Would someone please recommend a brake master cylinder for an '82 Chevy S-10 race truck that now has 4-wheel disk brakes?

This truck has the stock, GM 'Metric' calipers on the front and GM locking 'Caddy' calipers on the rear. The rear calipers have parking brakes and came with the brake kit I installed when I put in a Ford 9" rear end.

The current master cylinder is supposed to be for I believe an '84 Eldorado, which I ass/u/me'd would be suitable for rear disks, thinking that all the Eldorados would have rear disks in the same year as the calipers I have.

I don't know for sure what the M/C bore is. I do still use the stock brake booster and have not yet converted to manual brakes.

I don't believe I'm getting proper pressure and volume to the rear calipers, but I'm going to semi-permanantly plumb-in a brake pressure gauge to verify.

I have the proportioning valve bypassed, but have an adjustable Wilwood unit on hand to install.

The front brakes are getting about 1,200 PSI.

I have thought of trying a master cylinder for a C-3 ('68-'82) Corvette, which I know to be for all-disks.
I'd even thought too about taking the whole booster/master cylinder combo from a Chevy Trailblazer (4-wheel disk) and installing that, but the pushrod to the brake pedal is much shorter.

One of the very best racers at my 'home' track claimed that the vast majority of racers use a Mopar brake master cylinder, but I could not get why they do.
Can anyone clue me in on what is good about the Mopar master cylinder?
Would it bolt up to the mounting studs I have?

Thank you much!
Troy

the "mopar" master cylinder is the go to MC for race cars with aftermarket braking systems and installed by most professional chassis builders.



That said, it can be purchased from Wilwood, strange, NAPA, etc.

http://www.dragstuff.com/techa...cingMasterCylPN.html
Here;s a list of mopar MC's and their bore. Mopar MC's are popular because they are aluminum and have screw on caps. You can cross the #'s and buy them most anywhere pretty cheap.
If you go full manual you need to measure your brake pedal ratio and get it 6:1 or better. You also have to be very careful how you make a pushrod so that there is absolutely positively no way the rod could ever pull out of the MC and fall out.
I would throw those rear calipers as far away as you possibly could. They never worked properly on street cars and the emergency brake in the caliper will screw with the adjustment.

My Camaro has 4 wheel disk brakes. I use a master cylinder from an S10. I have no problems getting enough brake pressure to slow down. My brakes have been converted to manual brakes by relocating the pushrod on the brake pedal 1" higher for more mechanical advantage. This also allows a straighter push for the rod into the master cylinder.

I have no idea what the bore size is of the master cylinder that I use.

I ended up with a stock master off 78 Malibu with manual brakes on my 4 wheel disc setup using 4 metric calipers. Just be sure to remove the residual pressure valve from the rear brake port if present.Youll know the rear brakes will drag if it has it.I would think the stock metric master for power brakes would work as well.

https://www.summitracing.com///parts/WIL-260-4893

this is the master cylinder on my Firebird with 4 wheel Mark Williams disc brakes, This 1.063" bore MC was originally installed by MPR in 2004 and replaced late last year.

I'm grateful to you all for the advice and for the very helpful links; thank you.

I may have to follow Eman's advice and discard the GM locking 'Caddy' rear calipers. At the time I bought the kit from Right Stuff years ago I thought I should have mechanical brakes as a backup, but they have turned out to be a huge PITA, in spite of rounding up every bit of information I could about them.

The e-brakes need to be adjusted just so I am told before you can even bleed them.

I would likely replace them with an ordinary GM 'metric' caliper like is stock on the front wheels, but I may need to find different brackets to adapt them to the 'big Ford, new-style' axle housing ends.

The GM 'metric' calipers I believe have 2.5" bores; I reckon I may need smaller bores in the back and/or an adjustable proportioning valve.

One more of what might sound like a dumb question; did car manufacturers ever use the same brake master cylinder for both disk/disk and disk/drum applications, and then used different metering/prop valves?

BTW, in case anyone is curious, older S10 trucks like mine have an extra hole drilled in the brake pedal arm, to give what I guess to be a 6:1 ratio for manual brakes.

Thanks again!
Troy

If I remember correctly, because it was a long time ago, the master cylinder I grabbed from an S10 was for a truck with manual brakes.

quote:

Originally posted by Bad Nusz:
I may have to follow Eman's advice and discard the GM locking 'Caddy' rear calipers. At the time I bought the kit from Right Stuff years ago I thought I should have mechanical brakes as a backup, but they have turned out to be a huge PITA, in spite of rounding up every bit of information I could about them.

The e-brakes need to be adjusted just so I am told before you can even bleed them.

I would likely replace them with an ordinary GM 'metric' caliper like is stock on the front wheels, but I may need to find different brackets to adapt them to the 'big Ford, new-style' axle housing ends.

If this is a race only truck, my advice is to throw your entire brake system in the weeds starting with the power brake booster and put a brake system on it designed and intended for drag cars from Strange or Mark Williams.

I did what 1320racer is saying on two drag cars. This is the only safe way to proceed.

and the least expensive in the long run.

Thanks, guys; at this point I'm likely to just get a whole new system.

The K-Car master cylinder was the early mass produced, lightweight, compact master cylinder.
Being for a front drive car the balance is 50/50 because of the front drive LF/RR - RF/LR brake plumbing scheme, so it's effectively the same as the Corvette style units. Mounted in the stock location no residual valve is necessary, the differential or bias valve is also not necessary, you want the most brake action on the hot sticky rear tires anyway. Ditch the power booster anyway unless you're driving with hand controls, power brakes have no business in a performance car.

Put together what you have and see how it is, it won't cost any more than a Autozone master cylinder and some brake line.

Whatever you do, PLEASE make sure that your pedal rod is positively retained in the master cylinder at all times.

Raybestos MC39034 $41.79 at Rock Auto. It is a 2-bolt mount so you will have to fab an adapter plate. This is the old Mopar design that works well, Strange and other $$$ MC's look identical.

Thank you for all the great responses, guys.
T.

quote:

Originally posted by 1320racer:
https://www.summitracing.com///parts/WIL-260-4893

this is the master cylinder on my Firebird with 4 wheel Mark Williams disc brakes, This 1.063" bore MC was originally installed by MPR in 2004 and replaced late last year.

Ed, does that suggested Mopar master cylinder have 3/8" x 24 ports, to accept 3/8" brake lines without adapters?
Thank you.

Thank you for all the great input, guys.

I think I understand now for one thing why the Mopar master cylinder is so frequently used:

*Many race cars are Mopars anyway
*Custom race car builders can stock fewer types of master cylinder, and may have settled on one, the Mopar units, somewhat arbitrarily.
They seem to have become the standard, 'generic' brake master cylinder.
*I like the screw-on caps on the reservoirs of most.
*New units seem to be cheap, plentiful, and readily available.
*It seems that a wide range of bore sizes can be had, but all seem to have the same 'form factor' for installation, and interchange well.

Did I miss anything? ;^)

quote:

Originally posted by Bad Nusz:


Did I miss anything? ;^)

It got popular because it was one of the first aluminum master cylinders (lightweight), that's all it really has going for it.



.

Thanks for all the input, fellas.

I may need a 1 1/16" bore MC, and GM can't seem to fill that need.
T.