Parts Needed to Add Hydraulic Brakes to Boat Trailer

Question:

I am trying to add brakes to my boat trailer. It has a 4 lug hub. Do you have a brake kit for that type of hub?

asked by: Brett D

Expert Reply:

I may have a solution for you, but you would need to verify the bearings that are in the hubs that are currently on your trailer and the pattern of the brake mounting flange on your axle; if there is not a brake mounting flange present then you would either need to replace the axle completely or have a brake mounting flange welded on to the axle. You can purchase a brake mounting flange and have a qualified welder weld them to the axle. When a brake mounting flange is welded to an axle, it must be welded square and concentric. This usually requires a jig to hold both parts in position. A trailer shop should have the equipment and personnel to weld brake mounting flanges to your axle. Assuming you've got a 2000-lbs axle (most common because of the 4 on 4 bolt pattern you mentioned), you'd want to use the # 4-34.

If your axle already has a brake mounting flange, the hubs for an axle that is 2000-lbs will likely have # L44649 bearings as the inner and outer bearings, so you can use the Trailer 4 on 4 Hub & Drum Assembly - 2,200 lbs. Axles - Hydraulic Brakes # 8-276-5 for the replacement hub and drum.

For the brakes I recommend using the Dexter Hydraulic Trailer Brake Kit - Uni-Servo - 7" - Left and Right Hand Assemblies - 2.5K # 23-398-399, which come with all of the mounting hardware included and will provide you with a high quality Dexter brake set.

For the brake line kit for a single axle trailer you'll want to use something like the Kodiak # 18SI-BLKIT, which will provide you with brake lines that are 18 feet long. You'll also need a hydraulic brake actuator like the Demco # DM72VR, which is a bolt on coupler for 2" hitch balls.

I've linked some review videos of these parts, as well as our helpful article that details the parts and process of adding hydraulic brakes to a trailer that I recommend checking out. If you want to go the route of replacing the axle completely with one that has a brake mounting flange and brake components just let me know and I can explain what you'll need to measure to determine if there is a stock axle you can use.