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-   -   Brakes pull right, Brakes pull left, I want to stop straight. (http://www.hotrodders.com/forum/brakes-pull-right-brakes-pull-left-i-want-stop-straight-93960.html)

57 Chevy 07-17-2006 07:27 PM

Brakes pull right, Brakes pull left, I want to stop straight.
 
Quick history, 57' Chevy with 69 GM (Camaro) ft. disc, 57' rear drums, 79' Vett booster and M/C with 72' Nova proportioning valve. All worked great until the M/C went out. I replaced it with a new Vett unit. Now the brakes are sensitive, like the E-brake is part way left on. On slow stops it's straight, but on high speed stops it pull left OR right (scary). I don't know if it's the brake sys. or the 605 P/S box is going out. (Kinda like bump steer with the brakes.)
I don't know if the M/C has a 2lb./ 10 lb. or 2 lb/ 2 lb or no checkvalves.

57 Chevy 07-20-2006 07:27 PM

I see that a bunch of people have looked at this post, but no one has any input. :confused: :pain:

30desoto 07-20-2006 08:57 PM

57 Chevy

I am going to take a gander at answering your question.
1. Are you still using the proportioning valve from the 72 nova?

2. Your new master cylinder is setup for disc brakes front and rear.

3. You must have a 10lb residual valve for the rear brakes in your setup.

4. You should also have a 2lb residual valve for the front brakes.

The proportioning valve adjust the pressure between the front and rear brakes so that your rear brakes do not grab before the front, this maybe bad and causing your problem. If you do not have a 10lb residual valve for the back this will cause your rear brakes to grab continuously and/or feel like the e-brake is dragging. The 2lb residual for the front brakes keeps a constant pressure on the front. If anyone of these problems are not working correctly you will have problems. Now there are some people here that may disagree with my thought process and I will not question them but I would check your system out. A place that has good prices that I am fond of is on this link---http://www.zigsstreetrods.com/zigs.html

Luck to you :thumbup:
30 dee

57 Chevy 07-21-2006 07:29 PM

Thanks for the input.
Yes, I still have the Nova proportioning valve.

I was told that the M/C has no residual valve, but the proportioning has the proper valve for disc/drums.

I think a trip to the Chevy Parts Counter and a look at the exploded view of the M/C and P. Valve may answer a few things.

What is concerning me is the pull to either side and not consistent Although it favors the left the most.

I was thinking of backing the rears way off and see if that has any effect. A rear brake that grabs will pull the front over. ( I think)

trees 07-21-2006 07:53 PM

Residual valves are only necessary when the master cylinder is installed lower than the wheel cylinders and/or calipers. I am guessing your MC is on the fire wall. The next thing I would look at is how you have it plumbed. How many outlets does the MC have and are you you do not have them crossed ie a the ports from the large chamber going to the front and rear and the ports from the small chamber going to the front and rear? It becomes important to know which MC chamber is designed for which set of brakes (front or rear) and what the plumbing passes through, ie proportioning valve(s) and residual valves. Brakes become much simplier when you know all the variables.

Unpredictable grabbing of brakes is indicative of oil or brake fluid leaking onto the drums and the old rear end can become suspect. I would remove both rear drums and look for signs of a leaking weel cylinder and a rear axle seal. If there is, take care of it and clean your drums and shoes well and try them again. If you do not see any signs of leaks, then check your rotors for leaks. If they are good, then return to the rear and check to see if your emergency brakes are releasing evenly and smoothly. If you have the old style cables and housings and they have not been replace in your ownership of the car, they can be suspect.

Triaged 07-21-2006 11:26 PM

Is the master cylinder pushrod the right length? Are the brakes bled properly? Are there any leaks anywhere?

yesgo 07-21-2006 11:28 PM

It does sound like it could be a coincidence with changing the master. That master is also listed for some disc/drum applications BTW.

The suggestion of fluid contaminated linings sounds plausible, or even something else coincidental like a collapsing brake hose. A step by step diagnosis is in order. It would be rare that the valve body is the culprit, esp. for a pull.

Had some slight contaminated drum shoes cause an intermittant pull like that once. Left when cold, right when hot... so sometimes it would go a little left, then hard right. Most times it was fine. One side showed almost imperceptable signs of grease contamination from a bad seal... kind of a hairy build-up at the shoe ends. Maybe front discs could do something similar. Check it all.

57 Chevy 07-23-2006 06:00 PM

The system was working fine until I changed brake fluid and the M/C. As no one mentioned the "brake induced bump steer", I'm guessing that the steering box is not a suspect.

Thanks for all of the insight. I now have several paths to check out. Neither my garage or driveway are air conditioned and it's been over 100* here. We ain't use to that in Montana. I'm going to wait for a few cooler days first.


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