Old Britts
Commando Front Drum Upgrade Information
By: Fred Eaton

Summary:

This article will be assuming that you are rebuilding your front twin leading shoe drum brake completely. We will be having the following services professionally done; laced and true the wheel, Polish the hub and backing plate, the brake drum trued, and the brake shoes re-lined and arced to the drum. We will provide as much information about how to do the steps we are jobbing out and provide names of the firms that we use to perform the services we job out.

Four main performance enhancements:

These four enhancements will make your front twin leading shoe drum brake perform better than the stock Commando disc brake. If you just want to improve your front brake performance and do not want to do all four of the recommended enhancements, each enhancement will increase your performance. Just upgrading your brake shoes will improve your stopping performance. New brake shoes and upgrading your backing plate will greatly improve your stopping performance. The four enhancements are:

Rebuilding steps:

When rebuilding a front wheel, you need to perform certain steps prior to another step, so the order you should follow is:

NOTE:To true the wheel after having it laced, they like to have the bearings in the hub. To turn the brake drum, and it needs to be turned after the wheel is laced, they do not want the bearings installed. What we do is re-install the old bearings without the bearing spacer for wheel lacing, then remove the old bearings for turning the drum. This way you are not removing the new bearings, because you have to pound on the inner race of the bearing to remove them.

Spindle Bushing Upgrade:

The stock spindle bore in the backing plate is around .705" and the spindle is around .6673" or .002" under the 17mm (.6693") wheel bearing I.D. The .002" bearing to spindle clearance is what you want to achieve for the backing plate spindle bore. What I am told is that the factory increased the spindle clearance to allow for the brake shoes to self align themselves to the drum, but if the brake shoes are arced to the drum, this extra clearance is not required, and in fact lets the backing plate wobble in the drum, decreasing the efficiency of the brake.

What we do is take some .750" round 6061-T6 aluminum and bore it out to 17mm to make the spindle bushing. We then bore the backing plate spindle bore to around .748 and press the bushing into the backing plate. We then re-bore the bushing to 17mm.

Spindle Bushing

Backing plate with new spindle bushing.

Front drum brake services provided by Old Britts:

The prices are current as of 02/12/21.


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