Power brake booster early 55, Help!!

[Sid Hiatt]

I am wanting to know if any of you have had to have your power brake booster replaced or rebuilt if you had it rebuilt who can you use in the Midwest or east coast? I've had all kinds of problem with mine and I need to do something to fix, either replace it with one Bobs Buick sells or rebuilt the one on the car, it was supposed to have been rebuilt before I bought the car . The problem with mine I cant seem to adjust it where the brake will not drag and make the brake light stay on. I have installed new brake shoes and new wheel cylinders  and new brake kits on each wheel. I take car out for short drive come back stop car no brake lite on wait a minute or so and the light comes on. I have replaced brake light switch, I've adjusted the rod to the booster like the Buick shop manual,  it is got me at my wits end and I need help.

 

SID

[old-tank]

While it is in a pressurized condition, open a bleeder on one of the wheel cylinders.  If that solves the condition, look at the residual pressure valve in the outlet of the master cylinder.  That check valve is only supposed to maintain 10-15# in the lines...not enough to overcome the brake springs or activate the brake switch.

Another problem with that system is the boot on the front of the booster needs to be vented.  If not, the brakes will apply, but not release.  Remove the boot for a test and if that fixes, then cut some holes in the bottom of the flutes.

[50jetback]

8 hours ago, Sid Hiatt said:

I am wanting to know if any of you have had to have your power brake booster replaced or rebuilt if you had it rebuilt who can you use in the Midwest or east coast? I've had all kinds of problem with mine and I need to do something to fix, either replace it with one Bobs Buick sells or rebuilt the one on the car, it was supposed to have been rebuilt before I bought the car . The problem with mine I cant seem to adjust it where the brake will not drag and make the brake light stay on. I have installed new brake shoes and new wheel cylinders  and new brake kits on each wheel. I take car out for short drive come back stop car no brake lite on wait a minute or so and the light comes on. I have replaced brake light switch, I've adjusted the rod to the booster like the Buick shop manual,  it is got me at my wits end and I need help.

 

SID

 

SID - is your problem the brakes don't work or your brake lights don't work?

[JohnD1956]

23 hours ago, Sid Hiatt said:

The problem with mine I cant seem to adjust it where the brake will not drag and make the brake light stay on.

 

Did you change the flexible hose at each front wheel and at the trans end of the torque tube?

[NTX5467]

Reason for the flexible brake line change is that, sometimes, the multi-layer construction can internally delaminate (i.e., separate) and then act as a one-way fluid valve.  It will look good on the outside, but be "apart" on the inside.  Sometimes, you can feel "soft spots" in the hose's length, but as all rubber deteriorates with age, this gets to be a maintenance issue on older vehicles.  Changing to stainless steel braided hose?  Still has rubber on the inside, so the only advantage is abrasion resistance and a possible firmer brake pedal in racing situations.  End result, no real extended durability realized in normal vehicular use.

 

In the situation you mention, there could be multiple delaminations.  One is keeping pressure on the wheel cylinder with the brake pedal released.  The other one would be the opposite, keeping pressure between the delamination and the master cylinder, keeping the pressure-switch brake light switch "on", possibly.

 

NTX5467

 

NTX5467

[Sid Hiatt]

Everything at the wheels is new hoses, springs wheel cylinders, brake shoes, so I think I can eliminate  that as part of the problem , the fellow I bought the car from told me he paid a firm in Oregon $600.00 to rebuilt the power unit and master cylinder but told after I bought the car he was not happy with results. I have bought all new stainless brake lines .I believe there is something amiss internally in the unit? There seems to be different units available to replace this old style unit , have any of replaced this unit with something else, if so what?

 

Thanks for all of feed back.  

[RiKi5156B]

I had the same issue on a 55 Century I had,rebuilt by a well known treadle vac rebuilder, failed after two weeks. Sent it back and was told some parts  had to be replaced that were worn?? What does rebuilding mean? Reinstalled and still had a problem. Leaking vacuum right out of the box. Bled according to the service manual.I thought forget it I’ll try a 7-1/2 inch double booster corvette master cylinder bought from speedway. Had to fabricate brackets and linkage got it together and took off down the road.First attempt at stopping and I sailed through the stop sign at the end of my road. What’s going on? I used this combo on a previous 37 Plymouth,worked great. Come to find out the original brake pedal ratio for power brakes on the Buick is 1.0 to 1 versus the manual brakes 6 or 7 to 1. I had parted a 55 Special with manual brakes so I put the pedal  and m/c combo in and it worked great. Hope this helps some.