Grabby Brakes

[ralphie]

I'm an old rv'er but new to towing a 5w and have never towed anything with electric brakes before now. After I purchased a used 5w a couple of weeks ago I removed each wheel and inspected the brakes for any issues. Didn't find anything obvious. The linings are good and the magnets are not worn, and I didn't find any bad electrical connections or obvious shorts. I cleaned everything with brake cleaner and used the proper grease where the the shoes ride on the backing plates. Have towed about 400miles since then and am experiencing occasional grabbing and lock up from one or more of the wheels when braking up to medium hard. I've adjusted the controller according to the instructions. Of course, I cannot tell which of wheels (front or back axle) is locking up other than seeing a puff of smoke from one side of the rig. Short of completely replacing each brake assembly one at a time until the problem is resolved, does anyone have any thoughts on what I can do? Or, is the problem I'm describing typical of electric brake operation?

[CD]

This probably won’t answer your question but is something that is very difficult to find. I had a problem with my 91 Pontiac. It would lock up (at low speed especially the first time you used them) one rear wheel. It had been taken back to the mechanic several times and he couldn’t find anything. I finally took it apart and took it to the parts house (that turns drums) and asked to have it turned. The lady that waited on me got out their fancy digital caliper and checked it. She looked at me and said “it looks like new”. I said turn it anyway. She looked like I had slapped her in face. When I returned to get it, the man that turned it came out and told me it had a hollow spot in the middle of it that could only be “seen” with a dial indicator. The caliper only measured the outside edge. If you can’t determine which wheel is doing it, take off the drums on the side that you see smoke and have them checked as I have described.

[Ray,IN]

There is a very good chance that wheel is doing the braking while at least one of the others is not working. Have you checked the amperage draw and voltage at each magnet? Each magnet should draw 3A when energized per Dexter Axle. (scroll down to "brakes") A better description may be found here.

While some folks curse electric brakes they are a good, safe, design-when properly maintained. Boeing is using electric brakes on their new 787, and Bombardier (Canada) is testing electric brakes on an aircraft.

[ralphie]

Thank you CD and Ray. I will check out both of those suggestions.