Req expert opinions about one trailer wheel locking up when braking

[gordon2]

OK I’m looking for a little advice from people much more experienced and knowledgeable about electric trailer brakes then moi.

I picked up this trailer in Sept of last year and brought it 1400 miles home. I could not lock up the brakes as the brake controller suggested so I set it on 10 volts max, no boost. The brakes seemed to work great with this setting. I did try higher boost but didn’t like it. I did not adjust the brakes at 200 miles as I later found out was recommended but I did jack up the wheels after the 1400 mile trip home and turn them. I felt a slight drag during part of the rotation and left the adjustment as it was thinking that the slight drag was from the brakes and they were in fact adjusted OK.

The first time I detected the wheel lockup was after the trailer had been parked for some weeks. I was just leaving on a short tip and when I just barely touched the brake pedal at the end of my short driveway and I heard a tire squeal. I tested the brakes a few times going down my street and they seemed fine again so I chalked it up to something sticking because it had been parked, but was free now and OK.

However the same thing later occurred after the trailer had only been parked overnight. This time it was raining so I wondered if that was the cause. Once again, except for that one lock-up, the brakes seemed to be good for the rest of the 200 miles trip.

Next trip was the big one, 1200 miles round trip and the brakes seemed to operate fine up to the last 100 miles or so but then were locking up often. I was able to tell it was only the starboard side wheel locking up and I think it was always that way although I could not tell prior to this. I also found that the hub was quite warm, really too hot to keep my finger on. I do check almost every stop and prior to this the wheels and bearing never felt hot to the touch (but of course the brake{s} were not locking up nearly as much also).

After the 1200 mile trip I adjusted the brakes by turning the star wheel until I could no longer turn the wheel then backing off six clicks. Some say to back off five, some say 10. I stopped at six because that is when I could turn the wheel with just a little effort. (Yes, maybe I should have done this sooner but it seems to be good.)

I then did a test drive of five or six miles and a few extra stopping tests in a parking lot. At first I thought that the adjustment fixed it, but then I found the starboard side would still lock up sometimes. I tried reducing maximum output on the brake controller to 4.5 volts and that seemed to help but I did still get the one wheel to lock-up. I think 4.5 is too low so I put it back to 10 volt max.

Suspecting that the wheel that was NOT locking up was maybe not braking, I jacked the port side up and applied brakes with the controller. I could hear it activate. At 1.5 volts I could still turn the wheel somewhat. At 4.5 volts I could not turn the wheel by hand. It sure seems to be that it is working OK on this side.

Please note that the lock-up always occur at slow speed. Application of the brakes at over 20-25 MPH works great, even if aggressive.

One thought is an intermittent short or bad electrical connection. A visual inspection of the wiring reveals no obvious wiring problems but it would not be inconsistent with the other issues I have had related to quality control. The ground connections are typical Scamp quality but is in good shape. I use a Tekonsha P3 Brake Control which has a number of diagnostic features and it does not show any faults. I did think that maybe the voltage was jumping up when the wheel locked, but its hard to drive and watch the controller so I’m not sure about that.

So I guess my next step is to pull the hubs and see what I see. Based on this information, what is your best guess to what is going on?

[Byron Kinnaman]

The wheel that's not locking has a broken wire coming from the brake magnet most likely the one to the trailer frame

[Jack L]

You could have a loose magnet that has worn to the shape of a wedge and when it is energized, it twists and jams between the brake and the drum magnet surface. I had this happen to me. You could also have something else like a broken spring or even a rock causing this. Pull both drums off and inspect the drum and brake system. I solved my problem with new Dexter brake assemblies. In 2012 they cost about $30 per side for standard brakes and for $40 per side I bought the self adjusting assemblies. The self adjusting brakes have worked flawlessly for me. Eastern Marine and Etrailer sell both units.

[sokhapkin]

The trailer's wheels should never lock up. It looks like your brake controller sends too much power to the brakes, reduce it a bit. You will need to adjust the power depending on the trailer's load.

[floyd]

Originally Posted by Jack L

You could have a loose magnet that has worn to the shape of a wedge and when it is energized, it twists and jams between the brake and the drum magnet surface. I had this happen to me. You could also have something else like a broken spring or even a rock causing this. Pull both drums off and inspect the drum and brake system. I solved my problem with new Dexter brake assemblies. In 2012 they cost about $30 per side for standard brakes and for $40 per side I bought the self adjusting assemblies. The self adjusting brakes have worked flawlessly for me. Eastern Marine and Etrailer sell both units.

I think you are onto the solution. There is a cheapo little clip which keeps the magnet positioned on the brake arm. These often break and allow the magnet to have uneven wear or even to jamb.
If you resurface the drums, don't forget the magnet interface surface.

[Raz]

+1 on the magnet. The clips are just pressure fit. As suggested, if the magnet comes loose it will jam things up. Pull the drum. Raz

[gordon2]

OK I get to spend Sunday pulling the hub(s) instead of packing for some camping during the OUTSTANDING weather we expect next week.

I'll report back on what I find.

BTW, if replacement brakes turns out to be the easiest solution I expect that is what I will do, and I like the idea of the self-adjusters. Seems people are happy with them. But it does seem wrong to replace brakes after only 6 months and ~3000 miles. (I'll consider a warranty claim is appropriate also)

[Jack L]

I didn't realize your trailer was so new. If it's the magnet, it should be warranty. Self adjusters are great but the standard ones should hive you many miles of good service too.

[gordon2]

If a picture is worth 1,000 words.. here is 2K worth:

[Raz]

EZ lube!

So is one wheel contaminated?

You said one wheel was locking up. I've never been able to do that with a 7" brake so I assumed that was the bad magnet. Apparently not? Raz

[gordon2]

Originally Posted by Raz

EZ lube!

So is one wheel contaminated? ..

Yes I am pretty sure that is the cause of the problem. There is no visible grease on the pads or the armature but I am sure contamination did occur. So I will be cleaning up the hub, putting a new seal in, and repacking the bearings.

But I am not sure if I need to disassemble the pads and such to get them cleaned up. I would rather not so maybe I can just spray them down good (I just went out and bought two cans of brake clean spray).

----
And I think EZ Lub goes on the same list as Silicone Caulk!

[Raz]

The other wheel locking up is a mystery to me.

[gordon2]

The one locking up is the one in the photos.

[Raz]

Originally Posted by gordon2

The one locking up is the one in the photos.

Then something else is wrong. Why would grease cause it to lock up? Good puzzle

[Carol H]

As other suggest the magnet could well be the issue but it could also be poor ground wire for the brakes. I eventually figured out that was the issue with my 16' as sometimes the brakes worked well and sometimes not well and sometimes too well!!

[gordon2]

Originally Posted by Raz

Then something else is wrong. Why would grease cause it to lock up? Good puzzle

I don't know but some Internet resources say that grease on the works can cause wheels to lockup when braking. Still waiting on more experts to chime in.

And before I get into this too deep, is it normal for the leading pad to stay out after moving the magnet back while the hub is off (simulating brake activation)? Or does it retract OK only if and when the hub is on? No springs seem to be broken but the pad stays out until I give it a good tap. See video.

[Byron Kinnaman]

NOTE: I believe the OP has 16' trailer with 10" brakes.

[Joe Romas]

Looks like the arm the magnet is mounted on is binding at the top where it pivots.
You may also want to apply a tad of grease where the shoes contact the square part.
cure that, adjust the shoes and you should be good to go.
I've been messing all day getting the bearings set just right on my 17' Casita SD.

Joe

[Raz]

Originally Posted by Byron Kinnaman

NOTE: I believe the OP has 16' trailer with 10" brakes.

Thanks, I missed that. No problem locking brakes with a 10" drum. The drum that's not locking is the issue. The grease is just a mess needing clean up. Save the pictures for the next EZ lube discussion.

[Carol H]

Originally Posted by Raz

Save the pictures for the next EZ lube discussion.

Something tells me we will see that photo time and time again for years to come even if the party who took it does not share it again!