Electric Brake Magnet for 12-1/4" Dexter & Universal 8K-15K Axles
Restore heavy-duty stopping power with this OEM-spec magnet kit, designed for high-stress 12-1/4" electric brake assemblies on 8,000 to 15,000 lb axles.
Overview
The 77M-1210 (Interchange 71-378) is a heavy-duty replacement magnet designed to provide consistent braking force for trailers equipped with 12-1/4" electric drum brakes. This kit is a high-quality replacement solution designed for major brands including Dexter, Lippert, and Rockwell, making it an essential service part for goosenecks, lowboys, and heavy cargo trailers.
R&P Service Insight
Worn magnets are the #1 cause of weak or surging trailer brakes. Replacing the magnet restores the electromagnetic pull required to actuate the brake shoes.
- Versatile: Fits both Left and Right side assemblies (Non-handed).
- Universal Fit: Cross-compatible with Lippert, Rockwell, and AL-KO.
- Easy Install: Includes a pre-wired blue pigtail for faster splicing.
R&P Knowledge Hub
Compatibility: Dexter 12-1/4" x 3-3/8" electric brakes manufactured after June 1992.
Vehicle / System Fit: Optimized for 8,000 lb, 10,000 lb, 12,000 lb, and 15,000 lb heavy-duty axles.
Installation Notes: Verify your drum diameter (12.25") and axle capacity before ordering. Not compatible with 3.5K or 7K (12" x 2") systems.
Performance Insight: Features a high-tensile spring and secure retainer to ensure the magnet maintains proper face-contact with the armature plate for immediate braking response.
Brand & Fitment Note
Selling Brand: R&P Carriages / Verified Aftermarket Replacement
Application Reference: Any OEM or platform names like Dexter, Lippert, or Rockwell describe compatibility and application style only.
What This Means: This listing is for an OEM-spec replacement magnet kit, designed to match the fit and function of Dexter K71-378-00.
Before Ordering: Please verify your brake diameter is 12-1/4" and your axle is rated between 8,000 lbs and 15,000 lbs.
R&P Repair Insight
When replacing magnets, always inspect your brake drum’s armature surface. Deep scoring or uneven wear on the drum will cause new magnets to fail prematurely.
- Wire Check: This assembly features blue lead wires; ensure proper grounding during installation.
- Brake Type: Fully compatible with both Manual Adjust and Self-Adjusting brake styles.
- Axle Specifics: Fits 4" and 5" (15K) brake configurations specifically.
Features
Heavy-Duty Build
Engineered to withstand the extreme heat and friction of 8K-15K heavy-haul applications.
Complete Kit
Includes magnet assembly, retainer, and spring for a comprehensive service.
Universal Compatibility
Direct replacement for Dexter, Lippert, Rockwell, Carter, and AL-KO 12.25" brakes.
Installation Ready
Pre-wired pigtails and included instruction sheet ensure a seamless setup for DIY or shop use.
Specifications
| Specification | Detail |
|---|---|
| Part Number | 77M-1210 |
| Product Type | Electric Brake Magnet Kit |
| Brake Size | 12-1/4" x 3-3/8" |
| Axle Rating | 8,000 – 15,000 lbs |
| Wire Color | Blue (Pigtail Lead) |
| Side | Universal (Left or Right) |
| Interchange | 71-378, K71-378-00 |
Fitment / Application
| Category | Details |
|---|---|
| Brake System | 12.25" Electric Drum Brakes |
| Primary Fit | Dexter Axles (Post 6/92) |
| Axle Types | 8K, 10K, 12K, 15K Units |
| Notes | Fits 4" and 5" (15K) brake configurations. Not for 12" x 2" brakes. |
Included Components
| Quantity | Item |
|---|---|
| 1 | Electric Brake Magnet Assembly (Blue Wire) |
| 1 | Magnet Retainer |
| 1 | Magnet Spring |
| 1 | Installation Instruction Sheet |
