How to Measure to Determine the Size Trailer Brakes Needed For Hydraulic Drum Replacement
Updated 09/04/2025 | Published 05/14/2017 >
Question:
Where does the measurement come from to determine if I have 2-1/4 or 2-1/2inch brakes? I need to replace the brakes on a Road King boat trailer with 3700# axles. It seems the wheel cylinder is blown out and rather than buying piece parts you kits seem to be the best option.
asked by: Chris
Helpful Expert Reply:
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 referenced.

Joe C.
9/4/2025
10" x 2.5" - double axle can you give me a part number



Product Page this Question was Asked From
Dexter Hydraulic Trailer Brakes - Free Backing - 10" - Left/Right - 3,750 lbs
- Trailer Brakes
- Hydraulic Drum Brakes
- Standard Grade
- Free Backing
- Manual Adjust
- Single Servo
- 10 x 2-1/4 Inch Drum
- 3750 lbs Axle
- 14 Inch Wheel
- 14-1/2 Inch Wheel
- 15 Inch Wheel
- Dexter
more information >
Continue Researching
- Search Results: trailer brakes
- Search Results: trailer hubs and drums
- Search Results: grease
- Shop: etrailer Electric Trailer Brakes - Self-Adjusting - 12" - Left/Right Hand - 5.2K to 7K
- Shop: Dexter Electric Trailer Brakes - 12" - Left/Right Hand Assemblies - 7,000 lbs
- Shop: Dexter Nev-R-Adjust Electric Trailer Brakes - 10" - Left/Right Hand Assemblies - 3.5K
- Shop: etrailer Electric Trailer Brakes - Self-Adjusting - 10" - Left/Right Hand Assemblies - 3.5K
- Shop: etrailer Electric Trailer Brakes - 10" - Left/Right Hand Assemblies - 3,500 lbs
- Shop: Easy Grease Trailer Hub and Drum Assembly for 3.5K Axles - 10" - 5 on 4-1/2 - Pre-Greased
- Shop: Trailer Wiring
- Shop: Dexter Electric Trailer Brakes - 10" - Left/Right Hand Assemblies - 3.5K
- Search Results: trailer bearings races seals caps
- Search Results: 12 electric brake assembly
- Shop: Trailer Hitch
- Search Results: accessories and parts
- Search Results: transport chain
- Video: Review of etrailer Trailer Hubs and Drums - Hub with Drum - AKHD-545-35-EZ-K
- Shop: Fifth Wheel Hitch
- Shop: Brake Controller
- Shop: Base Plate for Tow Bar
- Q&A: Replacement Brakes And Drums For A 7k Rated Sloan Kwik Load Trailer
- Article: Trailer Wiring Diagrams
- Video: Let’s Check Out the Dexter Electric Trailer Brake Assembly
- Video: A Look at the Terran Industries Trailer Hub and Drum Assembly
- Q&A: Looking for Brake Line Kit for 2020 Bass Tracker 20 ft Boat Trailer
- Video: Installing the Dexter Nev-R-Adjust Electric Trailer Brakes on a 2020 Taxa Mantis Travel Trailer
- Article: How to Tell the Weight Rating of a Trailer Axle
- Shop: Vehicle Tow Bar Brake System
- Video: Review of etrailer Trailer Brakes - Electric Drum Brake Kit - AKEBRK-35-SA
- Shop: Suspension Enhancement



Matt O.
8/7/2020
12 x 2.5 drum trisaler brakes i just want the whole brake whitout botor i need probably 5