Tire ,alignment

BettyToo wrote:


I've been under and measured the axel with a straight edge, it appears ok, a slight upwards curve, which I believe is correct. I have also measured the Toe in and that's about 3/8". So question is (other than 4 new tires) what should I be looking for with regard to camber on the front and rear and what should the toe in be? Is 3/8s too much? Is this what's causing the outside wear? Any help advice greatly appreciated.
Thanks all...

Hi,

I ran into a situation back in 2008 on my camper. After much investigation I found the problem and corrected it. I had 2 axles made with the wrong toe angle from day 1, (created excessive toe out) I had a front leaf spring hanger welded on wrong from day 1, (created thrust angle issues) and the rear axle hanger was welded on wrong too. (created the front and rear axle to not be parallel).

This post shows how I backed into finding the problem and by how much things where off
Tire Wear Pattern-Tandem Axle TT (Pic's) Where to look next

The correction started with creating adjustable axle seats to properly align the front axle to the tow ball, and then align the rear axle parallel to the front axle. Then 2 new axle tubes within spec where installed. I was able to hit the alignment numbers declared by Dexter. The system has now tracked and wears tires even now ever since. You can measure the tire wear across the face of the tire and it tells a story to what that wheel is doing. However there are a few ways that wear can be created. This post was the correction. It also lists the alignment specs I found. The toe spec is in degrees of angle. You will have to do the math to convert your 3/8" measurement back to degrees. You did not say how and where you measured that, but 3/8" is a real big number.
TT axle alignment & install - Detailed (long lot's of pics)

There is a lot of detail in there that may help you. And you can see what you will be up against and if your home shop can accommodate it. If you can't, you need to find a trailer alignment shop that works on trailers. It does not have to be an RV dealer, as I myself could not find an RV dealer in my area that had the alignment equipment to even verify the problem. They just change parts sent by the camper mfg. Shops that work on semi trailers do this kind of work too. And there are some shops that can bend the axles tubes to create proper alignment. I did not want to go the bend a tube way, I just bought new axle tubes.

Hope this helps

John

There are six elements to the alignment of four wheels on a dual axle trailer: 1) are the axles perpendicular to the center-line of the trailer; 2) are the axles parallel with each other; 3 - 6) toe, caster and camber on each wheel. Any Hunter-equipped truck and trailer shop (as in big rigs) can measure all this. Unfortunately, the only things that can be adjusted on solid-axle trailers are numbers 1 and 2. If there are alignment issues with any individual wheel, there is a bent axle or spindle - either of which usually require replacement of the axle and realignment. From personal experience and the advice of professionals, a tape measure and straight edges may get you close enough for a few short trips every year, but it takes more sophisticated equipment for a complete and accurate alignment. As Don says, the plastic bushings found on most trailers are very soft and wear out quickly. Check all the things mentioned above (spring mounts, shackles, bolts, bushings, etc.), put on the new tires and watch them very closely for any signs of unusual wear. If it recurs, "seek professional help."

Rob

3/8 is too much. I don't know how the tow in could increase. If you hit anything going forward. it would decrease if anything. Maybe you didn't check it accurately ?
But all in all, if your tires got too old before the tread is gone, you may not need anything done.

Thought that 3/8 maybe. May have to get a guy out to check the alignment then.

E-trailer.com has videos on bushing replacement and parts or Amazon for parts and Youtube for video.

3/8" seems like a lot of toe in and may explain the wear on the outer edge.
Camber? Tire should be vertical when loaded.

Really need a tire picture. Are remaining tires flat across the tread? Bulged out at all or unevenly could be a slipped belt.

Off to the RV Shop then....!

Not out of the realm of the average weekend mechanic. Buy a complete wet bolt kit and plan a weekend. Hardest part is supporting the RV, then taking stuff apart and getting it back together. Lots of jacks, some pry bars and basic hand tools plus a torque wrench to torque the shaxkle bolts.

Thanks for that. 4 new tires definitely happening. I'll take a look at the bushings too. Are they an easy fix?

Install new tires and have the alignment checked andmfixed as necessary. While your at it inspect spring eyes for wear. The plastic bushings found on most trailer syspensions are only good for maybe 5 thousand miles before there worn out and start eating up the spring eyes.