MTFCA Forum

I have a new brake drum. The step between the drum and the drive plate is about .015”. I am concerned that this might wear or shred the lining. I was going to use NOS Scandinavian linings,but am having trouble finding them in good condition. My next choice is Kevlar, but I have read that they do not like to run on a brake drum with a step.
The picture makes it look worse than it is.
I am trying to decide on using Kevlar,look harder for Scandinavian, or try to find a better drive plate.

John

A better picture.

If that is the only concern, then putting the plate on a lathe and taking a light cut to either smooth it up or actually match the OD of the brake drum and then break the edges and you're good to go. The "step" per se is not a problem. Roughness is.

Can't really tell, is your drive plate bigger or smaller in diameter than your brake drum? Smaller shouldn't be a problem and bigger is easily fixed, as Scott states.

The drum is bigger than the plate. The step from drum to plate is .018. Do I understand correctly that the step is OK as is?

Typically on the small brake drum the band lining can run over a bit of the flange of the driving plate.

Just confirm the correct driving plate part is being used. Plus check that plate for warp, could be off some.

As posted, cleaning the edge up with a lathe is probably best. But the lining when it shifts to run up on the flange of the driving plate, it will burnish in that edge

I was going to use NOS Scandinavian linings,but am having trouble finding them in good condition.

Cotton deteriorates with age. It doesn't have to wear out. It gets rotten just sitting.

Kevlar lining is 11/8" wide and a pre-26 drum is 1". If you want to smooth the edge of the plate and put a little radius on the drum edge I think that would be OK, but I wouldn't take anything off the drum surface.

John Illinois wrote: ↑

Wed Apr 15, 2020 1:05 pm

The drum is bigger than the plate. The step from drum to plate is .018. Do I understand correctly that the step is OK as is?

I think it's fine. Polishing and a slight radius as Steve suggests certainly wouldn't hurt a thing however.

Thanks all. I will radius the edge of drum and polish the edge of the plate.


John

So long as the plate is larger than the drum, I wouldn't even bother with the edge of the drum. It will have no effect on the band material as the material has no way to "wrap" the corner. Simply smoothing/polishing the edge of the plate and breaking its edges would be sufficient. You just don't want to snag the material.

Have you considered wooden bands? I have used all 3 styles ( Kevlar, Scandinavian and wood) and, by far, I prefer the wooden bands. They would not be affected in any way, by a lip. Jim Patrick

To my eyes the pitting in the driven plate edge is not insignificant. Polishing will smooth the surface between the pits, but the pits will still be there to chew away at the band lining. I would be looking for a better drive plate that does not need any attention to the edge. As others have indicated, a step down to the plate surface is of little concern, but having the two at the same diameter is the goal.
In the absence of reproduction drive plates, the best answer is to substitute a wider 26-7 drum and drive plate combination.

Allan from down under.