Hot brake behavior

I'm experiencing some vibration/pulsation (thrumming?) that you can hear/feel when braking. It seems to show up when I've been braking relatively firmly. Light or gentle braking doesn't bring it on. I checked the shoes a couple of years ago (very few miles since then) and both sides had adequate lining. I believe the brakes are in good adjustment.

I assume these symptoms are due to the brakes getting warm. The only factors I can think of are:
1. somewhat warped drums
2. Prodigy set too aggressively (trailer working too hard). I have it set on "B-1" and have the brake power wheel set fairly high. As this is the only trailer with brakes that I've towed, I don't know how it "should" feel when properly set up. Seems like stopping distances are too long with the power set lower. While I realize I can't stop as quickly with a trailer as without, I still want to have some ability to handle emergencies...

Maybe I should have the drums turned? Anyone else experience this sort of thing?

Thanks in advance,

Steve

[mjlaupp]

I am assuming you are talking about the trailer brake drums. In any case, One thing that can cause what you are describing is uneven tightening & torquing of the lug nuts. If you do not use a star pattern and several passes to get the lug nuts tight, you can induce warping in the brake drums and/or disks. This is most apparent at high braking pressures. I have had this problem with several vehicles after a visit to various tire shops. Those air impact wrenches in the hands of a tyro can do more damage than good. In fact, they twisted a lug bolt off of my Trooper and stretched several more that had to be replaced. Try loosening the lug nuts and retighten them using a star pattern and several passes. This may stop the pulsing.
Mike

It's best to use a torque wrench so you don't over-tighten the lug nuts. That is especially bad for disc brakes. You can warp a rotor in 2 seconds if you tighten the lug nuts unevenly - as most tire shops seem to do. I don't let any shop tighten my lug nuts - I carry a torque wrench in my vehicles when traveling. At home I always use a torque stick (extension) and an air wrench. the torque stick limits the torque applied to the nut by flexing when it reaches the torque specified on the extension.

Yes, I was referring to the trailer brakes, not the TV. I should have clarified that better. And thanks for the torquing suggestions. Since I've owned the TM, I've always used my torque wrench in a star pattern (95 ft lbs if I remember correctly). That's not to say that the previous owners couldn't have caused some warpage, but I don't recall this vibration being quite this pronounced last season.

Steve

[commodor47]

Maybe the bearings are causing the problem? Might be worth checking into. Could it be a result of an unbalanced tire? Maybe you lost a balance weight? It might be a problem with the tire . . . uneven wear, sidewall damage (you might need to remove the tire for a closer inspection).

I just installed new Goodyear Marathons & had them balanced. I did notice when I watched the guy balancing them, that one tire was relatively "smooth" as it spun, while the other seemed to have a fair amount of "runout". They both did balance to zero, though. I will check to see that all weights are still present.

I have noticed that one hub runs maybe 10-15 degrees warmer than the other, but both have been below 130 deg. (According to Dexter, anything over 200 deg. is cause for concern.) I do recall that one hub was a shade looser than the other when I last assembled them after checking brakes. I think it had to do with the position of the castle nut if I recall.

Thanks for the suggestions - I'll check my weights and reconfirm the bearings before our next trip later this month.

Steve

Originally Posted by Steverino

I
I have noticed that one hub runs maybe 10-15 degrees warmer than the other, but both have been below 130 deg. (According to Dexter, anything over 200 deg. is cause for concern.) I do recall that one hub was a shade looser than the other when I last assembled them after checking brakes. I think it had to do with the position of the castle nut if I recall.

Thanks for the suggestions - I'll check my weights and reconfirm the bearings before our next trip later this month.

Steve

I had 1 hub that ran warmer than the other. I cleaned and relubed those bearings with no obvious improvement. I then did it over again to see if I had missed something, as well as the opposite side to compare slack. I noticed that the "hot" side had quite a bit more brake dust in the drum than the other side, even though I didn't have but about 200 miles on that side (the side that I had just done earlier). I then adjusted the brakes on both sides....there was quite a bit of adjustment needed on both.

Now both sides run equal temperature. I am not exactly sure what was going on, but here is my idea: I think the "hot" side that I did and then redid was due to heat transfer from the brake drum. I am wondering if my brakes were so out of adjustment on that side, that when I first braked (forward motion), that the shoe came out of the upper pivot point (which it will do with no drum on when checking the operation of the brake) and continued to rub the drum, causing the hub to heat also. When I would back it into the driveway, the shoe would reseat when the brake applied, so that when I jacked the wheel up to check the rotation, everything would seem fine. The extra amount of brake dust in that wheel makes me think something like that happened.

Ideas from others ????

Chap

[rtcassel]

In the middle of my last trip, I had turned on boost b1 on my Prodigy brake controller. Towards the end of the trip, I noticed that the hubs were warmer than usual, and since it had been almost 12 months since repacking, I repacked the bearings and adjusted the brakes. After a 20-mile highway test trip, the hubs were very hot (too hot to rest fingers on). A few days later, I remembered that I had boost b1 on. After a similar test drive with boost off, the hubs felt normal. Tekonsha's tech person advised not using boost. Does anyone use boost without getting hot hubs?