1953 Buick Roadmaster Brake Trouble, Need HELP

[FireballV8]

Hi everyone
I have a 53 Roadmaster with power brakes that are very sensative, if you apply the brake in a normal fashion it will stop right away and lock the wheels. If the pedal is depressed very slightly the car will slowly stop.

Has anyone had this issue before? Is there an adjustment in the linkage or brake booster?

Thanks
Steve

Email: steveclassic@earthlink.net

[1953mack]

Do you have the original 1953 troublesome Kelsey-Hayes Model 6 C-100 power brake cylinder or the one that replaced them, during the "campaign" (recall), the Delco-Moraine unit that was used with the 1954 Buick power brake system?


Al Mack
"500 Miles West of Flint"

[Pete Phillips]

Steve,
I haven't worked on '53 power brakes, but on the manual brakes and on the '55 power brakes, there is a threaded stirrup just in front of the master cylinder, that can be adjusted forward or backward, to increase or decrease the amount of travel of the linkage.
Are you sure you don't have two wheel cylinders locking up or a partly blocked brake hose?
Pete Phillips, BCA #7338

[martylum]

V-8-I too am restoring a 53 Roadmaster but have not gotten into reassembly yet. I did read over the power brake section today and did not find any reference to too sensitive power boost in the brake troubleshooting section so it must not have been much of a problem when the cars were new.
The section did state the pedal travel is very short and that the pedal in a rest position should be very close to the level of the gas pedal. Could it be your brake pedal and linkage adjustment to the master cylinder is not properly adjusted? Might be a good idea to read this section of the shop manual very carefully. If you've just installed new lined shoes it might be the adjustment of the shoes to the drums is not properly set up. Too much travel of the shoes before contact with the drums can cause grabbing as can improperly instaled shoes.
Martin Lum
53 76 X Roadmaster

[FireballV8]

Hi Al
It looks like the original unit, do you know what the Moraine one looked like?
Thx
Steve

[1953mack]

The easiest way to visually determine which Power Brake Cylinder (PBC) you might have is to look at the hydraulic brake master cylinder attached to the rear of, what I like to call, the "Atmospheric Air-Piston-Vacuum Can". The Kelsey-Hayes hydraulic brake master cylinder unit is round, whereas, the Delco-Moraine Unit is tapered.

My thinking is that you may have a vacuum related issue and not a mechanical adjustment to the pedal push rod issue. Usually with this system, the harder the brake pedal is, the more vacuum is required. When sufficient vacuum exists in the PBC, the pressure needed to apply the brakes is provided by the PBC instead of foot pressure applied to the brake pedal.

1953 was the first year for Buick power brakes and they had problems leading to a recall. One of the issues was loss of vacuum when the engine was shut down or when the engine stalled out (picture yourself driving down a mountain road ). Once the engine stalled, the book says you might have two pushes on the pedal left before the pedal gets harder to depress, harder than the pedal pressure on a regular foot powered hydraulic brake setup.

To address this issue, cars produced after October 1, 1953 had an electrical powered Power Brake Vacuum Pump installed. Before this, vacuum tapped from the intake manifold, was a direct line to the power brake cylinder. The vacuum pump was installed between the intake manifold supply and the power brake cylinder, on the sloped rear portion of the driver's side inner front fender, and wired so that the pump kicked in when the ignition switch was turned on, or when the engine rpm's fell below 250; and, automatically turned off when the engine rpm's reached 450. Do you have this electric vacuum pump and relay in your power brake system?

Buick also came out with parts to update the Kelsey-Hayes unit that addressed the reaction piston, cups, seals, and O-rings. The recall replaced the Kelsey-Hayes Power Brake Cylinder with a Delco-Moraine labeled unit. This Delco-Moraine unit was used on 1954 and some later Buicks.

Steve, send me an email and I can fill you in on any further questions you might have and copies of Product Service Bulletins that addressed this problem in further detail.

Al Mack
"500 Miles West of Flint"
al@ajmack.com

[martylum]

Hi Al-your comments are of much interest as I'm restoring a 53 Roadmaster with power brakes. I did not find an electric powered booster pump during disassembly and will check the unit on the car against the shop manual to see if it 's the original booster-master. If so, what do you recommend doing when restoring the power brake system?

In 1971 I bought a new Chevy Impala, a very large car, and had the engine stall at the head of my 150 foot driveway. The driveway in a 10% grade and I had a heck of a time stopping the car before reaching my garage door-both feet barely gave me some stopping. I think I completely forgot about the foot operated emergency brake.

Did the Delco-Moraine unit make for easier stopping if the engine stalled?

Guess this potential situation calls for a very good functioning emergency brake.


Martin Lum
76X Roadmaster

[1953mack]

Hi Al-your comments are of much interest as I'm restoring a 53 Roadmaster with power brakes. I did not find an electric powered booster pump during disassembly and will check the unit on the car against the shop manual to see if it 's the original booster-master. If so, what do you recommend doing when restoring the power brake system?

In 1971 I bought a new Chevy Impala, a very large car, and had the engine stall at the head of my 150 foot driveway. The driveway in a 10% grade and I had a heck of a time stopping the car before reaching my garage door-both feet barely gave me some stopping. I think I completely forgot about the foot operated emergency brake.

Did the Delco-Moraine unit make for easier stopping if the engine stalled?

Guess this potential situation calls for a very good functioning emergency brake.



Martin Lum
76X Roadmaster

#1. Try to find a rebuildable Delco-Moraine Power Brake Cylinder and an electric powered vacuum pump with mounting strap and relay. You won't find any info on these parts in a 1953 Buick Shop Manual. The 1953 Shop Manual was published before the first 1953 BUICK PRODUCT SERVICE (BPS) BULLETIN came out on January 31, 1953.....the vacuum pump came out in October 1953. The updated parts were explained in the 1954 BUICK SHOP MANUAL and the BPS BULLETINS for 1953 and 1954.

#2. No. The vacuum pump supplied the vacuum when the engine stalled. The Delco-Moraine unit addressed another problem the Kelsey Hayes unit had: the seal between the hydraulic brake cylinder and the Power Brake Cylinder "Atmospheric air - Piston - Vacuum Can". Complaints of brake fluid being sucked out of the hydraulic brake cylinder was supposedly corrected by updating the Reaction Piston Assembly, O-ring, and spring.


Al Mack
"500 Miles West of Flint"

[buickconvert53]

This is on my '53 Roadmaster and I belive it to be the original Kelsey-Hayes unit.

[1953mack]

This is on my '53 Roadmaster and I belive it to be the original Kelsey-Hayes unit.

Negative. It's a Delco-Moraine unit, identifiable by the tapered brake cylinder at the rear (left in picture) and the different shape of the front head (right in picture) than the original Kelsey-Hayes unit. Look for some type of MORVAC name stamped on the unit.

This could be a car that was updated when the "campaign" was announced. It would be interesting to know if the crossmember was reworked (butchered?) to mount this Power Brake Cylinder.


Al Mack
"Too many miles from the North Pole"

o< : o )

[JohnD1956]

Looks like the power brake pushrod pictured in post #9 has that threadded stirrup Pete mentioned above in Post #3. But it does not look like something that all of a sudden goes out of adjustment.

[FireballV8]

Hi Guys
Still have not figured this out, last night my mechanic neighbor friend came over and we messed with it more readjusted the brakes and drove around, a bit better but not good to drive. We took the vacuum line off of the booster and still had the same issue, but with a very hard pedal as Al mentioned above. So this may not be booster related. Can the shoes be damadged to cause this grab effect? Any other ideas?
Thanks
Steve

[old-tank]

Steve
Pull the drums and be sure there is no oil, grease or brake fluid on the shoes. Also check the contact pattern. If the drums were turned be sure that the shop polished out any spiral grooves from the lathe. The shoe friction material may be too soft to make it grabby --- I had the opposite problem with Raybestos shoes.
Willie

[bhambulldog]

could it be that the shoes need breaking in? Perhaps, the shoes are not concentric with the drums? Maybe, some hard braking in a safe place (large empty parking lot)?