12-1/4" x 4" Electric Trailer Backing Plate – 10K HD – Left Hand – 7 Bolt
Heavy-duty left-hand electric trailer brake assembly for 12-1/4" x 4" drum brake applications on 10,000 lb heavy-duty axle setups. Designed for 7-bolt mounting flanges and Dexter-style 10K HD applications where measurements and mounting pattern match.
Key Measurements & Specs
| Specification | Detail |
|---|---|
| Part Number / SKU | BK-10HDE-01 |
| Product Type | Electric trailer brake assembly / backing plate assembly |
| Brake Size | 12-1/4" x 4" |
| Axle Application | 10,000 lb heavy-duty trailer axle applications |
| Mounting Pattern | 7-bolt brake flange |
| Quantity Included | 1 left-hand brake assembly |
Fitment / Application
| Category | Details |
|---|---|
| Trailer System | Electric drum brake trailer axle system |
| Primary Fit | 12-1/4" x 4" 10K HD electric brake applications with 7-bolt flange |
| Orientation | Left hand / driver side only |
| Fitment Method | Verify brake size, axle rating, mounting flange pattern, drum compatibility, and left/right orientation before ordering. |
| Application Note | Dexter-style reference is for fitment guidance only. Confirm existing brake specifications before installation. |
Top Features
| Feature | Buyer Benefit |
|---|---|
| Self-Adjusting Design | Forward self-adjusting setup helps maintain brake adjustment during normal service use. |
| 10K HD Application | Built for heavy-duty 10,000 lb trailer axle brake applications where the original setup matches. |
| 7-Bolt Mounting | Matches 7-bolt brake mounting flanges used on compatible heavy-duty axle assemblies. |
| Left-Side Replacement | Useful when replacing only the driver-side brake assembly or matching with the right side for axle service. |
Overview
BK-10HDE-01 is a left-hand electric trailer brake assembly for 12-1/4" x 4" 10K heavy-duty drum brake applications. It is configured for 7-bolt brake mounting flanges and is intended for compatible Dexter-style 10K HD axle setups where the brake size, flange pattern, and orientation match the trailer being serviced.
R&P Service Insight
Heavy-duty brake assemblies should be matched by measurement and side orientation, not by axle rating alone. Before ordering, compare the existing brake assembly against the size, mounting pattern, and left/right layout listed here.
- Brake Size: Confirm the drum brake size is 12-1/4" x 4".
- Mounting Flange: Confirm the axle uses a 7-bolt brake flange.
- Side Orientation: This listing is for the left / driver side brake assembly only.
R&P Knowledge Hub
Compatibility: Designed for compatible 10K heavy-duty electric drum brake applications using a 12-1/4" x 4" brake size and 7-bolt mounting flange.
Vehicle / System Fit: Trailer axle electric brake systems on matching 10,000 lb HD axle setups.
Installation Notes: Verify the existing brake flange, drum size, magnet wiring, and left/right brake orientation before installation. Mounting hardware is not listed as included.
Performance Insight: Self-adjusting brake assemblies are commonly used to help maintain brake shoe adjustment under normal service conditions, reducing the need for manual adjustment when installed and functioning correctly.
Brand & Fitment Note
Selling Brand: R&P Carriages / listed aftermarket trailer brake assembly.
Application Reference: Dexter-style and 10K HD references describe compatible application style only where measurements and mounting points match.
What This Means: This listing is for one left-hand electric trailer brake assembly, not a guaranteed OEM-branded item unless separately stated and verified on the product packaging or invoice.
Before Ordering: Verify brake size, mounting pattern, axle rating, drum compatibility, left/right orientation, and included components before installation.
R&P Repair Insight
When servicing heavy-duty electric brakes, it is often best to inspect both sides of the axle. Uneven wear, weak magnet pull, damaged wiring, contaminated shoes, or an incorrect left/right replacement can affect braking performance.
- Left vs. Right: This is the left / driver side assembly. Pair it with the matching right side when servicing both ends of the axle.
- Drum Match: Confirm the brake drum is compatible with 12-1/4" x 4" shoes before installation.
- Electrical Check: Inspect wiring, grounds, brake controller output, and magnet connections during replacement.
Features
12-1/4" x 4" Brake Size
Configured for heavy-duty electric drum brake applications using a 12-1/4" diameter by 4" wide brake setup.
10K Heavy-Duty Application
Built for compatible 10,000 lb heavy-duty trailer axle brake systems where the axle and drum specifications match.
7-Bolt Mounting Pattern
Designed for 7-bolt brake mounting flanges commonly used in compatible heavy-duty trailer axle applications.
Forward Self-Adjusting
Self-adjusting electric brake design helps maintain proper brake adjustment during normal trailer service use.
Left-Hand Assembly
This listing is for the left / driver side brake assembly only. Confirm side orientation before ordering.
Dexter-Style Fitment Reference
Compatible with listed Dexter-style 10K HD applications where brake size, mounting pattern, and assembly layout match.
Included Components
| Quantity | Item |
|---|---|
| 1 | Left-hand 12-1/4" x 4" electric brake assembly / backing plate assembly |
| Not Included | Right-hand brake assembly, pair set, drums, bearings, seals, mounting hardware, and additional axle service components unless separately shown or stated. |
