1955 Bleeding Brakes

[pauljacobs]

Hi - I'm having a difficult time bleeding the brakes on my 55. It still has drums all the way around (I have the disk kit but haven't installed it yet). No matter how much fluid I run through the brakes remain soft and don't feel reliable. Any advice?

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[fordrodsteven]

Hi - I'm having a difficult time bleeding the brakes on my 55. It still has drums all the way around (I have the disk kit but haven't installed it yet). No matter how much fluid I run through the brakes remain soft and don't feel reliable. Any advice?

I you've properly bled the brakes and there is no air in the lines it should be a good hard pedal. Is everything else up to snuff? (brake shoes not oil soaked? Good hoses that are not expanding/contracting as you apply brake pressure?) If those brake shoes and hoses are assuredly good I would look to the master cylinder as the problem. The reason I say that is because if you have a bad wheel cylinder (leaking) you would see fluid leaking onto the shoes and dripping from the brakes. If the master cylinder has bad seals and is leaking it could be leaking internally.Basically just allowing fluid to pass from one side of the piston to the other side and you would not see any fluid leak out. That would definitely cause the pedal to feel "squishy". When you install the disc kit are you going to install a dual master cylinder? You could change out the master cylinder first then insure the brakes feel good. After feeling comfortable with the drum brakes you could then finish the disc brake conversion.

 

[64ZCODE]

I had a situation where the master was leaking into the booster. Along with having 4-5” of brake fluid in the booster, the brakes were squishy.

 

[fordrodsteven]

Speaking of boosters. If your 1955 has power brakes you could have a bad diapragm in the vacuum assist booster that is bolted on the frame. If the diaphragm is bad you again would not see leaking fluid because the vacuum would suck it into the engine and burn it off when running. If you have power brakes you can disconnect the vacuum hose at the booster to see if it is all wet with brake fluid. It shouldn't be. If you do not have power brakes you might find that the master is leaking a little out the back. Evidence of leaking out the back of the master would be weeping fluid running down the firewall in the engine compartment or leaking down the firewall on the interior side and possibly causing wet carpet.

 

[64ZCODE]

Plus level of fluid in master reservoir dropping without corresponding leakage from lines or wheel cylinders.

 

[JDJ]

Speaking of brake booster. ..Has anyone got a source I can go to to review,read, to restore the booster?

 

[JDJ]

Regarding the master cylinder...can I ,or is it better to put a dual master cylinder on my 55 Thunderbird? I’ve also decided to keep all four wheels drum and shoes.

 

[64ZCODE]

The ‘55 has separate brake lines front and back, right? Then dual master gives you added safety in event one circuit fails. But, single master systems do stop the car.

 

[fordrodsteven]

To put in a dual master you would have to do some replumbing of brake lines. If your going to stay with drums all around not much else required. If you convert over to discs you would have to also install a proportioning valve.

Regarding the booster; I would have to do a little research on your rebuild question. I'm pretty sure you can buy the required parts for a rebuild from many of the Thunderbird suppliers. (Hills, NPD, Prestige, Concours Prts, Larry's).

update; NPD has a kit for booster repair (T-2309-1) at a cost of $175 Hill's lists a booster rebuild kit for $110 (2005K)
Concours Parts lists a rebuild kit but no price.
Obsolete parts lists a replacement booster assembly for $450

 

[64ZCODE]

Steven, could he eliminate the booster as the cause by disconnecting the vacuum? Then it would not affect pedal travel, right?

Doug

 

[fordrodsteven]

Steven, could he eliminate the booster as the cause by disconnecting the vacuum? Then it would not affect pedal travel, right?

Doug

Pedal travel? I don't think booster attached or disconnected would have any affect on pedal travel. The pedal would get much harder to apply brakes. (as in manual versus power brakes).
Actually on my '55 , when I bought it, the booster was disconnected and it worked just like manual brakes.
I would pull the vacuum line off the booster and step on the brake pedal. If fluid comes out the booster it has a bad diaphragm. If fluid does not come out the booster then the diaphragm is probably okay.
His original complaint is about a squishy pedal. That means something is "gving" in the system. He could have a leak somewhere but didn't say he saw any leaks. The cause of the squishy pedal could be a bad hose but I'm thinking most likely it's the Master cylinder.
New master cylinder from Hill's is $80. NPD has a new master for $109. rebuild kit $30.
Obsolete Classic Auto Parts lists new master for $80 and rebuild kit for $16

 

[Ward 57]

I agree with the above. The seal on the master cylinder may be holding so you don't see a leak but the gasket on the plunger is leaking and the brake fluid is bypassing. rebuild kits are available for under $30. An easy but time consuming project as you have to bleed the brakes again. Oh I almost forgot.. It's been over 30 years since I did that, But if you have power brakes yo only need to bleed to the booster as there should be a bleeder valve on there.