How to Find Replacement Electric Drum Brakes for a Trailer

Updated 07/17/2020 | Published 10/24/2018

Products Featured in This Question

etrailer Electric Trailer Brakes - 10" - Left/Right Hand Assemblies - 3,500 lbs

(734)

$132.75

etrailer Electric Trailer Brakes - 12" - Left/Right Hand Assemblies - 5,200 lbs to 7,000 lbs

(600)

$152.82

Question:

Electric drum brakes how is the best way to measure to put brakes on a boat trailer that I cannot identify the axle

asked by: David

Expert Reply:

If you need to find the size of the correct replacement braking assembly for your boat trailer you will need to remove the trailer hub and measure the inside contact patch with the shoes which you can see in the attached photo. You will also want to make note of how many bolts hold the braking assembly to the axle. The most common two are the Electric Trailer Brake Kit part # AKEBRK-35 for 3,500 lb axles with a four bolt brake mounting flange or the Electric Trailer Brake Kit part # AKEBRK-6 for 5,200 - 7,000 lb axles with a five bolt brake mounting flange.

If you do not have access to the drum then the only options I have are to either first count the number of brake mounting flange bolts and then measure the axle diameter or call the trailer manufacturer with your VIN. If you have to measure the axle diameter you can use the below chart to determine weight capacity but please keep in mind this only works for leaf spring axles. I have attached a list of our braking assemblies for you as well.

- 1,000-lb - 2,000-lb Axles: 1-1/2 inch - 1-3/4 inch diameter
- 3,500-lb Axles: 2-3/8 inch diameter
- 6,000-lb - 7,200-lb Axles: 3 inch diameter
- 8,000-lb Axles: 3-1/2 inch diameter
- 9,000-lb Axles: 4 inch diameter
- 10,000-lb + Axles: 5 inch diameter

expert reply by: Conner L

click to enlarge

George W.

7/13/2020

I have 10" electric brakes and I have manual adjustment can I order self adjusting

Chris R.

7/17/2020

Absolutely. The self-adjusting mechanism is on the brake assembly itself - so there's nothing on the trailer that you need to switch up to make this change. The etrailer # AKEBRK-35-SA will work great.