Troubleshooting New Electric Brake Installation on 1960s Custom Trailer

Question:

I am trying to upgrade a car trailer that was custom built in the 60s to use current brakes. The trailer is well built and has Hadco axles and surge brakes. I was able to purchase new drums and armature plates from Hado however installing them over the Dexter 10inch manual adjust brakes is not working well. The armature plate runs close to the outer edge of the shoes while the armature itself extends about 1/4inch beyond the outer edge so this means the armature is constantly dragging on the armature plate. This was verified with Prussian blue. It makes setting the bearing preload very difficult and would quickly overheat the armature and armature plate. Did I purchase the wrong brand of brakes? Can the magnet be exchanged with one that will sit flush with the outer edge of the brake shoes? Can the spring behind the armature be removed so the armature will rest out of the way? Will the brakes engage and disengage without the armature spring? If you want - I can send photos. Thanks.

asked by: Bob G

Expert Reply:

First, thank you for your recent purchases from etrailer.

The Dexter brakes you selected, 10- x 2-1/4-inch Dexter manual-adjust electric drum brakes # 23-26 and # 23-27, are the only width size in a 10-inch diameter. These are intended for a 3500-lb axle.

The brake magnet coil, or armature, is intended to contact the brake drum's inside surface at all times. It is normal for the brake magnet to extend outwards away from the trailer a bit and beyond the edge of the brake shoes. This is to ensure continuous contact with the drum surface. The spring in the brake assembly should not be modified in any way. Although we do offer many types of replacement brake magnets, swapping these out would have no effect.

The brand of brake assembly could have an effect on the installation. Backing plate designs can vary and this could be causing the fit issue.

If you are having trouble sliding the hub/drum over the brake pads to fully seat it over the entire brake assembly you can try using the manual adjustment star wheel to bring the pads inward. Please refer to the linked photo. You may also want to verify that the hub/drum assemblies you purchased are indeed 10 x 2-1/4-inch size.

You may need to swap out your hub/drums to Dexter brand parts for compatibility. The included link will show you all Dexter brand 3500-lb-rated hubs in various bolt patterns to allow you to choose the one you need. All hubs are a fit for bearing set L68149 / L44649.