Converting Electric Brakes to Electric Over Hydraulic Tandem 10K Axles

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Question:

Hi, I have a trailer with two 10,000 lb axles. It currently has electric brakes and I would like to convert it to electric over hydraulic. Is there a kit or parts list that I need to do this? Thanks.

asked by: Glen G

0

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.

Answer 1

Hey Sara. To replace your Hydrastar Electric Over Hydraulic Actuator for Drum Brakes item #HBA-12, I recommend the Deutsche Hydrapro Alpha G-1200 item #DH34FR. Not only is it more durable with better internal mechanisms it's also noticeably…

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Answer 2

Hey Maurice, The first thing I want to confirm is that you have disc brakes and not drum brakes? The Dexter DX Series Electric Over Hydraulic Brake Actuator #K71-651 is designed for disc brakes and would send out 1,600psi instead of just 1,000psi…

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Answer 3

Hey Will, yes the hydraulic brake assembly part #23-325 that you referenced can be converted to electric over hydraulic by just swapping the actuator on the trailer. Our favorite option for that is the Hydrastar part #HS481-8065 which comes with all…

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Answer 4

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Answer 5

In order to determine the torque rating for the lug nuts on your trailer you will need to know check out the chart I attached that shows all of the torque specs for all the trailer lugs available based on stud size, wheel material and wheel size.

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Answer 6

According to Blue Ox, it'll take an experienced installer about 4 to 5 hours to complete the installation of their #BX1128 Base Plate Kit on a 2016 Jeep Grand Cherokee. The install isn't what I'd call super-difficult, but the installation…

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Answer 7

A 4-Way trailer connector has the basic lighting functions only; running lights, left turn signal and brake lights, right turn signal and brake lights, and ground. A 7-Way has these functions and a 12 volt circuit, a circuit for electric trailer…

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Answer 8

It sounds like you are speaking of the wires for the brake magnets. If this is correct, you will need to connect one of the wires to the brake controller output wire on your trailer connector and the other wire will need to be grounded to a clean…

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Answer 9

The #84 spindle is just a common way to identify the spindle dimensions typically used for 3,500 lb axles. So instead of listing out the parts, people can just say they have #84 spindles and it's easier to know what fits it. The CE Smith Trailer…

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Answer 10

Even though I cannot comment specifically on the grease you used because I am not familiar with it, I can tell you the best grease for trailer bearings is a a grease with a rating of GC-LB, which just means it is made to withstand very high…

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Answer 11

To determine the size of the brake assemblies you need you have to measure the depth and width of the hub drum on the axle like what you see in the picture I attached. The most common size is 2-1/4 inch wide like the #T4071600-500 that you…

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Answer 12

The Demco Hydraulic Trailer Brake Actuator part #DM72VR should be a direct replacement for the Atwood 61101 Brake Actuator that you have now. This newest updated it rated at 7K instead of 6K. This is a bolt on option that mounts on 3" centers.…

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Converting Electric Brakes to Electric Over Hydraulic Tandem 10K Axles

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