trailer brakes locking up/ hopping

hi, i have trailer and when it's empty trailer brakes lock up (hooping, if you know what i mean) even when you push on them very slightly. Over the years i have had few of these trailers behaving like this but cant' figure out what the problem is. Brakes are new, so that's not the problem. also i think it's only happening on front axle since tires on that axle wear faster and uneven/bold spots. Any help will be appreciated. Thank you

 

Service control valve on trailer is bad

 

Seen a logging trailer do that. I think it was because the guy welded new cam tubes and brackets on but they were not parallel to the axle (up/down and fore/aft were really crooked). Caused uneven wear on the shoes. (Like 1 shoe worn out and the other not even touched). Maybe check cam tubes to see if they are straight.

 

any idea how much do they go for, trailer is 04 great dane dry van

 

I am not sure exactly but I think around 150. I would have a shop check it out first to make sure what it is . May be cheaper in long run.

 

Is it worse in rain? Mine used to do this. Was an abs issue. Did not have power to center pin on electrical cord.

 

I am having problem with my trailer. it's 2014 utility 4000dx dry van . I have 2S/1M basic setup under trailer. The ABS valve is Bendix TABS-6 Basic. Only rear axle has sensors . When rain or empty/light load front axle's wheels lockup(only front axle). No fault codes, no service light on. All brakes are properly adjusted, air bags are inflated and ride height is ok. Slack adjusters are automatic and no way to keep them a little loose. Was at dealer and they did not figure out why it happens . My friends suggest me to spend $1000 and get 4S/2M Wabco setup.
what do you think guys? what else I need to check ?

 

Does it have a Hendrickson suspension with SURELOK? This has to be the single most tire ruining invention to ever come out.

Here's what happens...

The locks (on the rear axle) fail to apply quickly enough and miss the pads, allowing the suspension to fully bottom out. This, in turn, bends the lower mounting bracket for the leveling rod because it is not designed with enough travel.

The next time the suspension airs up, the ride height is a tad too low for the locks to engage at all.

Then, one day you'll set the trailer brakes on uneven ground and the rear axle will be low enough to engage the locks. When you release the brakes, pull the trailer out and hit level ground, the leveling valve sees the suspension is too high and won't air up to release the locks.

The first thing you notice is the trailer rides really rough like an old spring ride. The you go to lightly apply the brakes and the tires on the front axle will skid and hop because the suspension has no air in it. The trailer is sitting completely on those solid bars on the rear axle.

Before you go spending money on brake valves or ABS, make sure that's not what it is.

 

it's Hendrickson suspension without surelok.

 

I would take it to a scale when it's empty and split the rear axles to weigh them individually. See if the rear axle is lifting the front one off the ground slightly.

Edit: The whole truck needs to be level and on the scale when you do this. Put it on the scale backwards and use the steer and drive platforms if you have to.