56 Cadillac brake pedal problem

[Armond]

On my 56 Cad. once the engine is running if I press on the break and release the pedal, it returns back up very quickly. However, when I turn off the engine the brake pedal stays down and the brake lights stay on and  I always use my foot to lift the pedal up. Is this normal or something is not operating properly. Any ideas? Thank you for you suggesstions.

[Dave Shepherd]

Not normal, I would say there may be an issue with the booster.

[Otto Skorzeny]

Check your vacuum reserve canister for leaks and the hose that connects it to the booster.

Howdo the brakes work, otherwise?

[J. Gomez]

On my 56 Cad. once the engine is running if I press on the break and release the pedal, it returns back up very quickly. However, when I turn off the engine the brake pedal stays down and the brake lights stay on and  I always use my foot to lift the pedal up. Is this normal or something is not operating properly. Any ideas? Thank you for you suggesstions.

Armond,

A few other possibilities could be broken piston return spring, misaligned pedal to unit rods, or other faulty booster components. Your brief description points to a possible booster problem either for the Bendix or Moraine unit. If there are no restrictions and/or binding the piston return spring should return the pedal back to its original position.

Good luck..!

[Armond]

I would like to thank everyone in trying to help me with my situation. During the normal driving times the brakes work fine. All the hoses are new and the booster pump was rebuilt about a year ago. I have checked the springs and rods are free and I lubricated them too. It seems that everything is pointing towards the vacuum booster or canister, I will check them this weekend. Thank you

[Christopher Petti]

I would like to thank everyone in trying to help me with my situation. During the normal driving times the brakes work fine. All the hoses are new and the booster pump was rebuilt about a year ago. I have checked the springs and rods are free and I lubricated them too. It seems that everything is pointing towards the vacuum booster or canister, I will check them this weekend. Thank you

Armond,
  I'm having the same issue with my brake pedal. Mine is stiff when the car is off and sometimes when I'm driving but after a while it will not return fully and I have to lift it up with my foot. What did you find? I was thinking of changing the vacuum hose between the canister and the booster.

[John Washburn CLC 1067 Sadly deceased.]

Not sure this will help, but there is a rod adjustment from the rod that comes from the vacuum canister, then goes to the petal, this is critical. If it is not adjusted correctly it "might" cause the problem you are encountering.

The 56 was unique, in that the master cylinder had no real piston, it was more of a floating, vacuum assited unit. So it works much differently than earlier and later models.

The 56 had a few design flaws, the steerring gear, the vacuum brake unit are two that drive me nuts.

[J. Gomez]

Armond,
  I'm having the same issue with my brake pedal. Mine is stiff when the car is off and sometimes when I'm driving but after a while it will not return fully and I have to lift it up with my foot. What did you find? I was thinking of changing the vacuum hose between the canister and the booster.

Christopher,

One small word of caution, if you are replacing the hose between the canister and the booster or from the intake manifold to the booster make sure it is designed for pressure, the regular heater/fuel type hose are a big no, no as they will collapse and you will have no vacuum or reserve from the canister ..!

I personally think original boosters could be brought back to working condition with just minor maintenance without a major rebuild, unless of course the unit is totally gone. The first item is the rear piston plate wick is well lubricated this would keep the leather packing properly condition. Second clean and lubricate the vacuum cylinder inside wall. These minor steps should extend the life of the leather packing.
I do not recall seeing any preventing maintenance details for the booster in the manual, just an afterthought..!

[Armond]

Christopher,
What I found was a rusty and deteriorated canister bottom that can not hold the proper vacuum. It seems like I have found the problem, but I did not get a chance to fix it to be sure.

[Christopher Petti]

Armond and Jose,
  I am finally addressing this issue right now because the brake booster is out of the car and I am waiting for parts in the mail. I my take out the vacuum canister from the inner fender. See if I can find some leaks and patch them. It's definitely getting a new pressure hose that is made for this application. The one that runs between the canister and the booster. I'll also check the linkage from the pedal to the booster ans see if everything is properly assembled.

Thanks guys!