Match the part number, measurements and connection points that apply to your trailer.
| Bearings | Match inner and outer bearing numbers. |
|---|---|
| Seal | Match the seal number or dimensions. |
| Bolt Pattern | Verify the complete lug pattern. |
| Brake Size | Confirm when applicable. |
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.
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.
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.
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.
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.
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.
Engineered to withstand the extreme heat and friction of 8K-15K heavy-haul applications.
Includes magnet assembly, retainer, and spring for a comprehensive service.
Direct replacement for Dexter, Lippert, Rockwell, Carter, and AL-KO 12.25" brakes.
Pre-wired pigtails and included instruction sheet ensure a seamless setup for DIY or shop use.
| 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 |
| 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. |
| Quantity | Item |
|---|---|
| 1 | Electric Brake Magnet Assembly (Blue Wire) |
| 1 | Magnet Retainer |
| 1 | Magnet Spring |
| 1 | Installation Instruction Sheet |
Selected from R&P customer feedback for Hub / Drum products and related trailer service.
“I've ordered lots of trailer repair parts from them, always fast service, well packed, and the right parts. I highly recommend.”
“Would like to say thanks to everyone at R and P Carriages parts were delivered fast and with the very helpful staff, the right parts were sent the first time. Thanks Happy Holiday's.”
“Received swivel d-ring tie down 4 days after my wife ordered them , great price and came with backing plates. I received exactly what I paid for, thanks for the great service. Chris Davis , Mooresville NC”
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