Determining Boat Trailer Drum Brake Size With an Measurement of 14" Across The Backing Plate

Updated 07/08/2022 | Published 07/06/2022

Question:

Good afternoon. I need some new boat trailer brakes and the backing plate is measured at 14” diameter as well as the outside diameter of the drum, would this be considered a 14” drum or a 12”?

asked by: Jason

Helpful Expert Reply:

The diameter of a drum brake is measured inside the hub so your 14" outer diameter is most likely a 12" drum brake. Depending on the age of your axles on your trailer I may be able to look up what the manufacturer installed on the axle by the serial number. This is generally found on the tag in the center of the axle.

If you are only looking for a replacement brake assembly this is generally determined by the weight capacity of the axle. The Hydraulic Brake Kit # AKFBBRK-7-D fits on 5,200-7,000lb axles that use a 5 bolt flange. The brake size is 12" x 2" and has a Dacromet coating for corrosion resistance on a boat trailer.

If you can provide me with either the axle serial number or more details and pictures of your current hubs and brakes I can ensure you get the correct parts for your boat trailer.

expert reply by: Bud M