How To Add Electric Drum Brakes To A Trailer Without Brakes

Question:

Is it possible to put electric brakes on a trailer that didnt have them originally?

asked by: David F

Expert Reply:

Yes, but there will be a few things you'll need to check first. You'll want to remove your wheel and check that there's a brake flange on the spindle of your axle for a brake assembly to mount to. Every part you'll need to going to be based off of the axle's specifications so you'll also want to find the axle tag as well. This is a sticker that lists the capacity of your axle and a bunch of other information. Once we have this info we can move forward picking out the right components.

For example, if you had a 3,500lb axle and there was a brake flange present you could get the etrailer Electric Trailer Brake Kit # AKEBRK-35-SA. This kit is self adjusting so once you initially "bed" (adjust) the brakes it will take care of the rest.

From there you'll need a hub/drum kit that matches the size of the brake assemblies and has the same bolt pattern as your wheels. If you had a 5 on 4-1/2 wheel bolt pattern (most common) then you could use the etrailer Easy Grease Trailer Hub and Drum Assembly for 3.5K Axles # AKHD-545-35-EZ-K. These come in a quantity of one so you would need to order multiple to cover each braking assembly. These are pre-greased, which is 100% the way to go so that the bearings are already packed with grease and ready to go right out the box. Packing bearings is a pain and giant mess so I always recommend taking the easy route and having them pre-packed.

Now that we have all that in place we can work on the wiring. You'll need to run 10AWG # 10-1-1 wire from the brake assemblies up to the junction box at the front of the trailer and will connect to the brake controller wire/post for your 7-way cable. There will be two wires sticking out of each assembly, it doesn't matter which is used for what but one will be power running to the junction box and the other can just get grounded right to the frame of the trailer.

I recommended using heat shrink butt connectors # DW05745-10 to ensure a waterproof connection for your wires.

You'll need to also install a breakaway battery kit like the Bright Way Push-to-Test Trailer Breakaway Kit with 1-Amp Charger and 5 Ah Battery # 3802308. In the event of a breakaway the battery will activate the brakes to help bring the trailer to a controlled stop instead of rolling loose on the highway.

Once this is complete the trailer side will be complete but you'll need to ensure that the tow vehicle has a 7-way on the back of it and a functioning brake controller in the cab. If you need help picking out these items then just let me know the year/make/model of your vehicle.

I've attached our help article on adding electric drum brakes below which explains all of this in further detail. If you can get me more information on your trailer I'd be more than happy to pick the correct parts out for you and walk you through the installation process more if needed. This is something you can easily do yourself if you don't want to pay someone.