Electric Brakes on an Enclosed Trailer

[Pulsar]

Just purchased a 3 year old 7x14 dual axle (7k GVW max) enclosed trailer with ramp + side door etc etc.

While driving it home, I used my electric brake controller to actuate the brakes while I was on the freeway. I felt a small tug, but not much. I turned up the controller and tried again. Rinse and repeat until my controller was maxed: I was still getting a very gentle tug when the brakes came on, and after that you'd be hard pressed to tell if they were actually decelerating the vehicle or not.

Now I've driven a 8x24 trailer with electric brakes in the past. If you had the gain turned up all the way and used the squeeze bar all the way over, you'd lock all four wheels up regardless of speed.

To me, that seemed correct: I could adjust the gain on the controller to compensate for the weight in the trailer.

I took the trailer to the local 'good' trailer place. They said one axle was not braking because of a faulty ground wire. After they worked on it, there still wasn't any difference, so I turned around and went right back to them. Their tech showed me how he adjusted the brakes: he jacked one side of the trailer off the ground, and engaged the brakes. Then he tried to turn them by hand. He could just barely turn the wheels, and he said that's exactly how you want them adjusted.

To me that seems insane. I don't expect the trailer brakes to do ALL the braking, but they should at least be doing all the braking for the trailer. The whole point of trailer brakes is so that you're not destroying your vehicles brakes.

They insisted the brakes were adjusted correctly. When applied (at max gain) they prevented the vehicle from moving when it was in drive with no gas applied.

So I'm in a situation where they BARELY slow the trailor+vehicle at all at max gain. Has anyone out there had experience with this? I'd have adjusted them myself but my work schedule doesn't permit it.

Necro-post from a spammer. Closing the thread.

Zenmervolt - AnandTech Moderator

 

[SparkyJJO]

I've never towed a trailer, much less one with electric brakes, but it strikes me as the trailer brakes are just an assist, not major braking power. I wouldn't think you'd want the brakes on the trailer to yank on the vehicle towing it.

 

[SooperDave]

IMO trailer brakes are helpers. Big helpers to be sure but when you look at the size of the shoes (and the fact they are shoes not pads) vs. the weight you need to stop it would seem to reason they can't stop under a full load as fast as the tow vehicle will stop. Unloaded my utility trailers have been able to lock up the brakes. Loaded not so much.

 

[SooperDave]

What the shop did doesn't sound right. With everything at max he should not have been able to turn it by hand. If you don't have the time to adjust the mechanical adjusters at the base of the shoes yourself take it to another shop. Or even just call another shop and see what they say about the way it stops. Leave out the part about having been somewhere else first. It's not relevant and sometimes you get a place that will bad mouth the competion just to get your business.

 

[Pulsar]

I've never towed a trailer, much less one with electric brakes, but it strikes me as the trailer brakes are just an assist, not major braking power. I wouldn't think you'd want the brakes on the trailer to yank on the vehicle towing it.

Sparky, you're absolutely right. However, you also need to account for different trailer weights. If, with the trailer empty and the gain maxed you can't even get the wheels to lock up on gravel or really slow the stuff down, when the thing is 7000 lbs rather than 2500 base weight, you're going to have a 4500 lb trailer basically living on your vehicle brakes.

I had that happen when my surge brakes failed coming out the mountains in the Carolinas with my boat, and I overheated my transmission (using the transmission to brake by downshifting) AND glassed the brakes trying to keep the trailer under 80 mph.

That's what the brake controller is for - you can adjust the gain based on your vehicle weight. It just doesn't seem right that at max gain the thing has almost no effect on an empty trailer and truck.

Sooper - thanks. I've already got a list of places to call tomorrow. Advice should be free, right? =).

 

[herm0016]

i tow trailers with up to 8 to 10k on them all the time for work, they are large construction type trailers that have regular dot inspections from our mechanics who are cert. to do these things. the brakes should stop you at idle or a small amount of throttle, the breaks should not stop you on the freeway. they will help you stop, but should not stop the entire vehicle. ofcourse this is with the trailer loaded.

 

[Greenman]

Sounds like the trailer brakes are out of adjustment or the controller has gone bad. Adjusting the brakes is pretty easy with a break spoon, tighten until they just make contact, then back off a half turn. On my controller, the override will only put out the max power it's set at. According to the instructions, the control is adjusted properly when you can lock the trailer wheels at 25mph using the override. This is on a very good quality progressive control.

Edit: My control also has a boost button to allow for worn brakes.

 

[Zenmervolt]

Every time I've towed an empty trailer with electric brakes, it'll lock 'em up if you forget to turn the gain back down from whatever you were towing before.

I agree with what people are saying about how the trailer brakes shouldn't be able to stop the entire combination with any sort of rapidity, but that's what the adjustment is for. If you leave the gain turned up all the way on an empty trailer, it should easily lock the wheels on the trailer.

ZV