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How to Identify Brake Assembly for Triple Axle Boat Trailer  

Updated 12/22/2025 | Published 10/25/2024



Question:

I have a tri axle boat trailer that has been setting for quite sometime. Would like to get the hydraulic brakes work again. It has the model 20 hitch. It is 6 lug wheels. Any chance you could tell me what brake assembly I would need? Thanks

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Expert Reply:

Hi Scott; I don't have a way of knowing the exact brakes you need, but I can help you figure it out. Based on the 6 on 5-1/2 bolt pattern you have 3,500 lb - 6,000 lb axles. I would look on the trailer axles to see if you can find an axle tag to identify them. The capacity is probably listed. but if you don't see it the manufacturer can identify it using the serial number.

Assuming you're looking for hydraulic drum brakes you can use the etrailer Hydraulic Trailer Brakes - Uni-Servo - 10" - Left/Right - 3.5K # AKUBRK-35 if you have a 3,500 lb axle. These measure 10" in diameter x 2-1/4" wide and fit a 4 bolt brake flange. You can also try to match this up with your current brake dimensions and the brake flange if the axle tags are missing. If you have a 5,200 lb - 6,000 lb axle you can use the # AKUBRK-7. These measure 12" in diameter x 2" wide and fit a 5 bolt brake flange.

If you are replacing disc brakes it would be best to identify the bearing combination just to be sure. If you can't find this with the axle tag you can pull the hubs and look for bearing part numbers. If they are worn or missing you need to measure the inner diameter or spindle using a digital caliper # PTW80157.

The only disc brakes we have with a 6 on 5-1/2 bolt pattern are for 5.2k-6k axles. If that is what you have you can use the DeeMaxx Disc Brake Kit # DE28YR. These use a # 25580 inner and # 15123 outer bearing with a # GS-2125DL grease seal.

expert reply by:
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Robin H
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Etrailer Expert

Robin H.

12/22/2025

Hey Scott, were you able to identify your axle capacity or find the axle tag on your trailer? Knowing that would confirm whether the 10-inch or 12-inch hydraulic brakes were the right fit. Your update could really help others trying to revive older tri-axle trailers too.

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