Alignment spec on 2 axle trailer

[TheTichenors]

I have a 2020 Surveyor 272FLS with 4400 lb axles. The front axle is perfectly aligned with the hitch. However, the rear axle is not parallel to the front axle. One side is 3/8" off. This variance is confirmed at the frame hangers.
My dealer service tech says this is within spec from the frame manufacture.

Is it?

[SeaDog]

You best bet would be to contact the frame mfg and get the actual specs from them.

[Lins]

As in it's off to one side? As long as it's square you shouldn't have any tire wear issues. I agree with SeaDog, check with frame manufacturer. If they say it's within spec, just make sure it's square and don't worry about it.

[Mike134]

If there is a difference of 3/8" between the 2 axles no way they are square to each other or the trailer coupler. Judging from the Op's comments the front axle is square to the coupler the rear axle is crabbing 3/8" in one direction.
I have no idea of the specs for a TT but you would never find that large of an allowance on an auto.

[TitanMike]

Originally Posted by Mike134

If there is a difference of 3/8" between the 2 axles no way they are square to each other or the trailer coupler. Judging from the Op's comments the front axle is square to the coupler the rear axle is crabbing 3/8" in one direction.
I have no idea of the specs for a TT but you would never find that large of an allowance on an auto.

That will all depend on what the actual toe readings are on the mentioned axle. If one side is toed in and other is toed out but in relation to the centerline of the vehicle the toe angle is equal, there will be no tracking error (if amount of toe in/out is correct. It wasn't until about 1981 that the concept of Thrust Angle Alignment, where all wheels are aligned to the centerline of the vehicle became easy as new instruments were introduced. Before that it was all chalk lines, tape measures, plumb bobs and marks on the floor, not to mention hours of labor.

I spent years explaining and demonstrating this to even old experienced mechanics. Without proper measuring tools (instruments) you can't rely on merely tape measure differences. What's happening where the tire tread rolls on the road is all that matters.

[Palinduff]

Any alignment or axle questions I’ve ever had with a dealer I was told to go to an axle / spring shop. That’s where they would send it anyways; so avoid the middle man. I appreciated that advice.

[Scrapper]

Sprung axles shift when turning so couldn't the 3/8" difference be caused by not being in a straight line.

[TitanMike]

Originally Posted by Scrapper

Sprung axles shift when turning so couldn't the 3/8" difference be caused by not being in a straight line.

Because the springs are semi elliptic the axles can move if one axle is loaded more than the other on one side. As the curve in the spring is straightened between fixed pivot point it effectively gets longer. This will cause axle to shift forward or back depending on whether it's a front or rear axle. Front's will move back and rears will move forward.

When tandem axle alignment is checked it's supposed to be on a flat, level, surface and after the trailer has been moved in a straight line to allow axles to relieve any stress or shift due to turning. This can also be done through the use of "Slip Plates" under each wheel which are merely plates supported on ball bearings that allow the wheel to shift in all directions and relieve any stress that would cause false readings.

That's if it's being done properly.