Brake Shoes Won't Fully Expand When Rods Attached

J

jerml2

Junior Member
Bought our first Model A a few weeks ago.

For the front brakes, I've taken apart the brake assembly completely, cleaned everything, and replaced the rollers. I've got 15 degree forward lean on the brake arms per Les/red book (with no slack). When I push the brake arm backward to engage the brakes by hand (rod not yet attached), the wedge goes down nicely and spreads the shoes. And the brake arm is at 90 degrees when the wedge is fully down.

But, when I connect the brake rod and press the brakes, the brake arm comes fairly short of 90 degrees, as such the wedge hardly travels downward and the shoes hardly move. The brake pedal travel is about halfway to the floor; I believe that's normal given the brake adjustment tool/direction in the red book.

Any thoughts? Thanks!
 
You must have the drums on to properly adjust the brakes, and the shoes must be properly arched to the drums. Then adjust the wedge so that you expand the top or the shoes. The smallest amount of travel of the adjusting wedge should begin to engage the brakes. Sounds like you have too much travel in the front brakes, and the adjustment of the rear brakes may be limiting brake pedal travel.
 
Two things to look at are:

1) Are the rods adjusted correctly

2) Are the actuating rods the correct length? Do you need to add the little pills at the bottom of the rod?

3) Are the roller tracks in good shape?

And Welcome to the Barn.

Mike
 
Maybe not related, but I will comment.

Are you using new wedges or used ones that look good with some wear on them?
The wedges do not wear evenly and the brakes, like most of the A, are precision manufactured. Used parts are often made pretty with a file which changes the wedge profile. For a profile measured in thousand of an inch it is easy to take a lot off.

What about the operating rods, are they new or are the ball sockets worn?
Are the rods worn used?

Then have you matched the shoe diameter to the drums for 100% contact? Have you centered them?

If you do not have the special tools needed to do the above properly and you really want good brakes here is a place where you are better off paying someone to do it properly.

Anyway stuff to consider.
 
nkaminar said:
Check the things that others have indicated but also check the rod that goes from the brake to the cross shaft. If this is too short the levers on cross shaft will hit and keep the brakes from fully activating. I found this on a car I worked on. I had to get a new rod, https://www.snydersantiqueauto.com/product.htm?pid=977597&cat=41655. The mushroom shaped stop at the back of the rod must hit the frame cross member.
Click to expand...
Thank you for your reply to my post on the brakes! I checked the pedal to cross shaft rod and the mushroom is against the frame. Does this mean I have the right size?

What did you mean by if too short the levers on cross shaft will hit and keep the brakes from fully activating? Could you expand on that?

I greatly appreciate your help! This is a bit frustrating.

Jeremy
 
Adjusting the brake shoes and adjusting the rods are two different things.
Adding pills (if needed) is messy, but not all that hard, that will adjust your brake shoes
After the brake shoes are adjusted move on to the rods (replace rods/turn buckles if needed)
Then you can do the final adjustment on all four (do you have a brake adjusting board?)

You can arc the brake shoes by hand if need be, that too is messy and takes some time (seems no one has/uses arcing machines anymore)
 
Sorry for the low res. They don't have to expand much
 

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If the stop is hitting the cross member of the frame then you are OK with the length of that rod. With the car I was helping with the levers on the cross shaft were hitting the running board bracket. We found it by me climbing under the car while the owner was pressing on the brake. With the right length rod you are probably OK but check for interference there and other places. If nothing is stopping the mechanism from operating correctly then you probably need one or more shims: https://www.snydersantiqueauto.com/product.htm?pid=977561&cat=41655. With the rods disconnected the lever should only move a few degrees from the 15 degree position before the brake starts to grab. I cannot remember if you said you adjusted the brakes but if you are moving more than a few degrees then you need the shims or you need to screw in the adjuster more. This is assuming that all the other parts are 100%.

The lengths of the brake rods should be adjusted for the correct angles at the levers and then not changed again.
 
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The rod that attaches to the brake pedal - the other end of that, does it hit anything? Have someone jump in and push the pedal down while you are under the car with a flashlight.

When these things happen it is usually something simple.
 
Thanks! I have adjusted with shims. I needed to add one to the left side. And I then adjusted the clevis to align with the brake adjuster arm at 15 degrees. I feel fairly confident that I’ve got the brakes themselves set up correctly.

Someone else brought up a good point about the arms at the cross shaft being vertical. I checked that and they are close but maybe slightly off. I’m guessing a few degrees there wouldn’t be enough to stop the rod from pulling the brake arm to 90 degrees would it?

Thanks!
 
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jerml2 said:
Downloaded this on my computer and I honestly can't read the text/numbers. Could you let me know what the take away is? Thanks!!
Click to expand...


Take away is the shoes only have to expand a very small amount to go from no contact to full contact.
 
Back to what someone else suggested ........... You can’t adjust the brakes correctly without the drums mounted. Your text suggests that you are viewing the movement of the wedge and shoes ......... which means that at least the front drums are off the car. And, it sounds like you are expecting that the wedge will be pushed all the way down to spread the shoes and stop the car.

In actuality, as someone else stated, with brake rods adjusted properly and adjusters on the backing plate adjusted properly, the brake levers will have to move very little from the 15 degree position and the wedges inside the backing plate will be nowhere near fully extended to stop the car. And, on newly rebuilt and adjusted systems with new cast iron drums and all other parts as close to spec as possible, the brake pedal should certainly start to affect braking before being half way down.

It sounds like you’ve got the adjustment of the rods and the levers done pretty well. Many folks do not understand that the 15 degree mark is “when the slack is removed”. You are fully aware of the slack needing to be out of the lever travel as you noted in parentheses. Bravo !! Now, go back and re-read how Mr Andrews says to set up the adjustments at the backing plates. Sounds like you’re on your way to success but got derailed by over analyzing the inner workings behind the drums.

Good luck. Bob Bader
 
The cross shaft gets a lot of wear also ,you may want to check that out,There’s repair kits and rebuild cross shaft available it’s the “heart “of the mechanical brake system, also how well do the brake and clutch pedals fit on the shaft? Play in the system builds up.
 
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