Single wheel lock-up, with very little gain

[vocoder]

Howdy,

I have a problem with one wheel on the rear axle locking up almost randomly when applying the brakes. Last weekend, I decided to do some tests.

Using the instructions widely available online and in the GMC manual, I set the brake controller to the point "just before wheel lockup' when fully activating the manual slider. For my trailer, this was at 5.5. This is the normal setting for any trip I take, but re-did the process for the purpose of this test.

Next, same road, conditions and speed, I applied the brakes gradually as if I could see the need to stop far in the distance. I could feel the trailer pull on the TV a bit, and the stop was smooth. Again, this seems to jive with normal conditions.

Next, I conducted a more aggressive stop, I wouldn't call it a panic-stop - more like one were you need to put some space between you and a vehicle that changed lanes into your path. This time, the rear-most wheel on the left side locked up.

I repeated these two tests, backing the gain down one setting at a time until I was at 2.5 - each time the same wheel locked up on the aggressive stop. Below about 4 however, I was no longer feeling that the trailer was adding anything to the braking effort during the 'normal' stops.

Does this sound like a controller problem, or is the brake system on that one wheel in need of adjustment? If so - is that something I could do myself?

Any chance the WD hitch needs adjusting to transfer more weight to the rear axle? The combo sits pretty level but I do think there's too much weigh on the steer axle...

Thanks for any and all input!
-Vocoder.

[Iwannacamp]

I would shoot for it's the only one working correctly. Bad connection/s. Bad ground/s. Not adjusted properly. Cheap checks.

[shorthorn]

Brake problem.... I wouldn't suspect controller to cause an issue with 1 brake, as it controls all 4 at the same time. Agree with above.. probably the only brake working

[HONDAMAN174]

Check adjustments first. It is also possible that the bearing seal may have given out and has gotten grease on the shoes.

[Flybob]

Check the wiring. Many of the connections to the brakes are completed with wire nuts. They are subject to moisture and dirt on a regular basis. I usually remove the wire nuts and re-strip and solder the connections and heat shrink them.

[rockfordroo]

Also check each brakes ground wire to the frame. Corrosion buildup can create a large resistance.

[vocoder]

Thank you all! I will get under there and take a look at the connections! I like the strip and solder idea also.

[jtesta1]

Sounds like a simple brake adjustment problem of the locking wheel.

[5picker]

I'd be pulling the wheels/hubs and looking closely at the one locking up.

[vocoder]

Originally Posted by jtesta1

Sounds like a simple brake adjustment problem of the locking wheel.

Originally Posted by 5picker

I'd be pulling the wheels/hubs and looking closely at the one locking up.

I've never done a drum brake job before... What would I want to look for - and what/where is the adjustment point? Thanks!

[5picker]

Originally Posted by vocoder

I've never done a drum brake job before... What would I want to look for - and what/where is the adjustment point? Thanks!

Below is similar to what you'll see when you get it apart.
Look for grease coated shoes/drums, excessive dirt or broken/lost parts.

The adjuster is at the bottom (star wheel) and is adjusted through a hole in the back (remove rubber plug) of the backing plate.

If you have never done a drum brake job before it might be wise to find someone to help guide you through the process. It is not difficult but having someone that knows and understands the whole thing can be helpful.

[bob caldwell]

Access hole on back side of brake bak'n plate that the brake shoes are mounted against......use a flashlight to look at the adjuster....might have an oblong rubber or plastic cover inserted into hole......it's what's called a star adjuster, and a screw driver or a brake spoon can be used for adjusting...one way loosens and the other tightens...but, as was said, you really need to pull the drum and see if any grease is on the shoes...to pull the drum, jack trailer up so the tire barely clears the ground, so you can rotate it, after losing lug nuts, then finish jack'n it up......remove wheel, and in center of drum will be a cap.....remove it by prying it off ( if you bend it...replace...their about a buck), remove cotter key, undo nut, pull drum off........might want to take trailer to an auto shop and watch how they do it.....if trailer has solid axles, with leaf springs, easy to jack up....with Alco independent type, rubber mounted spindle, don't let 'em jack on axle....use trailer frame. The magnet in above pic is fine....scoring not a problem.....if you had your trailer plugged into tv, and had someone push brake pedal till trailer brake lights came on, take a screwdriver and see if it'll stick to magnet...SHOULD...would also be good time to repack wheel bearings..

[Big Bill]

I'd start with amp draw at the magnets , then adj , rotate while adj to almost lock up then back off 5 clicks ,if that does help pull drums and inspect, this should b done once a year ,

[Wileykid]

Just to add, a good amount of videos online for you to get an idea on what you will find.

But most importantly, take pictures. Of everything, and every step. You won't question yourself when you put it back together with that.

Mark

[Big Bill]

Amp draw should be 2.5 engine off, 2.8 running

[Bama Rambler]

Here's a good article on e-trailer's site that outlines how to electrically check the brakes and what you should see current and voltage wise.
Testing Trailer Brake Magnets

I'd go through all the connections first to make sure they're good solid connections and then progress from there.

[vocoder]

Thanks for all of the responses... I wanted to pop back in and share an update.....

The short version is that I just picked up the trailer from service where they replaced all 4 of the brakes. It feels like an entirely new trailer now. The consensus from the service guys (NOT a dealer, but an independent trailer repair shop) was that 2 of the 4 brakes were not working as designed, and probably never had. One was alway partially applied and wouldn't fully apply, and one wasn't fully applying. They had some choice words for Forest River and their lack of quality checking and the potential wreck/injury that we were very lucky to not have.

I made several stops on the way home from the shop today. I've NEVER felt the trailer slowing me down like it does now, even on the brand new brakes that haven't broken in yet.

I had the gain set to 7.5 today and man, the rig felt solid. No lock-ups, no sway when hitting the brakes.

So... All seems to be good now and I can't wait to get on the road again for a longer drive.