Electric Brakes Not Releasing

manyman297 · July 22

2021 400. Just repacked the bearings this spring and finally got it out on the road this weekend. Things were fine until I was at a stop light and squeezed the brake controller manual lever just to test it. Upon letting off the truck’s brakes the vehicle didn’t creep forward as it always does when I release the brakes.

As I accelerated I could feel resistance. Pulled over, disconnected the 7-pin thinking it was an electrical issue. Plugged it back in and still felt it dragging. Finally I decided to back up a few feet….this did the trick and all was well. Several miles down the road I could tell the brakes were grabbing again as I was going downhill but losing speed when I let off the gas.

Pulled out the temp gun and the passenger side drum was 210 and the driver side was 144. So something isn’t releasing and it doesn’t seem to be electrical in nature. Anybody else have an issue like this? I read that maybe the return springs in the drum mechanism could be the culprit?

Bayliss · July 23

@manyman297, I do not have a specific answer, but you indicated that it does not seem to be an electrical issue, so I am just throwing out the below question as a possibility (which would be an electrical issue.)

You did not mention it in your post, but have you checked to confirm that the emergency breakaway/brakes controller pin is properly secured? If the switch is activated (pin pulled out), that would make an electrical connection between the trailer battery and the electric brakes. (Other parts of your post tend to be inconsistent with that possibility, such as backing up and the brakes apparently disengaging for a period of time, so this is a "just in case" response.)

pthomas745 · July 23

Frayed brake wire?

https://tab-rv.vanillacommunity.com/discussion/13863/frayed-brake-wire-on-2021-400-bd

Grumpy_G · July 23

@Bayliss already suggested an easy thing to check. Otherwise I'd think the brakes are adjusted too tight. Drum brakes are typically "self-energizing" (actually self-servo) meaning the front (leading) shoe pushes the rear shoe against the drum. The front shoe doesn't require a lot of pressure against the drum to create a lot higher braking force at the rear shoe.

Did you change the adjustment of the brakes to remove and reinstall the brake drums ? The brake shoes are sort of floating so you might have to remove the drums again and check if anything is askew.

manyman297 · July 23

Bayliss said:

@manyman297, I do not have a specific answer, but you indicated that it does not seem to be an electrical issue, so I am just throwing out the below question as a possibility (which would be an electrical issue.)

You did not mention it in your post, but have you checked to confirm that the emergency breakaway/brakes controller pin is properly secured? If the switch is activated (pin pulled out), that would make an electrical connection between the trailer battery and the electric brakes. (Other parts of your post tend to be inconsistent with that possibility, such as backing up and the brakes apparently disengaging for a period of time, so this is a "just in case" response.)

Yeah, I checked the breakaway cable but I don’t believe that to be the cause. Backing up worked that one time. I tried it again later in the trip and it didn’t work.

manyman297 · July 23

pthomas745 said:

Frayed brake wire?
https://tab-rv.vanillacommunity.com/discussion/13863/frayed-brake-wire-on-2021-400-bd

Funny you post that since it’s my post

After that incident I religiously check those wires. I also think this issue is mechanical and not related to any electrical problems.

manyman297 · July 23

Grumpy_G said:

@Bayliss already suggested an easy thing to check. Otherwise I'd think the brakes are adjusted too tight. Drum brakes are typically "self-energizing" (actually self-servo) meaning the front (leading) shoe pushes the rear shoe against the drum. The front shoe doesn't require a lot of pressure against the drum to create a lot higher braking force at the rear shoe.
Did you change the adjustment of the brakes to remove and reinstall the brake drums ? The brake shoes are sort of floating so you might have to remove the drums again and check if anything is askew.

I did notice the passenger hub was much harder to break free when packing the bearings. Almost like the shoes were slightly engaged still. I don’t recall them being like this the last time I repacked but that was some time ago.

If they were too tight I’d constantly be feeling this drag and my brakes would have probably overheated at this point. Plus backing up somehow released the shoes in some way.

What’s odd is that I test drove the camper around town and on the highway last week and everything was fine. Temp on both hubs was within 10% of each other.

I need to check the adjustment on the passenger side when I get a chance. I need to figure this out before our next trip in a few weeks.

pthomas745 · July 23

@manyman297 Yes, funny how those things work sometimes.

The "frayed brake wire" info you gave has helped plenty of other owners with that same issue.

Horigan · July 23

I would pull the drum off and inspect the mechanism looking for areas that may be corroded or sticking. If this is new behavior, I wouldn’t address by loosening the shoes.

manyman297 · August 6

Quick update on this issue. So far I’ve double-checked any connections, contact points and pivot points. Lubed whatever I could and have gone so far as to run a propane torch, brake cleaner and sand paper to both sides’ brake shoes to rule out any possibility of contamination. Adjusted brakes once again.

Upon initial test drive I thought I had fixed it. No brake grabbing at all. Once I got on the highway, back off and checked the brake temps I noticed the same grabby at low speeds, locking up behavior. Again, if I back up slightly this seems to release the shoes and I can drive freely but if I put any sort of force on the brakes (1.2v and up on the controller) the brakes will begin to drag. At one point my hub temps were 250 degrees (normally are around 150).

I’m at a loss. I can put new shoes in but I have no idea if that really is my problem. BOTH wheels seems to be exhibiting this behavior which led me to believe that me leaving the drums off for a couple of weeks back in February to pack bearings led to contamination of the shoes somehow.

Also, I don’t believe this is an electrical issue at all. Brakes will remain locked up without power to them. I even tested the breakaway cable. If I pull it the brakes lock up as they should. When I insert the breakaway back in it requires a bit of effort to rotate the wheel forward with my hands until it eventually “breaks free” and I can spin it.

manyman297 · August 7

Below is a link to a video of what I originally thought was happening. You’ll see that the actuator arm has some play in it and when the brakes are applied I thought that maybe it was getting hung up on that corner.

Now I’m pretty sure this isn’t the case as the wheels would completely lock up if this were the case and I can’t see the actuator arm moving that much as the distance between the shoes and linings are like 1mm of distance.

Also, both wheels are exhibiting this behavior so any mechanical failure would have to be identical and happen at the same time…not likely.

I’m still thinking some kind of contamination happened when I had the drums off for a couple of weeks back in February.

Link:
https://imgur.com/a/2eEc7pU

TourDeForth · August 7

Just curious, have you tried towing it without using the brake controller? To be more specific try towing it without using any brakes. Just a dumb trailer. Then see if the brakes heat up or set without any input. This would rule out any mechanical issues like components slipping, misalignments or parts moving etc. if they stay cool, then you have narrowed it down to a brake application event. I know that won’t tell you much but it does provide some more information…

Bayliss · August 7

@manyman297, is it possible that the spring behind the magnet is malfunctioning, thus causing the actuator arm to pivot, but not release, thus causing the brakes to lock up?

I thought about this after watching your video and seeing the actuator arm getting hung up until you push it back to its normal position. Maybe when you back up the trailer, that is enough to push the magnet back, but eventually it is possible that it will again push outward toward the brake drum.

This is a good video that talks about the magnet operation and the spring behind it. Worth watching, if nothing else for the helpful information it provides:

https://www.youtube.com/watch?v=ZEJ2DUdMhE8

After posting the above, I came across this video, which shows what a bad spring looks like:

https://www.youtube.com/shorts/JIKy4WO0oaU

manyman297 · August 7

TourDeForth said:

Just curious, have you tried towing it without using the brake controller? To be more specific try towing it without using any brakes. Just a dumb trailer. Then see if the brakes heat up or set without any input. This would rule out any mechanical issues like components slipping, misalignments or parts moving etc. if they stay cool, then you have narrowed it down to a brake application event. I know that won’t tell you much but it does provide some more information…

I haven’t but I do know that activating the brakes is what causes them to hang/stick. I know that doesn’t necessarily rule out that they engage on their own but the problem seems to always happen if I engage the brake more than 1.2v on the brake controller. And that’s not always the case. I can surpass this voltage and the brakes release just fine. No rhyme or reason.

manyman297 · August 7

Bayliss said:

@manyman297, is it possible that the spring behind the magnet is malfunctioning, thus causing the actuator arm to pivot, but not release, thus causing the brakes to lock up?

I thought about this after watching your video and seeing the actuator arm getting hung up until you push it back to its normal position. Maybe when you back up the trailer, that is enough to push the magnet back, but eventually it is possible that it will again push outward toward the brake drum.

This is a good video that talks about the magnet operation and the spring behind it. Worth watching, if nothing else for the helpful information it provides:

https://www.youtube.com/watch?v=ZEJ2DUdMhE8

After posting the above, I came across this video, which shows what a bad spring looks like:

https://www.youtube.com/shorts/JIKy4WO0oaU

I did check the play on the magnet. It moves smoothly in and out. Hard to tell from that video you linked to as to what the bad spring is doing though.

Again, this is happening on BOTH wheels. That’s not to say components on both sides can fail simultaneously but it’s doubtful.

I’ve taken a propane torch, brake cleaner and sand paper to all shoes just to make sure ther are no contaminants but maybe that wasn’t enough.

One important thing I should mention is that I can engage the breakway cable to get the drums to brake at 12v power. From there I’ll reinsert the cable and go to the wheels and I can barely nudge them backwards and they’ll release (no clunk sound or anything alarming). If I force them forward they’ll be difficult to spin but eventually they’ll break free and spin normally. Again, no clunking sounds as if the actuator arm was hung up and released. This is why I feel like the problem is in the shoes themselves. Return springs come to mind but BOTH going out at the same time?

manyman297 · August 12

Quick update. I've ordered two new brake assemblies to rule out any further issues with the current setup. My question to those who might know:

My drums are in decent shape. I was hoping to find a shop that would turn them but I'm having trouble with that. The two shops I talked to said they just replace them as that is more cost effective. The problem I'm having is the Dexter drums for the 400 are rated at 4k lbs. when most other 10" brake assemblies are rated at 3.5k lbs. and are MUCH cheaper. New Dexter drums are $210 each which is out of the question. Are there aftermarket options I'm just not seeing?

Mickerly · August 13

There is another company that makes replacement parts for the Dexter brakes. I've tried them. Stay with the Dexter parts.

Maxcamp · August 13

Frustrating. After splicing our frayed brake wire we spent two years fighting with mismatched braking and pulling. Nothing rectified it until we replaced brake assemblies, drums, and pulled all new wires to rule out resistance differences.
Sorry you're dealing with this.

manyman297 · August 13

@Maxcamp Yes, we’ve also dealt with braking issues since day 1. The main one is uneven braking (hot passenger wheel) which was mostly rectified by tightening the driver brake adjustment slightly tighter. The quality of these brakes just feels like junk to me compared to what you get on passenger vehicles. They’re crude in comparison.

I’m really hoping these new assemblies solve the problem.

Maxcamp · August 13

After doing the camper over two years ago I also fully rebuilt and rewired the Dexter axles on my two construction trailers. Monitoring with heat gun, no issues. No side pull and there's a lot of weight at times.
What's different with the Nucamp other than shoddy workmanship and dangerously deficient wiring? Flimsy frame? Not sure that would twist the axle enough to change brake to hub alignment.
A puzzle.

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