Electric trailer brakes

[Kennedy]

I recently took on a project to help a local woman. She has a 2000 F250 and a 4 star gooseneck aluminum horse trailer with 3500# axles. She has had issues with locking up brakes and destroying tires. I can into the project after much of the work had been done. I believe that the initial issue may have been broken wires and only 2 brakes working, but by the time I worked on it the brakes were all new. In my experience, electric brakes tend to be on the weak side and the only time they really grab is when they are adjusted too loose and the actuator arms start to "wedge" in. These were just plain nasty aggressive and my initial at speed testing was VERY rough on her tires.

Here is my report to the owner.

Trailer:
All 4 brakes have had recent complete brake assemblies installed by Dave S. They are Axle-tek brand aftermarket and are in like new condition. Drums showed no ridge. One hub was found to be cracked so it was replaced. This was the LH rear and appeared to have been very hot at one point prior. Road testing found the brakes to be far too aggressive when adjusted snug as is the common practice. I removed the auto adjust hardware from all four brakes. Auto-adjust hardware is just not a good thing to have. They tend to adjust the brakes up too tight whenever you back up. I adjusted snug then backed off approximately 12 clicks. I then worked through the brake adjustment by applying brakes manually at level 4 and identifying which wheels would skid from a standing start. When one would skid I backed off adjustment several clicks at a time until the wheel would no longer skid. I then worked controller level up to higher settings and continued to back off wheels that skidded. This level of slack is not what I would deem to be normal, but it is apparently what is necessary to keep them from skidding. I ended up at a point where I could run the controller at the max level of 14 with no skid. I then started by giving a few clicks tighter and had locking at level 6 again. Setting controller to 5 seems pretty safe and has good braking capabilities. This may change as brakes get more effective when warm. I can revisit in better conditions. To me it seems that the lining material just wants to dig in exceptionally hard making it difficult to find a happy medium.

Removed 6 way lighting connector and adapter plug from trailer and changed the trailer cord to 7 way connector to fit the truck directly. Replaced trailer safety breakaway system with new unit that includes an automatic charger. The charger wire is tapped into the clearance lights so every time clearance lights are on the breakaway battery will receive a maintenance charge.

Replaced left rear hub and drum assembly due to crack in the hub. The grease in this unit is Lucas brand red and tacky. Others are a black grease.

[Kennedy]

Electric trailer brakes are nothing new to me. My way of adjusting follows conventional wisdom which is to crank up until the wheel would not turn then back off to a very slight drag. Dirt simple, consistent, and always worked.

For some reason these want to almost "wedge in" tight. Not sure if it's the lining material or what? I seem to recall the genuine Dexter material being a yellow/goldenrod color organic type. These seem like a semi metallic type.

[JohnC]

How'd you get the horses to stand in there that long? ;)

[sctrailrider]

I've had somewhat same results from off brand linings..


What controller was this with?

[Kennedy]

I've had somewhat same results from off brand linings..


What controller was this with?

She had a Draw Tite activator. It was set with the synch to full fast and output to level to 2. I replaced with a Tekonsha P3 for versatility. When Draw Tite first came out with these I thought they were great. Never really liked the mercury level switch in the Tekonsha. Once the Prodigy came out and I tried it I never looked back.

I did test the Draw Tite controller hooked to my trailer (stationary) and found that it modulated the output just fine. I did not do this with either controller hooked to the problem trailer. I think I will in spring, but we've been battling snow and I can't get the truck and trailer together inside.

I know that the trailer plug end is good because I rewired from a 6 pin with adapter to direct 7 myself. I ohmed for cross connections and found none. Magnets all ohmed at 2.8-2.9ohms. Ground potential from the brake wires .3 ohms more or less.

[JohnC]

I don't suppose it could have been a leading/trailing brake shoe issue, could it?

[Kennedy]

Well the vehicle owner has cancelled her trip plans for now although she'd have been fine as it is. I will take another look at it when the weather clears up a bit.

[DickWells]

Good post, John. Confirms everything that I've learned over the past many years. I don't ever remember using anything but Dexter, and your "standard" adjustment is just what I've always used. Every time I've had issues with unequal braking, it's been a matter of too-loose adjustment on one wheel, or another. But, your mention of wedging, or camming-over brings back some ugly memories!
Thanks:)

[cowboywildbill]

I've seen this when the leading trailing shoes were put on backwards.
You've got'a love electric "Shoe" brakes ! Seems like they don't have enough braking power on big heavy trailers, and too much on small lighter trailers.
I know it's a cost issue and also that some brake controllers don't work without modification on the disk brake systems, but disk are the way to go on big stuff.