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Sticky Brakes

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K

kcolas

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After starting the car and pulling out of the garage, I notice the brakes drag. When I step on them, they release, but then periodically "drag" again. I notice either lack of accelleration or too rapid deceleration that corrects if I step on the pedals and let them "release" again. I'm suspecting the servo, but am compiling notes and ideas. Any thoughts?

Kirby /ubbthreads/images/graemlins/confused.gif

'66 BJ8
 
Have the flexible brake hoses been replaced? Many times they get neglected during brake jobs. They can deteriorate on the inside, and still look ok on the outside. When the brakes are applied, brake fluid is forced through the flexible hoses into the calipers (front) and cylinders (rear) and the brakes are activated. But when the brake pedal is released, the old brake hoses collapse and the brake fluid does not return to the master cylinder, but is trapped causing the the brakes not to fully release. Other causes could be an out of round front brake disk, perhaps wrapped from over heating or bad (weak) return springs in the rear. When you release the brakes, does the car pull to one side? That might indicate where the problem is, but if it's hoses, replace all three.
 
The lines don't have much wear on them, but replacing them is probably a good idea. The problem is that the car applies the brakes itself when the engine starts or accellerates (increasing vacuum.) The pedal applies the brakes and releases them fine. Pedal is firm, brakes apply and release evenly--no pulls, etc.

Kirby
 
More info:
From outside the car(off) I can push it forward. When I start it, the brakes lock up. If I step on the pedal, they will release. If I turn off the car, they release. Seems like the servo ( I plugged the vacuum line and the brakes worked, albeit very tough compared to servo ops). COuld this be the master not completely returning and signalling the servo to "work"?. I'm not familiar enough with the workings of the system to tell. Anyone see this before??

Kirby
/ubbthreads/images/graemlins/frown.gif
 
Kirby , I think you have a bad vac valve in the booster.--FWIW---Keoke
 
I had a similar problem with my Jeep Wrangler. The front disc brakes would not release, acceleration was severly retarded and rapid deceleration occured. I could tell it was the front brakes because they got very hot after driving a while. Of course the Healy doesn't have a dual master cylinder, so all wheels could be effected. Replacing the master cylinder solved the problem.
 
David Nock suggested checking that the master fully returns, so when I can figure out how to do this, I think I'll have the problem isolated to the culprit of the two components. Then I'll replace the flex hoses as well when the system is open. Thanks for the help so far. I'm leary of doing the brake work since its been a while since I tackled brakes. Armed with Bentleys, Tech Talk, and this forum helps.
Thanks for the replies
Kirby
 
I thought I'd report on (hopefully) closure of my problem with the brakes. I had the booster rebuilt because of the random brake application when the car started and lack of confidence in the individual that rebuilt it last time. In the course of the project I replaced the flex lines in front--the brakes that would randomly not release, also. In fact , years ago , I had a wheel smoking after a drive and had to replace the wheel bearings., The shop rebuilt the brake, but not the lines. I also had the resevoir powder coated on assurance from the Nocks' shop that solder was not a problem. Used a gasket in the lid, and new rubber washers under the clutch tube. No leaks so far. The brakes work great, good pedal resonse, and no sticking. Re bleed of the clutch next....
 
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