Abnormal trailer tire wear... torsion axle rebuild?

To the best of my knowledge, I've only ever owned two torsion axle trailers.  The first one I didn't own long enough to ever need tires, but it did show cupping on the tread.  In defense of the trailer, I had overloaded it considerably.  My current boat trailer has torsion axles and I know it's not overloaded.  It's a 3500-lb axle.  The boat is likely 2300 lbs and the trailer is all aluminum and probably weighs 750 lbs.  I'm getting significant cupping and abnormal wear on the inside of the tread and wondered if this is when people suggest "rebuild the axle."

I assume that means replacing the rubber "spring" inside?  

Is there any alignment possible with that type of suspension?   If not, I could see how worn parts would allow the tires to be dragged down the road out of alignment and wear tires poorly.

In reply to Curtis73 (Forum Supporter) :

I suspect that it is an alignment issue from that wheel  clipping  a curb causing a twist or slight bend on that end of axle. My experience with torsion axles is that they are more prone to this happening. We had one company trailer that would shred the tire on one edge in little time until that side of axle was replaced. No adjustments were possible on it to compensate for the twist on that unit. Quick alignment check should show.

Every overloaded torsion axle I have ever dealt with eats tires. I think the rubber can't keep the tire in allignment when it is overloaded. 

This is why all of my trailers run springs. 

Replacing the torsion assemblies with new ones capable of handling the weight will probably fix it. 

In reply to Toyman01 + Sized and :

This one isn't a weight issue.  3500 lb axle with about 3000 on it.

Edit:  Any of my tandem axle trailers are spring axles.  The wishbones between the springs really help to keep equal weight on all 4 tires.  Tandems with torsion (which I've also had) you have to be really careful to have a level trailer or you risk putting a lot more weight on the axle that is compressed more.  My previous torsion trailer was that way and I was constantly checking tire temps and it didn't take much of an imbalance to make one axle's tires notably hotter.  

I would like to keep a torsion axle under this one for the ride quality.  I think the boat rides smoother on the trailer than it does on the water.  It would also be a bit difficult to fab up a spring axle setup, mostly because the frame is aluminum I-beam.  I'm sure it can be done, but the way the trailer is engineered, it really should have a full-width tube/torsion.  I have a feeling that adding springs would be a level of fab that I would rather not take on.

I will check alignment on it.  I doubt alignment can be fixed on this one.  If they were just stubs bolted to the frame I could change it pretty easily, but this is a full-width tube.  I suppose bending the tube is a possibility, but a brand new complete torsion axle isn't prohibitively expensive, so maybe not worth the hassle.

In reply to Curtis73 (Forum Supporter) :

Even at max loading or close to it the torsion axles I've dealt with seem to eat the inside edge of tires. It seems that as the torsions rotate they toe out. 

The local SCCA autocross group have this problem with their equipment trailer. The only thing that seems to solve the issue is getting weight out of the trailer. 

My brother has a similar issue with his boat trailer. We considered mounting two axles to reduce the load. Without equalizers that wouldn't work very well. He switched to radial car tires and it helped some. Car tires are frequently cheaper than trailer tires so he would buy new ones every 3rd year or so.

I got some radial trailer tires to put on but I need to check what's going on first before I tear them up too.

There are torsion "stub" axles too which just bolt to the frame but are not connected to each other. If you have those it seems one could be out of alignment pretty easy.

In reply to Robbie (Forum Supporter) :

Mine is a full-width tube, mostly because the frame is aluminum.  That way the axle can just bolt on with some u-bolts as opposed to drilling the flexible aluminum.  I think if I just drilled the aluminum and put stubs on it, the aluminum would twist and flex causing camber (and stressing the aluminum).  The full-width axle is kinda needed so it's sort of its own subframe and just supports the aluminum instead of using the aluminum as the support.

It's entirely possible that the tube could be bent to correct any toe issues, but if the axle is allowing toe-out from flexing the rubber inside the tube, it might only show up while driving.  I could set zero toe in the driveway, but will it be zero toe at 65mph?  Who knows.

Yeah I missed that full width part. Could also be "bump steer" ie when loaded the wheel steers. I don't have any experience but I've read that many people flip torsion axles to get lower trailers but it messes with the bump alignment. That's probably not your issue but easy to check.

I'm not sure you can rebuild those springs. Might be time for a new axle. Maybe also check for bearing play first? Doesn't seem like there's too much to be going wrong.

Toyman01 + Sized and said:

In reply to Curtis73 (Forum Supporter) :

Even at max loading or close to it the torsion axles I've dealt with seem to eat the inside edge of tires. It seems that as the torsions rotate they toe out. 

The local SCCA autocross group have this problem with their equipment trailer. The only thing that seems to solve the issue is getting weight out of the trailer. 

My brother has a similar issue with his boat trailer. We considered mounting two axles to reduce the load. Without equalizers that wouldn't work very well. He switched to radial car tires and it helped some. Car tires are frequently cheaper than trailer tires so he would buy new ones every 3rd year or so.

 

Yup, same deal here with my torsion trailer. If Im mostly towing a lighter car around for the season, tire wear isnt bad. For the 2 seasons I towed a car twice as heavy (but still well within rated trailer weight), the inside tires would eat themselves very quickly. 

The only torsion axles I've had experience were under Airstreams; my 1966 21' was a single axle, and was towed all over the S. E. , loaded above the trailer data plate weight. No problems with abnormal tire wear, and I'm sure the average person would have suggested a rebuild, considering the age and miles on the torsion rubber! But I have no clue what the axle itself might have been rated for... Airstream may have over built that, and underrated the data plate!

Same for my 1977 26' tandem; I did keep the load leveled between axles, but lotta weight, and no abnormal wear. 
That all being said, with 3000 on a 3500 axle, I'd recommend a slightly heavier axle, since I think the others experiences are probably more accurate. The physics of it make sense to me. 

Any local alignment and suspension shops that work on medium/heavy duty trucks? It might be worth check to see if they can align it with the boat on it.

That way it will be adjusted for the loaded conditions and any vertical/rotational deflection in the axle can be compensated for statically. There may also be opportunities for some additional toe in to compensate for deflection when moving

In reply to 03Panther :

Agreed on the beefier axle, but the next step is 5200 lb, and I'm afraid it will ride rougher than a proper spring axle.

I'm also not finding any torsion full axles.  Makes me wonder if manufacturers weld their own tube in the middle when they do a full-width torsion.... which I could do I suppose, just get two torsion stubs and use something like a long piece of angle iron to jig it up.

I suppose I could do two 2200-lb torsion axles and just be really careful about leveling.

It also makes me wonder why no one has come up with an equalizing system for tandem torsion axles.  Like if the two axles could be mounted to a plate with one pivot in the middle

In reply to No Time :

Plenty of truck shops around here, but it may be academic.  If I set zero toe while sitting still and the drag from the tires causes it to toe-out at 65mph, I will have accomplished nothing

Pics if you're curious.  The bottom of the aluminum frame rail has a T-track that you slip 1/2" bolts into so the whole thing is kind of like an 8020 extrusion

Curtis73 (Forum Supporter) said:

In reply to No Time :

Plenty of truck shops around here, but it may be academic.  If I set zero toe while sitting still and the drag from the tires causes it to toe-out at 65mph, I will have accomplished nothing

Exactly.

That's why I mention opportunity for additional toe-in, where drawing upon their experience to help set a proper toe-in so that under a load the movement does not create toe out. 

The other aspect is that as the torsion axle deflect under load the toe may change from empty to loaded, so aligning under load will compensate for static deflect just due to the movement of the axles under normal loaded condition. 

I get what you're saying, but I don't think it's practical to guess how much toe.  I can measure toe loaded and unloaded, but I can't measure it at 65 mph where drag might be causing additional toe.  Re-setting toe sitting still means I'm guessing.

I'm going to try measuring toe weighted and not weighted to see if it's different.  If I find a difference I could also assume a bent spindle (which is replaceable).  If I don't see a difference and it's zero toe, I suppose I can assume that it's the rubber failing and allowing toe from drag?  He says with a question mark?

NOT the GRM solution, but I bet it would "fix" the problem 

http://Airstream axle…