Thread: brake problem

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Hi all!! Had a panic stop sat. night going about 50 mph,the back brakes seem to lock up and the rear of the car came right around in a 180(facing traffic),miss the car that pulled out(she came over to apologize,did not see me coming)and nobody was behind me. the car is a 32 glass three window(2600lbs)302 ford with a 5 speed,the front brakes are from a 1956 f1 truck all new parts and the rear are 10.5 ford drum brakes. the master cylinder is a 1963 chevy truck dual set up(brake and clutch),tire are bias ply,road was dry but temps were in the 20s.question is would putting a proportioning valve to the rear brakes help slow the rear from locking up?and can it be put on a car with single master cylinder?. the pedal is hard and the car does not pull side to side. thanks Pete

Yes, you could put an adjustable proportioning valve in the line to the rear brakes to keep them from locking up. The valve would restrict the amount of pressure to the rear brakes, thus giving you a better braking balance front to rear. I use a Wilwood in my car.

Keith

Next time that happens, don't ease off when the rears lock up, slam the pedal harder and the fronts will lock up too. You'll stop quicker and straighter.
The best fix would be bigger front brakes. Get some front drum brakes from a '70-'72 pickup, they're wider.

the adjustable valve, http://www.summitracing.com/parts/WIL-260-11179/ works very well and is an easy install.

Originally Posted by Weasel Diesel

the adjustable valve, http://www.summitracing.com/parts/WIL-260-11179/ works very well and is an easy install.

Thanks for the replys!! I got a chance to test a little today(sunday morning and empty school parking lot). back brakes definitely lock up every time so i will try the proportioning valve to the rear brakes,could not get the front brakes to lock up but now i know what to expect i can control the car alot better under hard braking. thanks again Pete

Now don't forget, if your master cylinder is lower than the wheel cylinders, use residual valves. That valve I referred you to earlier works great though. Here's my valve's positioning and setup;

Here is HOW I did mine



I have the same F-100 front brakes and Ford Bronco 10.5 rear brake setup ... and my car stops GREAT ... with the valve adjusted properly. It takes a little time and a few attemps to get right ... but worth the effort.

Deuce

You could change the size of the wheel cylinders---go smaller on rear and then maybe one size bigger on the front

Originally Posted by jerry clayton

You could change the size of the wheel cylinders---go smaller on rear and then maybe one size bigger on the front

Jerry, not saying it would not work, but chances are you'd still want the adjustable proportioning valve like Weasel & Deuce show in their photos unless you just happen on the ideal size difference, and he needs the residual valves for sure if the master is low. I'd try the proportioning valve first before spending money on new wheel cylinders. Just my $0.02...

try this thought----a single master cylinder / not late model duels----

a porportioning valve will cut down the total braking from that one very limited source by reducing the force to the rear

Changing the wheel cylinders is cheap, effective and leaves the total brake effort available---if after altering the rear DOWN by 1/8 inch , he wants more front, he can increase fronts by 1/8 inch--probably cheaper than buying a por valve that has 3 possible leak points

Originally Posted by jerry clayton

try this thought----a single master cylinder / not late model duels----

a porportioning valve will cut down the total braking from that one very limited source by reducing the force to the rear

Changing the wheel cylinders is cheap, effective and leaves the total brake effort available---if after altering the rear DOWN by 1/8 inch , he wants more front, he can increase fronts by 1/8 inch--probably cheaper than buying a por valve that has 3 possible leak points

Yup Jerry, easy and it works.

We had the same problem (but on the opposite end locking up) on our drag race VW which has small front and big rear tires. It's been stopping from 120 mph with drum brakes just fine for the past ten years after the wheel cylinder size change.

Originally Posted by jerry clayton

try this thought----a single master cylinder / not late model duels----

In about 1968 or so ... well over 40 years ago ... the feds mandated dual master cylinders on all Cars for a good reason ... SAFETY.

I will not own a single cylinder master cylinder on a street car ... and prefer NOT to have one on a race car.

Way back I had a brand new '79 Mustang with the TRX suspension. It would swap ends on a panic type stop. Ford did everything but change the rear wheel cylinder size - except with new 1" OEMs. They also did a new master cyl, replaced the springs, shocks, loosened the entire suspension - then gave up, saying they had done all that they could and called it a day. They didn't do their own in-house research. The '80s had a 7/8" rear wheel cylinder which I found out accidentally. For about $30 I did them myself, tightened up the suspension to spec and replaced all the rubbers with the original TRX plus called the NHTSA with my complaint. I eventually was reimbursed after a recall was finally issued. Those 1/8" smaller cylinders - did the job

Deuce

I think you misread ---the thought to be considered by everybody trying to come up with a fix is that this vehicle has a single master---the dual part is that one side is for clutch and other side for brakes---

And the times that the federal mandated master has saved lives??? more often than not people are driving around with one half there brake system bad, a low pedal, and keep driving--eventually causing a serious mis hap

Nice setup Deuce... What type of line bender do you have to get such crisp tight bends?? My bender has a wide radius ( as you can see).