Electric Trailer Brake Replacement Part
Standard Electric Brake Magnet Trailer 5.2k - 7k Axle "Black Wire"
Replacement electric brake magnet kit for most 5,200 lb to 7,000 lb trailer axle brake assemblies. Includes the magnet, spring, and clip for service replacement on compatible electric trailer brake systems.
Part Number: 77M-12 5.2K–7K Axle Rating Magnet + Spring + Clip
Key Measurements & Specs
| Specification |
Detail |
| Part Number / SKU |
77M-12 |
| Brand |
Standard aftermarket replacement |
| Product Type |
Electric trailer brake magnet kit |
| Magnet Dimensions |
3-1/8" L x 2" W x 1" H |
| Wiring |
3" encased wire with 19" leads |
| Quantity Included |
One magnet, one spring, and one clip |
Fitment / Application
| Category |
Details |
| System |
Electric trailer brake system |
| Primary Fit |
Most 5.2K–7K trailer axle brake assemblies |
| Wire Configuration |
2-wire magnet lead configuration |
| Fitment Method |
Verify axle rating, brake size, magnet shape, lead length, and spring/clip style before ordering |
| Important Note |
Comparable to Dexter-style magnets by application reference only; verify before ordering |
Top Features
| Feature |
Buyer Benefit |
| 5.2K–7K Application |
Covers a common heavy-duty trailer axle brake service range |
| 2-Wire Design |
Matches standard electric trailer brake magnet wiring layouts |
| Service Kit |
Includes the magnet, spring, and clip needed for magnet replacement |
| Dexter-Style Reference |
Useful replacement option where the dimensions and brake assembly match |
Overview
This 77M-12 electric trailer brake magnet kit is designed for service replacement on compatible 5.2K to 7K trailer axle electric brake systems. The kit includes one brake magnet, one spring, and one clip. It is a practical replacement option when the existing magnet is worn, damaged, shorted, or no longer providing proper brake engagement.
R&P Service Insight
Brake magnets are wear items inside electric drum brake assemblies. Before replacing only the magnet, inspect the full brake assembly and drum face so the new magnet is not installed against a damaged or uneven surface.
-
Check the drum face: A grooved or damaged armature surface can shorten magnet life.
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Inspect wiring: Look for broken insulation, weak connections, or damaged leads before installation.
-
Confirm brake size: Match the magnet to the axle rating and brake assembly before ordering.
R&P Knowledge Hub
Compatibility: Fits most 5.2K–7K trailer axle electric brake assemblies where the magnet dimensions, wiring, and spring/clip configuration match.
Vehicle / System Fit: Intended for electric trailer drum brake systems, not hydraulic surge brake systems or disc brake systems.
Installation Notes: Verify the existing magnet shape, brake assembly style, lead length, and mounting hardware before ordering.
Performance Insight: The brake magnet is the electrical contact point that helps actuate the brake shoes when voltage is applied through the trailer brake system.
Brand & Fitment Note
Selling Brand: Standard aftermarket replacement
Application Reference: Dexter-style references describe compatibility style only and do not indicate that this is a genuine Dexter OEM part.
What This Means: This listing is for an aftermarket electric trailer brake magnet kit, not a guaranteed OEM-branded item unless specifically stated and verified.
Before Ordering: Verify axle rating, brake assembly size, magnet dimensions, spring and clip style, wire configuration, and lead length before installation.
R&P Repair Insight
If trailer braking is weak or uneven, the magnet may be only one part of the issue. A complete brake inspection should include the magnet, shoes, drum surface, wiring, grounds, brake controller output, and adjustment condition.
-
Magnet Wear: Replace the magnet if it is heavily worn, cracked, damaged, or electrically faulty.
-
Brake Adjustment: Proper shoe adjustment is still required for good brake response.
-
Electrical Check: Confirm brake controller voltage and trailer wiring continuity before assuming the magnet is the only problem.
Features
Fits Most 5.2K–7K Axles
Built for common electric trailer brake applications in the 5,200 lb to 7,000 lb axle range.
Electric Brake Compatible
Designed for standard electric drum brake systems using a 2-wire magnet connection.
Service Replacement Kit
Includes the brake magnet, spring, and clip for a focused magnet replacement service.
Dexter-Style Application Reference
Comparable to Dexter-style magnet applications where the brake assembly and measurements match.
Included Components
| Quantity |
Item |
| 1 |
Brake magnet |
| 1 |
Spring |
| 1 |
Clip |
Important Fitment Note: Verify axle rating, brake assembly size, magnet dimensions, wiring style, lead length, and spring/clip configuration before installation. Dexter-style references are application references only and do not indicate OEM status unless specifically stated and verified.
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