The Stovebolt Site Forums The Shop Area Driveline Brake shoe wear

No, not talking fashion here. I was looking at the rear brakes and the leading shoe has about .20 and the trailing shoes have about .30. Both sides similar. Is this normal or should they pretty much wear the same. This is a Ferd if that makes any difference.

Dennis

If the brakes you have are "self energizing" the primary shoe is normally thinner than the secondary shoe. The front shoe pushes the rear shoe into the drum and putting more pressure on that shoe. In theory, by the time the shoes are worn out, they will be about the same thickness.

Joe

Thanks Joe. What does self energizing mean?

Dennis

If I remember there is an anchor pin/post at the top of the backing plate where the tops of both brakes shoes rest against.

With the brake adjuster between the rear and front shoe.

The front shoe contacts the brake drum which causes the front shoe to move with the drum.

The front shoe then pushes the adjuster in the same direction which then pushes the rear shoe in the same direction which causes the rear shoe to press against the anchor pin and up against the drum.

The energy from the primary (front) shoe caused the secondary (rear) shoe to press against the drum. Self energizing.

Hope my memory is not wrong.

What year and size truck?

Thanks for that explanation 32vid. Tim, this is on my 1/2 ton '40 Chev but I'm running a Currie F... 9" with '80s 11" F... drums. I could post a picture tomorrow. Just sprayed some primer so garage is on the EPA list for the night.

Dennis

The Bendix type brake with the top pivot pin and the floating adjuster at the bottom has a tendency to wear the rear lining faster than the front. The forward rotation of the drum torques the shoe assembly toward the rear and applies more force to the rear shoe. That's also why the shoe with the longer lining material is always installed at the rear. Manufacturers install thicker lining on the rear shoe so both linings wear out at about the same time.

Huck brakes used to wear out one shoe almost entirely, and the other shoe on the same wheel would have little to no wear. Flat rate mechanics would try to replace only the worn shoe, hide the other one, and after a few brake jobs they had enough new brake parts to do a shade tree job at home. Since both shoes were identical, swapping only the worn one was possible.
Jerry

Here's a couple of pictures. Mine are wearing on the leading shoes. .20 vs .30 on the rear. I can pry both shoes but the rear is much more difficult to move. No rust or anything like that affecting them. Just the stiff springs as far as I can see.
pic1
pic2

Dennis