to change when you are out on a trail stuck......
I know lots of people that carry spare axleshafts. And of those people I do not know one that has turned down the center of it for disks...

If you're really worried about the economics and availability of replacement rotors for the standard Monte Carlo RDB conversion, get four rotors milled out to 4.185" at the same time, then you'll have two spares and probably get a better price than doing two, then one or two later on.

The monte carlo rdb swap (http://www.birfield.com/~morgan/tech/rdb/) just plain works.

Morgan

Originally posted by TLCObsession
Jason -

3. If you reread my post, I mentioned the prop valve. I don't know about the rest of you, but with the Summit/Wilwood valve, I have it cranked all the way down, and it is just enough to balance the brakes - note that my setup has been until this point:

35" tire, Softtop, and running the larger (mini IFS calipoers up front. With a hard top I know you can balance the brakes. Ask me after Saturday how the balance is with the 37's.....

With a soft top, regular mini calipers and 33's, my buddy still locked the rears first until we put a little boneyard proportioning valve in line with the adjustable unit.

Jim


I dont quite understand this... With the willwood valve turned all the way in, you should be getting the most rear bias(ie most availible effort to rear), but you go on to say you can barely balance them with a soft top but they will be okay with a hard top??? That seems like there is too much rear brakes, and if the willwood valve is okay with a hard top as you assume and I can verify, why dont you try backing the knob out and reduce the rear bias?

The root of the volume problem comes from the fact that no matter how hard you try to eliminate all the initial pedal travel you cant, because the c-clip axle shaft moves in and out a small bit(1/32" maybe.) even with a floating GM caliper the pads can be pushed back into the caliper housings, requiring a bit of fluid movement just to press them against the rotors. A residual valve can help but it is an imperfect system, one you can't find on an OEM design anywhere I know of. Assuming a 2" bore diameter of each rear caliper and a .75" M/C bore you will need .43" of travel of the master cylinder piston just to get both calipers pads to contact the discs (from the 1/32" away). This equates to about 2.6" of travel on a 6:1 pedal ratio(no idea what stock is but I bet is is near that...)So, by the design of the master cylinder, your front brakes wont get any real pressure until the rear pads are up against the rotors(or the rear piston bottoms on the front), and that is not until 2.6" into the pedal throw. A bigger bore M/C hides the problem by moving more fluid for the pedal travel and because of the ratio of the bore diameters now you required pedal effort for similar braking effort now just got bigger.

RHINO- ARE YOU SURE? THE TRUCK I LOOKED AT [MY BROTHERS OLD TRUCK, EARLY 90'S 4X4 SHORT BED STANDARD CAB CHEVY] HAS 16'S AND ITS PRETTY CLOSE TO THE CALIPER... STOCK RIMS.

i was referring to the earlier trucks with 15" rim.

brett,, i'm not gonna quote the whole thing you posted, but the second half sounds about like my scenario when i tried the cruiser master.,it worked but there was alot of pedal travel..
call it "hiding" the problem if you like, but when i upgraded to a bigger bore master (1") it took the pedal "feel" right where one would expect it to be, it is great to drive-err i mean stop, very little effort. completely happy with the end result.
BTW i have not needed a prop valve on my rig, i have done thorough testing on all types of terrain even a sandy over hardpack hill test, and do not seem to lock up either axle quicker than the other, maybe i was lucky?

I did not mean hiding in a bad way... If it works, great! I have not had the best luck with it, even with a bigger bore M/C... Just my experience. I have changed to the bigger bore M/C and it made the braking effort to great for my liking...

I just upgraded to a master and vac-assist out of a 97 tacoma, I have disks on all four, new big bore calipers from a 95 fourunner if front and montie carlo calipers in the rear. My brakes were ok before, sometimes they would work great, and somtimes it seems I would run outa vaccume assist, I could still lock em up but it took alot more pressure. Now with the MC/VA out of the Taco the brakes are alot more responsive, but it still seems that the are not always the same. I think this must be the semi-float rear bumping the pads in the caliper out , and as a result more brake fluid/ brake pedal is required to stop. I hear you can add a 2# residual valve on the rear, this will help keep the pads in contact with the rotors.
Has anybody done this? I hear you can get one from Wilwood for around $15.00, it's used in circle track racing when your MC is lower than your calipers, it stops the fluid from bleeding back into the MC via gravity.

-Scott

I run a 2lb residual valve in mine. Never ran without it. So I can't really tell you the difference.
We'll see the difference between the FJ80 master and the 40 master when it is rolling again though..

I believe the master from the Taco and the Fj80 are the same one, one inch boar single resivour, aluminum housing, there is no residual valve built into it as far as i can tell.

-Scott

Originally posted by Cruzilla
I believe the master from the Taco and the Fj80 are the same one, one inch boar single resivour, aluminum housing, there is no prop valve built into it as far as i can tell.

-Scott

I would agree, I heard that there was but for the life of me I can't find one...


TLCobsession, when you did your rear Disk conversion did you remove the 10lb residual valve out of your stock cruiser master???

It might give you an answer to why you lock up easily...
:confused:

Brett -

I think you somehow missed the point - the brake system works fine - just barely:
- plenty of brakes
- pedal effort is great
- stopping power is great

But - the bias is just barely OK. I have the bias (prop valve) set to the maximum restriction - IOW the most reduction in rear pressure possible.

The bias is needed because the swept area required for the front is much smaller than what is needed for the rear.

The reason I brought the hardtop into it is the same reason that the wagons and mini's run a load sensing prop valve. Weight in the rear required more rear brake (less bias).

A few of the reason's that I need less braking in the rear are:

- normal bias as explained above
- fairly light rear load (2 ammo boxes of tools, fluids, F axles/birfs, high lift and some other light stuff)
- a very soft suspension (more dive under hard braking)

Pretty basic. But it goes back to one reason that the Monte Carlo calipers are used - one of the smallest pistons/swept area, widely available (= cheap), easy to bracket and (in order to reference one of your points)

- floating design - great for use with a clip axle that allows the caliper to float to account for:

- wheeling crap/debris
- end play because of the c-clips (this is pretty minimal in reality because of the gyro effect of a very heavy wheel tire)

Hope this clears up a few misconceptions.

Jim

Jim,
As for the proportion valve adjustment, I think that is where I misunderstood you...Sorry, that was the root of my question as to why it was locking up. By cranked down, I thought you meant turned all the way opposite of the "increase" on the knob.

As for the floating rotor issue, I can get plenty of play(1/32") in my axle, and it can push out the pads. The gyro effect of the wheel is nil in relation to the axis of its rotation(which is the diection of motion of concern). Grab a bike wheel and check, it is easy to move in the direction of it's rotational axis. where this effect comes into play is turning it...
Plus there is plenty of loading from cornering loads to move it in and out...

I do agree the floating caliper is better that a non floating for this example, and with a residual valve it can be made better, but it still is not a perfect system...

-Brett