Converting Boat Trailer from Hydraulic Drum to Hydraulic Disc Brake for Use in Salt Water

Question:

Great site!! I plan to convert to disk brakes from drums this winter. My bolt pattern is 6 51/2. No part number stamped on bearings. Trailer is a Karavan US-4150-78 Primarily will use in saltwater. Do you have any idea what kit use? Can existing actuator and lines be used? Thanks

asked by: Dave B

Helpful Expert Reply:

Converting your boat trailer from hydraulic drum to hydraulic disc brakes will require you to match a number of components, such as the hub/rotor assemblies and the mounting flanges, and to replace certain others. The linked article covers the process and parts needed. You will be able to use your existing brake lines, if they are in good shape, but not your existing actuator. Disc brakes require higher hydraulic pressure than drums (1500 psi vs. 1000 psi) so you'll need a new actuator/coupler.

The particular kit you looked at, is a single axle kit for 3500-lb axles that uses a 5-on-4-1/2-inch bolt pattern. We do not offer a complete kit suitable for your trailer but you can still select the separate components needed as outlined in the article.

You will need to either obtain your bearing numbers or use a precision digital caliper to measure your spindles. It is essential that the new hub/rotor assemblies you select be compatible with the bearing set in your existing hubs. Bearing numbers are the best method to match new parts but the measurements, if precise and accurate, will work also. The linked photo shows where to measure your spindles.

For your bolt pattern you may want the Kodiak Disc Brake Kit - 12" Hub/Rotor - 6 on 5-1/2 - Dacromet - 5,200 lbs to 6,000 lbs # K2HR526D. If you give me the bearing numbers and seal number printed on the face of your current ones, I'd be happy to assist.

expert reply by: Adam R