C2 Sticky Situation (Brakes)

[Bruce Boatner]

I recently replaced the master cylinder on my 1964 with factory power brakes. The brakes work MUCH better now (will throw you through the windshield if you aren't careful) but there appears to be unwanted pressure in the brake system when the car is fully stopped. I have an auto transmission and the car will usually stay still and not "creep" forward when I completely remove my foot from the brake pedal. Everything seems normal when the car is coasting, but the "stickiness" reappears after the brakes are applied again.

I do not think any type of adjustment can be made and imagine that the problem may lie with the master cylinder. I was hoping that the problem would go away with time/use but the part-time "hill holder" feature is starting to get on my nerves.

Any advice and counsel would be appreciated.

[Brian M.]

Re: C2 Sticky Situation (Brakes)

Have you replaced the soft lines? If not the could be restricted on the inside and holding pressure.

[Bruce Boatner]

Re: C2 Sticky Situation (Brakes)

I have not replaced the soft lines but probably not a bad idea to do so in any event. I do think the lines are the problem in this case because I drive the car all the time and the sticking occured immediately after I replaced the master cylinder.

[Bruce Boatner]

Re: C2 Sticky Situation (Brakes)

Correction--I do NOT think the lines are the problem

[Michael H.]

Re: C2 Sticky Situation (Brakes)

Bruce,

When you installed the PB unit, did you make sure that you had at least 1/8" of free pedal movement? Sounds like something isn't allowing the pedal/cyl to fully return to it's starting point.

[ken edmunds]

Re: C2 Sticky Situation (Brakes)

I had the same issue with my 66 coupe-when I installed the booster I had adjusted the rod too long and when I applied the bralkes, the pedal stuck to the floor. I just shortened the rod by 1/4 inch increments until it worked ok.

[Bruce Boatner]

Re: C2 Sticky Situation (Brakes)

Mike,

I only replaced the master cylinder and left the booster alone. With the old master cylinder I really had to put a lot of pressure on the brake pedal to keep the car from creeping forward at a stop (put the excitement back into sitting at a light)

I bought the new/replacement master cylinder from the local auto parts store, but it looks exactly like the original except for an extra bleeder. I'm thinking the new master could have been built too tight, but I have never experienced this or heard about this happening before with other master cylinders. Could also be that the hole in the replacement m/c piston is shallower than the hole in the original piston (hole that receives the rod from the booster) but I did not notice a difference when I compared the two prior to installation.

I guess I could bite the bullet and have the original m/c sleeved and rebuilt, but I would prefer to let a future and more anal owner deal with this. Not a huge deal as the car stops well, but it's just bugging me. You know how it is!

[ken magrene #44841]

Re: C2 Sticky Situation (Brakes)

i fixed a 64 at my shop with the same problem - rod was too long - had to replace??

[Frank C.]

Re: C2 Sticky Situation (Brakes)

Bruce....I don't see how you could have a pinched brake line or other restriction if all you did was replace the MC. I would definitely replace all the brake lines if they have never been replaced before and also the brake return springs. One of my little quirks on a car I don't know any history of is to put both feet on the brake pedal and let 'er rip. You'd be surprised what can happen, but better in the driveway than on the freeway. Good Luck Frank

[Brian K.]

Re: C2 Sticky Situation (Brakes)

Had this problem with my 66. Not a freeplay issue. New master & no problem.

[John DeSalvo]

Re: C2 Sticky Situation (Brakes)

I'm new to Corvettes, but not to classics. Did you check to see if there is a residual valve in the master? I know that drum brakes need them, but you might have one in the line and now with the new master you might have another in the M/C. They also come in different pressures, maybe you could switch the one you have in the M/C for a 5 lb. one if it has a 10 lb. one now.