How to Determine if Trailer Brake Magnets/Brake Assemblies and Hub and Drums Need to Be Replaced

Updated 03/02/2016 | Published 03/01/2016

Products Featured in This Question

Electric Trailer Brake Assembly - 10" - Left Hand - 3,500 lbs

(255)

$58.14

Electric Trailer Brake Assembly - Self-Adjusting - 10" - Left Hand - 3,500 lbs

(373)

$73.38

Electric Trailer Brake Assembly - 10" - Right Hand - 3,500 lbs

(273)

$56.50

Electric Trailer Brake Assembly - Self-Adjusting - 10" - Right Hand - 3,500 lbs

(378)

$56.10

Easy Grease Trailer Hub and Drum Assembly for 3.5K Axles - 10" - 5 on 4-1/2 - Pre-Greased

(1986)

$99.77

Trailer Hub and Drum Assembly - 3,500-lb Axles - 10" Diameter - 5 on 4-1/2 - Pre-Greased

(1360)

$90.62

Question:

I have an enclosed dual axle carmate trailer with 4 electric dexter brakes. The brakes are 10 x 2 1/2. I recently tested my magnets by using a multi meter between the brake controller blue wire and the blue wire coming from the outlet at the rear of the vehicle. Essential bridging the two wire together via the multi meter. I got a reading of .025. Is that correct ? When the brakes are depressed a screw driver sticks to the magnet but just barely. I have included a photo of my multi meter and my magnets. My magnets seem worn uneven and are kinda scared. I have a picture of the drums also. The drums are worn uneven where the magnet touches. Do they need to be replaced? I cant seem to upload my other pictures. Is there another way to send them?

asked by: Jarrod

Expert Reply:

The way you are describing testing your brake magnets is the way we recommend testing the brake magnets, by connecting the multimeter to the blue brake wire behind the brake controller. When testing your trailer with 4, 10 inch brake drums, the maximum amperage should be between 15.0-16.3 amps at 12-13 volts. Assuming the appropriate voltage is reaching the brakes, the 0.025 amps reading is much too low for your trailer brake magnets. I have attached a help article on testing brake magnets for proper function for you.

Since both the magnets and the drum have uneven wear, it is best to replace both the brakes and the hub and drums. If only the magnets are replaced, the uneven wear on the drums can still cause problems braking.

Going off the size brake assemblies on your trailer, it is likely that you have 3,500 pound axles on your trailer. The etrailer.com Electric Trailer Brake Assembly # AKEBRK-35L that you referenced is a great option to replace the left-hand brakes on your trailer. For the right hand side, you will want to use # AKEBRK-35R. For a self-adjusting option that will not require you to make adjustments to the brakes, I recommend # AKEBRK-35L-SA and # AKEBRK-35R-SA.

I recommend replacing the hub and drums with our etrailer.com Trailer Hub and Drum Assemblies, like # AKHD-545-35-K. This hub and drum has a 5 on 4-1/2 inch wheel bolt pattern, uses a L68149 inner bearing, L44649 outer bearing, and 58846 grease seal. If your trailer has EZ Lube Axles, you can use the # AKHD-545-35-EZ-K hubs. You will want to check the bearings and grease seal, as well as the wheel bolt pattern of your existing hubs to ensure the replacement hub and drum will fit. If your hub and drums use different inner or outer bearings or a different grease seal, feel free to let me know and I will be happy to make a more specific recommendation.