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Recommended Parts Needed to Convert Boat Trailer from Hydraulic to Electric Drum Brakes


Vintage Escort / Calkins build 3500lb dual axle boat trailer conversion from hydraulic to electrical brakes. Please respond and I send you some pictures. Nothing but virtual hugs Hans the farmer in Asheville NC.


Helpful Expert Reply:

Electric drum brakes are being found on boat trailers more and more these days since they are generally more cost-effective and easier to install than hydraulics.

Converting your tandem axle Calkins trailer from hydraulic to electric drum brakes means you'll no longer need brake lines or a surge coupler. You can keep your existing coupler if you like but you'll need to drill a hole through it side to side and install a bolt and nut to immobilize it. If you prefer you can install a new fixed coupler. Our main page for couplers is linked for you and this shows straight-tongue couplers like Fulton # F346000301 and a-frame types such as Bulldog # BD43805W0317.

Your 3500-lb axles will typically be fitted with 10-inch diameter x 2-1/4-inch wide brakes such as those shown on the linked page, like Dexter # AKEBRK-35R-SA right-hand brake and left-hand # AKEBRK-35L-SA. You will want to check your hub/drum size to make sure you select compatible brakes. The linked article on adding electric brakes to a trailer includes a diagram on how to measure your drums, as well as lots of other great info that applies to your project. Electric brakes are not polarized so you can use either wire as ground and hot.

You also want to select brakes that use the same mounting hole pattern as your old ones. All 3500-lb brakes we offer use a 4-bolt pattern like that on the brakes referenced above.

You will also need to wire your vehicle with a 7-way type connector and a brake controller like the excellent Prodigy P3 # 90195. Brake controllers are not vehicle-specific but their installations vary depending on how the vehicle is equipped. In a vehicle with only a 4-pole harness you'll use our brake controller installation kit # ETBC7 which includes everything needed to hardwire a controller like the P3. The kit includes the vehicle 7-way socket, wiring, connectors, circuit breakers, etc.

You will also need to install a 7-way trailer plug on the trailer, such as # H20046 from Hopkins. This is easiest by using a junction box like # 38656 which allows for convenient splicing together of the existing trailer wiring and the new 7-way plug. You'll also need ring terminals on both ends of the wiring to join them inside the junction box. Use part # DW05702-1 for the 14 to 16-gauge lighting wires and part # 44-5310A for the 12V power, ground and brake circuit. You'll also use 10-gauge wire # 10-1-1 to run the brake circuit on the trailer.

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