Unusual rear tire wear

[St Runner]

My 97 runner has been getting uneven tire wear on my rear tires, more on the inside of both tires than the outside Backstory is the complete rear housing with locker I pulled off a 97 limited and swapped in. In my usual haphazard way i just used whatever bushings looked best on the control arms figuring they were all the same. The limited I pulled the axle housing from was damaged slightly from running off the road but not from collision. No vibration, rear seals are original and don't leak. It never handled particularly well since I changed out the rear axle but I thought it might be the spacer on the 906 springs and the raising of the rear swaybar to miss the locker. I have a complete axle assembly on my 98 parts runner which i can modify to fit the locker and 4.30 gears My question to those with the knowhow is are there any conditions under which the geometry being off will cause these wear conditions? Both sides are wearing the same with more tread coming off the inside (closer to the diff) than the outside. Locker is working correctly with one tire spinning unlocked and both spinning locked

 

[clearock]

I'd check the camber on ur next alignment sheet, sounds like ur housing could be bent...

 

[St Runner]

I think the housing is bent too. I just don't know if having the axle aligned improperly would cause that kind of wear.. Both sides are equal in uneven wear. I will talk to my local guy with the alignment machine

 

[gamefreakgc]

From my understanding of alignments, most shops don't really touch the back end. I think you'll need to specifically ask if they can measure the angles and if they are in spec, and then if they can be corrected.

 

[St Runner]

I went and talked to them this afternoon, he said it can be programed to do the rear he just needs to go through and figure out the programming because it is not done often. He also said that poor bushings esp on the trackbar will cause it to give unusual wear patterns. So my next step before I bring it in is to go through all the bushing and check them carefully. I might just replace the trackbar (the one that goes from the upper frame to the axle if I am naming it correctly) with the one on my parts car

 

[Bad Luck]

I went and talked to them this afternoon, he said it can be programed to do the rear he just needs to go through and figure out the programming because it is not done often. He also said that poor bushings esp on the trackbar will cause it to give unusual wear patterns. So my next step before I bring it in is to go through all the bushing and check them carefully. I might just replace the trackbar (the one that goes from the upper frame to the axle if I am naming it correctly) with the one on my parts car

A trackbar bushing or any other rear bushing will not give you tread wear on the inside of both rear tires. You either have excessive negative camber or excessive rear toe. There shouldn't be any additional programming required for them to rear what your rear axle alignment measurements are. Have them give you a printout of your rear axle alignment measurements and post them up here.

 

[ColoRAD]

FWIW as far as I know there's nothing to adjust on the solid rear axle.

 

[clearock]

There r no adjustments for the rear, it would be an alignment bar, heat, chains, and bottle jack...

 

[St Runner]

Its all a learning experience for me. I know about the front because i had to replace just about everything on my tacoma. I thought the rear was pretty simple but the more I know the more I don't know. The theory told to me was play will cause the wear pattern. Its easier to check and replace the control arms and trackbar bushings first, then get it aligned before replacing the housing

 

[JohnMc]

Park it on level ground and do a quick check with a carpenter's square. Set it on the ground and see if both rear wheels are vertical. There should be no angle to them at all.

There are no alignment adjustments possible on a rear axle unless you have some aftermarket adjustable length control arms. And even then, to the best of my knowledge, you'd just be adjusting the angle of the car as it goes down the road - the alignment of the rear wheels with each other is 100% controlled by the shape of the axle housing. So bent control arms might make the car drive crookedly (and require some steering to counteract), but there's no way it can make the two rear tires fight against each other.

Using a square against level ground only checks for camber from a bent axle housing, to test for toe bends you'd have to get a bit more creative - can be done with a measuring tape if the truck is lifted enough. Spin the wheels and use a pen to mark a line on them, then measure the distance between the lines in front and behind the axle. The pen mark removes any possible bent wheels from the equation. If you're not lifted enough to do the full 180 degrees, just do as much as possible.

 

[St Runner]

So just an update to this thread. First thing I did was replace the panhard bar with another one I had, that made an immediate improvement. I ordered whiteline bushings for the lower control arms and brought it down to the only place on the island that can do an alignment. They checked all the control arm bushings with a prybar and told me they could not check the rear alighnment until the bushings were fixed (no charge for that, they are good guys). So replaced the lower control arm bushings with the whiteline ( had to clean up the arms and make them look pretty) and replaced the upper control arms with a set I recently pulled off another 4runner in perfect condition. That made a huge difference, now the back end is tight and does not sway in the corners when you hit a bump. Brought it back to the shop this morning and threw it on the machine. Castor was just in spec and evenly distributed between the left and right. So it looks like the axle is not bent, it was just loose and moving around too much. Every road here is just a series of corners with a lot of elevation thrown on poor surfaces so tire wear is excessive to start with. I have never gotten more than 15k miles out of a set of tires. I am just going to let these wear out and see if they continue to show the same kind of wear.