58 Buick Power Brake Problem

[1958buick]

I have been experiencing a NAGGING problem with the Power brakes on my 58 Buick. For the past few months, the pedal stays at the floor and is getting harder to release as time goes on. I have great brakes, but it seems the POWER side of the operation is causing the problem. I disassembled the Moraine Power unit and rebuilt the master cylinder along with cleaning everything else involved. I've read the 58 manual for the operation of the valves and other parts, but I can't put my finger on the cause of the pedal staying at the floor. If I disconnect the vacuum line to the booster, the pedal does not stick. It appears to be an obvious issue with the power piston mechanism in the booster not releasing the vacuum or not allowing the air to transfer back thru the piston so it can return to its resting position. I've thourougly cleaned the piston wall and the leather "Piston Ring", so I know its not binding there. I'm hoping someone else may have experienced something similar and has a possible solution.

Thanks for your time... Les

[1958buick]

Sorry for the repeat, but you may have seen my previous post about this problem about two weeks ago. I thought I was updating that post with my findings after taking the unit apart.

Thanks, Les

[Dave@Moon]

If you've diassembled and cleaned the booster valves and they appear to be in working order, perhaps the problem is in the vacuum line. Have you tried replacing the line and inspecting the fitting for it on the manifold?

The line could be collapsing, or there could be a blockage acting like a check valve.

[1958buick]

Thanks for the advise Dave. It doesn't appear to be the lack of vacuum, but maybe too much or the valve is not releasing the vacuum. The piston stays forward (away from the firewall) until I either get on my hands and knees and pull the pedal away from the floor or it will release shortly after disconnecting the vacuum line going to the booster. I have had the unit in and out three times already with the hopes of it being the last, but I can't get rid of the gremlin.

[1958buick]

In case someone has this problem in the future, I am adding this as a possible solution. It recently took me about two weeks to figure out the problem with my power brakes. The pedal wasn't releasing and the unit was removed from the car numerous times trying to locate the cause. Finally I found that the "Snubber" at the end of the valve in the power piston was weak and was separating from the metal washer that its attached to. When the brakes are applied, the snubber pushes against the small reaction plate and pressure from the master cylinder pistol applies pressure in the opposite direction. This pressure was causing the snubber to expand outward and was filling an opening in the valve around the snubber which is there to channel the release of air from the vacuum chamber when the brake pedal is released. This "Cork" effect was not visible to me because it would only occur when the brakes were applied with the unit in the car and the brake line hooked up.

So two weeks of pulling my hair out was caused by a small piece of rubber approximately the size of a dime. I wasn't able to find a replacement, so I used some plumbing parts to solve the problem. I hopes this helps someone with a similar problem.

Take Care, Les

[Dave@Moon]

There are NOS rebuilding kits for these available. I just sold one this this spring on eBay.

[1958buick]

Dave,

I searched the Net and could not find a Power Booster kit. I was able to get a rebuild kit for the master cylinder from Cars, but they did not sell one for the booster. Any suggestions on where they are available, in case I have further problems in the future?

Thanks, Les

[Dave@Moon]

I bought the one I sold on eBay this year at the 2002 National in Kokomo, IN (for more than I got for it). They're not easy to find and they're usually pretty expensive. You might try the parts links on the BCA web site as well as Kanter Auto Parts every now and then to see if one comes in. Also a "parts wanted" add both here on the Buy/Sell Forum and on eBay's Want It Now service would be a good idea.

You're probably more likely to find an old NORS rebuilt unit than the kit itself. Either way you're covered.