Can I Convert My Tandem 7K Trailer Axles From Drum Brakes to Disc Brakes?

Published 09/30/2026

Question:

I have a tandem-axle trailer with 7,000-lb axles and electric drum brakes. Can I use the Hydrastar Disc Brake Conversion Kit HYD866FR to convert it to hydraulic disc brakes, and what do I need to check for fitment?

asked by: George

Expert Reply:

Hey George, thanks for reaching out. Yes, the Hydrastar # HYD866FR gives you all the major components needed to convert two 7,000-lb trailer axles from electric drum brakes to hydraulic disc brakes. This setup uses an 8 on 6-1/2" bolt pattern with 1/2" wheel studs and gives you the stronger, more consistent braking performance that makes disc brakes especially attractive on heavier trailers.

Before ordering, I recommend verifying your axle capacity, bearing combination, wheel bolt pattern and wheel-stud size, rather than going by the trailer's GVWR alone. Those details confirm that the new hubs and disc brake components match what is currently on the trailer. The best way to verify all that is with the information on your axle tag, or by providing the casting number on your hubs. I should be able to use that to look up your axle and hub info.

What kind of trailer are you servicing?

expert reply by: Jesse M