My 69 SS has always had a problem locking up one of the rear wheels. Some parts of the brake system were carried over from before to after the restoration. Both the calipers and the rear wheel cylinders were carried over parts. They were installed back in 1998 or 9 and even back then it had a tendency to lock the rear wheels up in a hard stop. I thought it was the proportioning valve causing the issue. Which rebuilding it did help a lot, but the symptom isn’t fixed completely…yet. I am wondering if there are different bore sizes for the rear wheel cylinders? Perhaps one of my wheel cylinders has a larger bore causing that wheel to lock up. I could take the wheel cylinders off the verify and order parts. But, if they are correct, perhaps there is a vehicle that takes the same design wheel cylinder, just with a smaller bore?
Last week I found the right rear wheel cylinder leaking. The brake shoes were staturated. I replaced both rear wheel cylinders. Bled the rear brakes. Drove to the gas station and it still wants to lock up the right rear wheel. I took the wheel and drum off then cleaned the shoes with brake clean. I’m hoping the locking-up with subside. Realistically, spraying brake clean on it isn’t going to fix the problem. Either way, I am running out of ideas on why the right rear keeps locking up. The proportioning valve was rebuilt a within a couple years ago. That made a big difference. But, didn’t stop the problem. Maybe this week I’ll throw some new shoes in it.
While write this, I was wondering if I am looking at the wrong end. It seems weak front calipers, or weak pressure to the calipers could cause a symptom like this. Hmmm. I don’t have time to fiddle-f**k around with a brake problem. I’d much rather have a transmission problem.
As I go over the chain of events. I am realizing that it could possibly be my front calipers. When I do step on the brake and the rear locks up, I can step on the pedal pretty hard and the car doesn’t slow down any faster. Seems possible that the calipers might not be traveling as far as they should.
Hmm, was going to an event with the car tomorrow. Maybe I’ll take something else.
My 70 acts the same way. When I step on the brake quickly, the right rear wants to lock up first. I haven’t had it apart recently, but its time for a tear down for inspection!
Today, I did drive the car to the Brockway Truck National Show in Cortland, NY. Which is about 4 hours from my house. For the most of the trip I anticipated stops and coasted down with braking lightly. There were a few times I stepped on the brakes moderate to hard and it was o-k. I think it still needs adjustment or correction somewhere in the system. The first course of action will probably be to take the calipers off and see how well they move and how far they extend. Hopefully to correct the problem I won’t have to pull the proportioning valve or master.
I agree that you should replace the shoes rather than rely on the old cleaned up with brake clean. Otherwise I think you are on the right track checking the calipers, etc.
Bummer, that would have been cool. Not sure if I would have been able to make it as I left the show a little early to get home before it was too late. Never enough hours in a day.
