Need help after replacing brakes

Pull Dog · 10-05-2009, 11:15 AM

<HR>

Helped a friend replace the brake actuator assembly on one of his tandem axles. Bearing failure had overheated and damaged the old shoes and actuator magnet on one axle.

After we replaced the actuator assemblies (plate,shoes,magnet and springs as a new unit) we took it for a test drive. We adjusted the shoes for an ever so slight drag before leaving. After returning from a 10 mile run we noticed the drums were so HOT that you could not keep your hand on them for over a second!! We backed off on the adjustment and went again, same thing. We disconnected the electrical connection from the truck and went again. This time the same thing again. Keep in mind we did very little braking. Just the running on the road caused the drums to get hot. Bearings are all new and not overtight. We are both good mechanics, this is not our first rodeo.

Here is what I suspect. We should make a run on the Interstate at a safe speed and burnish in the new actuator magnets. Since they actually contact and rub the inside of the drum all of the time under slight spring tension, they will burnish or wear to a point where they will ride without generating heat. Then after a 50 mile run, we can at that point adjust the brake shoes properly.

Anyone have similar experience in swapping out the actuator assembly or replacing an actuator magnet????

I think we are being overly cautious and in panic mode over the heat.

Comments appreciated!!

mwebber78 · 10-05-2009, 11:19 AM

I don't think your being overly cautious, too much heat and you've just cooked the seals and any grease you used in the bearing re-do. SOmething doesn't sound right about this. Are you sure once plugged in that the actuator isn't pushing the pads to engage and drag more?

Wish I could help more.

Pull Dog · 10-05-2009, 11:41 AM

We made a test run with the trailer electrical connection to the truck unplugged. No brakes no tail lights. This of course was a little risky but we had to know if the brakes were receiving current and causing this problem. They continued to get hot even though they were not getting current to the magnet. The front axle has remained cool on both sides through this whole ordeal. Since the rear axle is all we replaced the actuator assemblies on both sides it is also the one with the heat. Our belief is that the actuator magnet has to burnish or wear into the drum surface before it will ride cool.

gtoguy1967 · 10-05-2009, 12:22 PM

How much if any drag is in the wheel when you try to spin it freely ? I can't imagain that it wound take that long for the magnets to come in or this would be an issue with new campers ??

Are you sure you have the right parts ? What does the drum look like where the two ride against each other. God luck

rcflyer · 10-05-2009, 12:57 PM

Time to tear down the offending wheel. Remove the drum and you will probably find some bad things. If you keep running you may end up with a fire. There is something wrong that will not correct it's self.

wattashine · 10-05-2009, 08:59 PM

if all brakes are hot check to make sure safety break away is not pulled. you should also adjust all brakes accordingly.

fhenn · 10-05-2009, 10:06 PM

I wonder if the accuator is working right sounds like it may be sticking

Pull Dog · 10-05-2009, 11:18 PM

Keep in mind it does this with theconnector disconnected from the truck for a short test drive. Rules out anything electrical. The wheel spins very very freely when that side of the trailer is jacked off the ground. It spins as freely as the front axle.......which has no problem. We only replaced the brake cluster assy. on the back axle, both sides. As to weather we have the right parts, Champion Trailer sold him these parts and I have had good luck with that company. I have replaced these brake cluster assemblies on boat trailers many times. But of course they are hydraulic not electrical activation.

Still troubleshooting..........will get back to everyone

KHUNLINDA2003 · 10-06-2009, 02:24 AM

Don't just assume you have the right parts. Once and a while even somebody who rarely makes mistakes does. We had our brakes done at a reputable shop and they put the wrong seals on and thus we had grease all over the drums and therefore no brakes. Something is wrong! One of you stand next to that tire while the other drives forward and see if you can hear anything unusual. If nothing I would dismantle the whole thing and start over with checking part numbers.

Dayle1 · 10-06-2009, 04:59 AM

I have had basically the same problem on a single wheel. First test run and the small amount of air in the hub superheated and blew off the dust cap. Also almost pushed the inner grease seal off. But part of that problem was that the drum was slightly oversized compared to the other three,

Anyway, even with the wires cut to the single magnet, it still overheated. Problem seemed to be with the magnet arm, not enough clearance between it and the cross bar between the two shoes AND the magnet was tilted such that the leading edge of the magnet would grab on the stud holes and therefore slightly apply the brakes even w/o power. I bent the arm and the tang that the magnet rides on. Of course you can't see what is really happening inside the drum, so it took several tries to fix the problem.

You may also like: