Trailer brake shuddering

[Sylvain]

Hello again everyone,
During our last trip with our LL I noticed some suddering/shaking while breaking withe trailer attached to the TV.  When the trailer is not attached to the TV everything is fine, no shaking.  I wonder what could cause that shaking?  I serviced the brakes and bearings before leaving for our trip.  Everything looked fine.  The brakes needed a good cleaning but the pads were good.  Does anyone experienced something similar?

Thanks

[franks97]

If you have an adjustable trailer brake control in the TV try turning it down a bit.

[Sylvain]

You may be right franks97, the higher the gain on the brake controller the more it shakes.

[charliem]

The brake controller should be set so the trailer brakes help slow the rig, not stop the rig. They should just overcome the additional weight of the TT. Instructions included with some controllers suggest starting at the point where engaging the trailer brakes manually will lock them up, then backing off just a bit. This leads to way too much trailer braking. Starting with a low setting, drive a bit and stop several times normally such as at a stop sign. With no trailer braking you will notice longer stopping distance and the trailer will feel like it's "pushing" the TV. Increase the braking until the trailer just begins to pull on the TV. You don't want the TT brakes to lock up, especially on wet or icy roads. If you have a Tekonsha or similar the boost function can be used to temporarily increase the initial attack level if you need it under some conditions. It takes a bit of trial and error but when it's right it's beautiful  .

[DavidM]

Well I disagree a little bit with Charlie's procedure above and also have a potential solution for your brake shudder. The following applies to proportional brake controllers:

I do believe in the method of adjusting the brake gain until the trailer's brakes begin to lock up and then backing off a bit. I usually do this on loose gravel so it will be less likely to lock up on wet roads.

It is a compromise but I believe it gives you the best overall braking force. If you just adjust your brakes until you feel you are getting a little pull from your trailer you aren't getting much braking force.

Back to the shudder. LL's have drum brakes and when they get very hot (more about this below) they can warp and that causes the shudder. You can have them turned in a lathe if it isn't too bad and true them up. It can be a DIY job. Pull the wheel off and then unscrew the axle nut and pull off the wheel drum. Used to be that all auto parts shops would turn drums for you, but now you have to look for one. Should cost maybe $10 per drum to get it turned. Or you can take it to an RV repair shop and have them do it all.

How did they get so hot?. Well maybe because the controls were adjusted to give too much braking force or maybe the brakes were dragging all of the time due to the internal wear adjustment getting out of whack. Once the drums are trued up, reassemble them and see if they spin easily after hitting the brakes a few times to take up the slack from the drum turning . If not back off on the brake pad adjustment.

David

[Sylvain]

Ok thanks a lot Charlie and David, it helps a lot.  I was also thinking that the drums might be warped.  The sad thing about having them turned is that I will have to remove the bearings and clean all the grease inside.  Anyway, I may end up doing just that!

[Merlin]

Sylvain, Since you mentioned the brakes needing a good cleaning, I suggest doing that first. Just pull the drums off and vacuum the shoes (with a shop vac) and use brake cleaner (with protective gear) on all the metal, especially the drums. It will be a filthy mess but it may fix the problem and even if you end up having to lathe the drums everything will need to be cleaned anyway. I had a Nissan Pathfinder several vehicles ago (here's lookin' at you David) with rear drum brakes. When they were dirty with too much brake dust they would get very "grabby" when they were the slightest bit wet. That led to shaking and shuddering even with morning dew condensation. And while you have the drums off, simply look at them to see if there are any rusted/pitted spots or spots where brake shoe material has stuck from overheating on the inside friction surface. It should be evenly polished and smooth.

[Sylvain]

Thanks Merlin,
I did clean the brakes this summer before heading out for our vacation. There was a LOT of dust in there! I removed all the dust using my air compressor but I didn't clean the drums with brake cleaner though.  I'll do that next summer before the 2020 vacation, it may solve my problem!

[Pinstriper]

This seems like a case of maybe both.

If the wheels lock up that can feel like shuddering. Obviously too much brake force going on, so adjustment is called for.

If they are not locking up but still vibrating, it is probably warp, also likely caused by too much brake force and overheating the brakes. In which case adjusting now is too late as the damage is done.

There is a caution, here. You can overheat the brakes by having them adjusted too strong, but also by the operator riding the brakes. OTOH if the brakes are set too weak you put more load on the TV brakes and can cause overheating there.

The BIGGEST thing to pay attention to is riding the brakes a lot especially in slow traffic. Your brakes heat up, then some dimwit pulls into the gap in front of you so you slam on the brakes. The hot brakes (whether drum or disc) are more prone to warpage from the extra application of sudden force. So beware that 20 mph traffic jam much as you do the mountain downhill and keep the speed off the rig.

[Sylvain]

Thanks for your input Pinstripe.  The brakes never locked up when braking.  If the gain on the brake controller is very low they still shake.  The higher the gain the more shacking though.  I really feel like the drums are warped (from previous owner) but I could be wrong.  When I turn the wheel by hand everything turns freely.  No rubbing.  That tells me that the adjustment is ok.  I wonder how he did overheat the brakes enough to warp the drums!?!  They are made of pretty thick metal.  I really want to solve this before our trip to Newfounland in July.  If they are warped, should I have them turned or just replace them?

Thanks again

[DavidM]

Try turning them. If they were not warped badly, turning should true them up. Otherwise replace them. Etrailer.com has everything you need.

It isn't difficult to DIY. Jack up the wheel. Pull off the wheel from the drum. Remove the grease cap. Pull out the cotter pin and unscrew the nut. Then pull out the drum about an inch and grab the bearing and remove it. Then the drum will come off.

Take the drum to an auto parts shop that does drum turning and get them to turn it true.

Then reinstall the drum, bearing and nut. Tighten the nut and then back off a 1/4 turn or so and put in the cotter pin, then the grease cap and pump it up with grease. Before putting the wheel back on adjust the brakes with a screw driver through the lower access hole and work the adjusting screw until it begins to drag a little. Put the wheel back on and you are done.

David

[Sylvain]

Thanks a lot David, I'll do that.  Do I need to remove the bearing race to have them turned?

[DavidM]

Thanks a lot David, I'll do that.  Do I need to remove the bearing race to have them turned?

Don't think so, but the auto parts store will press them out if necessary and press them back in place afterwards. I would clean up all of the grease first and wipe the inside with a kerosene/lighter fluid soaked rag before taking them in to be turned.

David

[Sylvain]

Ok thanks David.  This will be the first task I will tackle on the trailer in the spring.

[Pinstriper]

Thanks for your input Pinstripe.  The brakes never locked up when braking.  If the gain on the brake controller is very low they still shake.  The higher the gain the more shacking though.  I really feel like the drums are warped (from previous owner) but I could be wrong.  When I turn the wheel by hand everything turns freely.  No rubbing.  That tells me that the adjustment is ok.  I wonder how he did overheat the brakes enough to warp the drums!?!  They are made of pretty thick metal.  I really want to solve this before our trip to Newfounland in July.  If they are warped, should I have them turned or just replace them?

Thanks again

I would let the shop advise you. It could be the warp is too much to turn, or it could be fine.

Of course it could still be something else as well.


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