Need Help –Brake Drum HOT!

[Mookie]

I installed 4 brand new brake backing plates about a month ago. I took my time and did a nice job soldering the connections. Since then, the rear curb-side brake drum gets very hot when the other 3 are barely warm. I have replaced the bearings with brand new Timken bearings and races – brake drum still hot. I have backed off on the brake adjustment – brake drum still hot. Do you think I have a defective magnet? Any idea on what is my problem?

[sfixx]

Originally Posted by Mookie

Any idea on what is my problem?

I'm guessing that you need to do some more testing to isolate the problem. Did you have the drums turned too? It sounds like it's not the brakes if you've really got the shoes backed way off. How could a magnet be bad and grab with no power to it?

How long does it take to get hot, minutes or hours? Starting with cool brakes can you run down the highway for 10 minutes and coast to a stop...if it's still hot try the same thing with no power(electricity) to the brakes. I think that you would then be sure that it's NOT the brakes or magnet but bearings.

I set and tested my new backing plate assemblies with the wheels off the ground so that I would be sure that none were dragging

Best of luck,

Steve

[Mookie]

Thanks Steve. Bearings and races are brand new. Brake drum doesn't seem to get hot during highway driving - seems to be local stop and go, up and down hills that really makes the drum get hot. I did test everything while the wheel was off the ground. Brakes seemed to work fine, but I could hear the magnet rubbing a little against the drum.

-Mark

[john hd]

mookie

welcome to the forum, backing plates are right and left assemblies. any chance you got a left where a right should be?

simple stuff first!

john

[Mookie]

Thanks John,
I'm certain the assemblies are on the correct sides. One thing I haven't checked yet is how much voltage and amperage is going to each backing plate. I suppose if I've got the correct voltage and amperage going to the backing plate, the magnet may be defective.
-Mark

[john hd]

how about pulling the offending hub and checking that the brake shoes are tapered properly on the leading edges? they should have a 45 degree bevel on them.

if the edges of the shoes are not tapered properly, they will self apply! no matter how much you back them off!

john

[Mookie]

John,
Is tapering something that I should have done when I replaced the brakes, or should they come from the factory tapered? Should I take a file and ease the leading edge of the brake shoe?
-Mark

[john hd]

mookie

yes, yes, and yes! you are correct on all of your statements!

if you decide to file the shoes wear a resperator or a good mask! even though asbestos is outlawed, you never know! especially if the shoes are imports!

john

[nickcrowhurst]

Mark, I had a similar problem. It turned out to be the large flat actuating lever catching on another part inside and jamming the brakes on intermittently. The parts were new, and the problem was a change in design of the actuating lever. I would swap the positions of two back plates and complete assemblies, and see if the problem followed the backplate. Sorry about redoing the soldering, but you would need to do that to check the amperage! As the others have said above, you need to isolate the problem. If it's the backplate, I would return it to the store for a replacement. I've spent far too long trying to get a defective brake assembly to operate correctly. Good luck. Nick.

[Mookie]

Hi Nick,
You know, I noticed this weekend that the actuating lever on this particular backing plate seems sloppy - more so than the other ones. It seems to have a lot of unnecessary play. I thought about swapping to see if the problem follows the backing plate. Although this seems like a lot of work, it's starting to look like I may end up doing it. I'm going to start with tapering the leading edges of the brake shoe like John suggests to see if that makes a difference.
Thanks,
-Mark

[nickcrowhurst]

Mark, excessive slop in the actuating lever suggests to me that the return springs aren't doing their job properly, allowing the brake shoe to stay in contact with the brake drum. If the springs are not snagged on anything, perhaps a spring is defective. Let's hope filing the leading edge works. Nick.

[Mookie]

I think I finally have the fix to this problem. I originally wanted new backing plates because it was apparent that the brakes on my trailer had been serviced numerous times - and there were issues. Besides the sloppy wiring and incorrect springs, a couple of seals had failed and the backing plates were coated with grease. My assessment was that brand new Hayes backing plates, all around, would clean this up and make our travels much safer.

After installing the new Hayes backing plates the two curb-side brake drums were running very hot - one in particular was consistently 40-50 degrees hotter than the street-side brake drums. To isolate the problem, I did the following:

1. Installed new Timken bearings and races
2. Turned the drums
3. Filed the leading edges of the brake shoes
4. Fit the brake shoes to the drums
5. Checked the voltage and amperage at the backing plate
6. Swapped the curb-side backing plates

What I found was that the problem followed the backing plate. I went to a different trailer supply house and bought new curb-side Hayes backing plates. One immediate observation, the magnet actuating lever was no where near as sloppy on the new(er) backing plates. I installed the plates - problem solved.

This whole operation took almost 2 months to complete - it was a major pain. Every weekend I was trying something different in order to isolate the problem. Words to the wise - when we purchase new parts, we typically assume that the manufacturer employs quality control procedures on the assembly line to reduce defects. However, we all know what Groucho Marx said about the word 'assume'.

Thanks to everyone for helping me resolve this problem.

-Mark

[nickcrowhurst]

Mark, what a relief it is when it finally works. When it happened to my trailer, I dismantled the offending assembly about twelve times over a one month period, in the middle of a field of fire ants. Again it was new parts that were faulty. Well done! Nick.