Converting Electric Brakes to Electric Over Hydraulic Tandem 10K Axles  

Question:

Expert Reply:

Thanks for letting us help Glen. To determine the correct brake assemblies for your trailer, we'll first need to confirm the dimensions of your existing brake drums:

If you have 12-1/4" x 3-3/8" drums, you'll need the Dexter Hydraulic Drum Brake Assemblies # 23-410-411
If you have 12-1/4" x 4" drums you'll need # 23-404-405

If you can reply with the part number from your hub/drum or existing brake assembly, I should be able to confirm which set you need. Each set includes brakes for one axle, so you'll need two sets if you want brakes on both axles.

For the hydraulic lines, I'd recommend the Hydrastar Hydraulic Brake Line Kit - Tandem Axle # HS496-252. It includes a 25-foot main line along with the necessary flex lines, fittings, and mounting hardware for a tandem-axle setup.

You'll also need an electric-over-hydraulic (EOH) actuator. For drum brakes of this size, you'll want an actuator rated for 1,200 PSI, such as the Hydrastar Electric Over Hydraulic Actuator for Drum Brakes # HBA-12.

There are a couple of other components you'll need, including a breakaway system and brake controller, which I'm assuming you may already have. One important thing to keep in mind is that not all brake controllers are compatible with EOH brakes. If you can send me the year, make, and model of your tow vehicle, along with any brake controller you already have, I'd be happy to confirm compatibility or recommend the correct one.

What are you typically hauling on this trailer?

expert reply by: Christopher H

0

Glen

8/19/2026

Hi Christopher, The trailer has 12-1/4" x 4" brakes. The normal tow vehicle is a 2004 International 7300 and has a brake controller that I purchased from etrailer: Hayes Air Actuated Trailer Brake Controller - Up to 4 Axles - Proportional ITEM # HA100400C. On occasion I also tow this with my 2002 Ford F-550. Could you recommend a controller for this truck? I usually haul excavators, a dozer, or a small grader with this trailer. Thank you. Glen

Christopher H.

8/20/2026

@Glen Appreciate all of the info! For the brake assemblies, go with Dexter Hydraulic Trailer Brakes # 23-404-405. These are the 4" wide drums. The Hayes Air Actuated Trailer Brake Controller is compatible with electric over hydraulic systems so that will be fine here. For the brake controller on your 2002 F-550 I would go with the Redarc Tow-Pro Liberty Brake Controller w/ Custom Harness # RED96CR. This is likely a different style brake controller than you are used to but this will be your best option for compatibility with an EOH braking system. Historically, we would have also had a Tekonsha like the P3 be we unfortunately no longer carry their products.