Vulcaneer wrote:
I would disagree with some of the info given here. There can be some adjustments done, without needing to bend the axle or the spindle. Before I allowed anyone to re-locate my spring hangers, I would investigate adjusting the spring perch, where the U-bolts mount the axles. If the U-bolts are loosened the axles can be adjusted fore/aft a certain amount. When they mounted your new axles, it is likely they did not mount the new axles in exactly the same location on the springs.
For a tandem axle trailer, the first thing a good alignment shop will do is drop a plumb from the ball socket on the hitch. And mount a laser fixture at the exact center of the front axle. They will shoot the laser toward the plumb. It should land in the center of the plumb. This determines if the axle is perfectly perpendicular to the center of the hitch ball socket. If NOT perpendicular they will loosen to ubolts and jack the axle back and forth until it becomes perpendicular. Then tighten the u-bolts, while watching the laser to be sure it stays where it should be. Then they will measure the rear axle to make sure it is parallel to the front axle. And adjust the u-bolts on the spring perch if needed to ensure alignment. Then they check center distance of the wheels. Must be same on both sides. If not there is a spindle issue. ANd they shoot lasers from the spindles to segregate which one may be out. Then a determination is made whether bending or replacement is the best remedy. Then camber is measured. New axles are bent. That is they way they are built when installed. They need to have a bend in them, to compensate for the weight of the trailer and all the other junk we oput into them. If there is no bend in the axles when we load them down, they would look like this...//=====\\. SO camber is set by measuring and bending the center of the axle to the specified amount. They chain the ends of the axles to floor mount tracks, and jack the center of the axle...while watching the lasers to make sure the right amount of preload is applied. They usually let it relax, for a while, and re-check...so the axle doesn't return by "metal memory".
If an axle, or spindle is not severely bent, it can be re-bent into place and be very servicable for many years. Many will just replace axles. However, even if axles are replaced, they still need alignment. This is what your situation is. You had new axles installed. But they did not align them. And this is why your tires are wearing unevenly. I would not allow anyone just to assume your spring hangars are not located properly. Get a good trailer alignment shop to shoot some lasers for you. A reasonable charge is $200 to put the trailer on the machine to measure the current state of alignment. Then depending on what needs to be done, it could cost another $150 if no new parts are needed. That is adjustments and bending can be done to remedy your alignment.
I agree, nothing should be assumed until measured. The shop I went to was established in 1922, and yes, they use lasers. They are the "go to" shop in the lower Susquehanna valley. I had been advised by Lippert, SunnyBrook, and Stanley Springs (possibly even J Barca, if memory serves)that perches yield very little movement for aligning, (hence Johns most beautiful post on adjustable axle mounts)so moving misaligned spring hangers was the easiest, most bang for buck repair, given that nothing was wrong with my Lippert axles, spindle-wise. As you sound like you know what you're talking about, I assume you understand there is a locating pin which allows very little movement of the axle independant of the perch. Where the spring meets the shackle, so follows the axle within +/- 1/16" per perch. And that's before you retighten the u-bolts. Creep is sure to follow, given manufacturing tolerances. Nothing Lippert makes will ever fly on the shuttle. Just an observation.
When the shop told me they had to move spring hangers, I put my trust in their superior knowledge and experience. They moved them substantially and the results have been nothing less than satifactory so far. Tire wear is not apparent on any of the four and it tracks true.
Your salient point is well-taken, though. Measure and verify before agreeing to any butchery. The problem is where you find it, not where you want it to be. How you get to that point is the tricky part. And all we wanted to do was go camping, right? I didn't plan on becoming a trailer mechanic.
