Brake Problem

Jim Johnston

Jim Johnston

Senior Member
A friend has a '31 Model A equipped with 'early V8' hydraulic brakes. The right front brake will lock up if you really 'jump' on the pedal. If you apply the brakes gently you still feel some bias toward the right front but the stop will be straight. The right front drum always measures a higher temperature than the left front (infra-red thermometer). Here's what I've done so far-

First pass - inspected drums and linings, all OK. Adjusted and bled brakes.

Second pass - replaced wheel cylinders, shoe return springs, adjusted and bled brakes.

Third pass - Removed shoes; cleaned backing plates: lubed all hard contact points; 'scuffed' shoes and drums with medium emory cloth. reassembled, adjusted and bled brakes.

I sure would appreciate any thought or comments on what to do next. THANKS.
 
Is there a chamfer on the leading and trailing edges of the shoes?? Have the drums been turned/cleaned up AND shoes "arced" to the drums??
Paul in CT
 
Paul, The shoes are chamfered. Forgot to mention that all of the work listed applies to both left and right front. I do not know the history of the brake installation, only that this problem has existed for some time now.
 
check or change the left brake hose.you can test it by jacking up the front of the car and spinning the front wheels they should turn freely. Next have someone step on the brake pedal as you turn the wheels,they should stop at the same time if the left one doesn't the problem is in the hose or the hard line fitting. i hope this help good luck
 
Since someone in the past "transplanted" the hydraulic brakes to the Model A, be sure the wheel cylinders are the same size. It's a long shot but it could be. Good luck!
 
Jim Johnston said:
A friend has a '31 Model A equipped with 'early V8' hydraulic brakes. The right front brake will lock up if you really 'jump' on the pedal. If you apply the brakes gently you still feel some bias toward the right front but the stop will be straight. The right front drum always measures a higher temperature than the left front (infra-red thermometer). Here's what I've done so far-

First pass - inspected drums and linings, all OK. Adjusted and bled brakes.

Second pass - replaced wheel cylinders, shoe return springs, adjusted and bled brakes.

Third pass - Removed shoes; cleaned backing plates: lubed all hard contact points; 'scuffed' shoes and drums with medium emory cloth. reassembled, adjusted and bled brakes.

I sure would appreciate any thought or comments on what to do next. THANKS.
Click to expand...

I see you have replaced the cylinders so they should be the same size. I don't see where the linings were changed. Linings contaminated with grease or brake fluid will get softer and grab. I would changes sides with the drums. If that doesn't move the problem to the other side I think I would consider changing the linings.
 
Convert back to the original mechanical brakes ---much less problems --

Swap 1 shoe from each side.

When you say 1 side runs warmer --is that even when not using brakes??

After dealing with this problem on a 39 every year or so (leaks, moving shoes around, the pulling from contaminated linings, grabbing)I would have kept it if it was easy to make it mechanical brakes ----I kept the 36 because it has mechanical brakes.The mechanical brakes on my A have been trouble free for 40 years, just minor adjustments.

Do both sides linings look the same color?
Is the wear pattern the same, and the contact area the length of the lining (the centering pins at the bottom properly adjusted??)

Lining that has had fluid contamination cleaned off doesn't have the same friction as good lining.---no matter how much you clean it

with both drums removed have someone push the pedal gently --you don't want it pushed too much to pop out the pistons, compare the operation of each side ---the pedal pressure to start the first motion ---then watch how they return

How close to the same size are the drums?

When you bleed the brakes does the stream out the bleeder seem the same?
 
I just did a '40 Buick this year that had 0ne front and the single rear hose plugged.
It's not uncommon to find a hose jammed up with it's own material
 
I had the same problem on my 49, it would pull drastically to the right on a hard stop. I replaced both rubber brake hoses and it solved the problem.
 
Thanks for all the input.

chevy man 1 & Paul/Woodinville - during the 'third pass' I did remove the left brake line. All of the lines from the hard lines to backing plates are Russell steel braided lines. I flushed the line with alcohol and didn't see anything obvious. I also disassembled the banjo fitting at the 'hard' line and did not find anything.

40cpe & aaron griffey - I guess I'll try swapping the shoes next - Thanks.

Kurt in NJ - The temperature differential at the drums is only after using the brakes. I agree with you on the mechanical brakes. My '30 Tudor with mechanical brakes stops every bit as good as my '40 Fordor. My friend purchased the car I'm working on with the hydraulics already installed.
 
The brakeshoes has a bushing in the bottom, if its sized to the brakeshoe it can make it harder to move.

Switch brakedrums to.
If they are thin they can cause problems.

maybe some pics can make it easier to see the problem.

Had a similar problem with discbrakes long time ago, somewhere over the time one set of discpads had been swapped out for another manufacturer, causing the difference between right and left. And you only worked on one side at the time..
 
When the shoes were installed were they properly centered? There are two proceedures that need to be done when new shoes, or very worn shoes, need adjusting. The cenetring adjustment must be done first. It's not hard to do, but requires two people to do it. Hard for me to explain. A consult with a service manual should explain it. Also, what kind of lining is on the shoes? The earliest Ford hydraulic brakes used woven lining. The woven lining available now does not always get along well with cast iron drums. I have one wheel on my A that gives mea lot of trouble until the drum and lining get warmed up good. Grabs, chatters, squeaks and squawks for no good reason. It's enough to drive me nuts. :eek:
 
You must log in or register to reply here.
Back
Top