Uneven & Excessive Rear Tire Wear

[menchgelof]

My Vehicle: 2012 Legacy 2.5i with 205/60-16 tires.

 

I keep experiencing uneven tire wear on the rear tire on the inside side of the treads.

 

In this inner part of the tire, the first set of tires wore down to the cords after only 44k miles. The second set was getting close to bald after only 35k miles. The third set is already showing excessive wearing at 14k miles.

 

I keep getting alignments, and each time, the car is brought back into spec successfully, and it doesn't appear to be wildly out of spec in the *before* measurements (at least for the rear wheels). I even had the service tech verify the dimensions of the camber arm to make sure it wasn't bent.

 

It's never been in an accident, and I don't drive it aggressively. It's a daily driver.

 

Has anyone had experience with this kind of wear? Does anyone have any suggestions on what to investigate?

[Zee199969]

Your toe seems to be way off which could explain excessive wear

[whitetiger]

your rear toe is fuct. you should have a thust angle of 0. you car is probably dog tailing down the street.

 

until they get your rear toe fixed, specifically the right rear wheel and make it even with the left, you will always have an issue. your alignment shop is garbage for letting you leave like that.

[aperson]

If they keep adjusting the rear toe back into spec and it keeps going out either the shop isn't doing something right (torque, needs loctite?) or the balljoints in your toe link are shot and you need a new toe link. I'd have them take a straight edge and verify that the toe link isn't straight. That wear is because instead of the tire rolling straight it's always trying to turn right and the inside edge of the tire is the leading edge.

[menchgelof]

To clarify, the alignment measurements in the OP are the before readings. I think it's odd that the correct range is different between the two unique alignments (e.g., ±0.13° vs ±0.08° for rear toe). Perhaps non-updated Hunter data?

 

Attached to this post are the corresponding after measurements. I'm looking for help trying to figure out why they are able to correct the toe with each alignment yet it continues to get out of spec by so much. Any thoughts on this specific point?

[menchgelof]

If they keep adjusting the rear toe back into spec and it keeps going out either the shop isn't doing something right (torque, needs loctite?) or the balljoints in your toe link are shot and you need a new toe link. I'd have them take a straight edge and verify that the toe link isn't straight.

 

Ok, this is exactly the kind of advice I'm looking for: new ideas for what to check next. Thanks, aperson.

[whitetiger]

well, thats better.

 

range of acceptability is arbitrary. its just the limits where the block turn from red to green. any good alignment done should have precisely equal numbers from left to right and as close to the desired target as possible. the key numbers are thrust angle and steer ahead being 0.000000 and all else being balanced.

 

 

as said above, if your right rear toe adjustment keeps going out, you need to look for a worn or loose part back there. otherwise it will just keep getting loose and you will get more excessive wear.

[08SpecB_DE]

They should bring the camber on the RR out a little bit if there's adjustment left. .6 doesn't seem like much but it can make a big impact. It's possible your wheel bearing is bad in the RR and is causing the values to jump around.

 

I cringe every time I hear "in the green" when related to alignments because that does not mean it's good to go. I can also change the values to put any number in the green. WhiteTiger hit the nail on the head as far as describing a proper alignment.

[FLlegacy]

They should bring the camber on the RR out a little bit if there's adjustment left. .6 doesn't seem like much but it can make a big impact. It's possible your wheel bearing is bad in the RR and is causing the values to jump around.

 

I cringe every time I hear "in the green" when related to alignments because that does not mean it's good to go. I can also change the values to put any number in the green. WhiteTiger hit the nail on the head as far as describing a proper alignment.

 

Definite possibility there which brings up a good point, how are you not hearing or feeling the noise from the tires scrubbing away that is a lot of wear on one tire.

[menchgelof]

Definite possibility there which brings up a good point, how are you not hearing or feeling the noise from the tires scrubbing away that is a lot of wear on one tire.

 

The funny thing is I'm not noticing any sort of erratic movements, vibrations, or noises. I'm usually very sensitive to those types of things.

 

They should bring the camber on the RR out a little bit if there's adjustment left. .6 doesn't seem like much but it can make a big impact. It's possible your wheel bearing is bad in the RR and is causing the values to jump around.

 

My understanding is camber isn't adjustable on the rear wheels without aftermarket parts.

 

I'm lucky to have confirmed on here that this seems very much like an issue specific to my car. No one has mentioned anything similar happening to other 5th gen. Legacy's.

 

Does anyone here regularly perform alignments on their own cars at home? I would be interested in learning how, even if it's not solving this current problem. I've seen various tools and different techniques on YouTube. Would you recommend looking into it?

[08SpecB_DE]

Absolutely not! The amount of technology in alignment machines is far superior to anything you could do at home. The smallest amount of movement can make a huge difference in your specs.

 

I just saw the change in tolerances on your paperwork :spin: ABORT MISSION! Take it back and demand you watch them do the work. They never did your alignment, they changed the specs to make it seem like they did something. Those scamming sons of bitches! Call them on their bullshit and demand it get fixed!

 

I'm so sorry I missed those posts earlier. I've easily done over a thousand alignments (only one at previous shop who did them for a little over 8 years) all on 2 different style Hunter machines so I know them like the back of my hand. Hell, I'll call them for you and pretend to be someone who knows you except the caller ID would show a Delaware number. You my friend, have been getting dicked over by that shop and that's why you are prematurely wearing your tires along with probably needing a camber kit for the rear. More importantly, demand it gets put on the rack while you watch and make sure all the pins on the turn plates are out so they can pivot. Also, make sure they start fresh and do not bring your car back up on the machine which could save the changed data.

[08SpecB_DE]

If there's no camber adjustment in the rear they should bring that to your attention and sell you the kits to fix the issue or let you know they couldnt fix it, not change specs to make everything seem kosher. That's very shady and bad for business.

[dgoodhue]

Does anyone here regularly perform alignments on their own cars at home? I would be interested in learning how, even if it's not solving this current problem. I've seen various tools and different techniques on YouTube. Would you recommend looking into it?

 

I have my own alignment tools. The quick summary I would not do it for your vehicle. Your vehicle is already potentially crab walking down the street as it is. Alignment are more complex when dealing with F to R alignment issue.

 

My tools cost a little over $200. My fun vehicle has an aftermarket coil over suspension. I bought the tools to do the job it has a custom tool (tight clearance) to access the camber/caster bolts plus I thought would want to the able to make adjustments if I raise or lower the ride height (which I haven't touched) The vehicle only has front end adjustments, the rear has no adjustments which eliminate one variable. My tool are pretty accurate. The toe can be done 1/16" and camber/caster is analog and has 1/16 deg marks. I set up my garage to shimmed the vehicle and make sure the contact points are level to ensure I could an accurate alignment. Their is a some of learning curve. I did 3 alignments on that vehicle, initial, after it settled, and once to change the settings. When I replaced the tires last years, the shop does courtesy alignment check. I explain to the tech I did my own alignment and asked to see the numbers. They all were within 0.01 to 0.02 of what I had set them too.

 

Since then (circa 2005) I 'aligned' one of my daily driver with the tools (it only had front toe adjustments) and use them to spot check my vehicle every couple years.

 

When I get around to doing the springs, struts and rear LCA on my Legacy's suspension, I am going to have it aligned by a shop. It has front & rear camber and toe adjustments, which the rear adjustments in relation to the front come more complexity. I am not going to put the effort to figure it (which will probably cost me more time than it worth to get it the accuracy that I want.) I will roughly set up my car with my alignment tools prior to going to the shop. It will allow me some time for the springs to settle as well.

[menchgelof]

Wow, so much to respond to. Thank you all for your input on this issue. It's helping me see the alignment data and changes over time in a new perspective.

 

I put the before and after measurements next to each other in some new images attached to this post: I think it will be a lot easier to make comparisons this way instead of having them as separate posts above. Additionally, I found another alignment sheet. I was trying to have them diagnose the tire wear. Alignments 2 and 3 are two weeks apart, and there's already a significant shift in toe on the RR wheel (0.18°).

 

Also, these alignments were performed at different shops: Alignment 1 was at one shop, while Alignments 2 and 3 were at a different one. I definitely see the differences in tolerances between the two shops, but I don't see Shop B changing numbers between alignments.

 

I get what whitetiger said about tolerances being arbitrary, so I'm less concerned about tolerances being different between shops or even being changed at one shop just to get measurements to turn green. I'm more concerned about the actual readings. Toe, thrust angle, and steer ahead all appear to be very close to zero after aligning, which seems great. Are some of you saying they can fake those actual measurements, or am I misunderstanding you?

 

For the advice on DIY alignments, I figured as much. I didn't think any home kit would be able to consistently achieve accuracies to 0.01°, at least not without some excellent alignment experience, which I certainly do not have.

[whitetiger]

can numbers be faked, yes. id be more concerned about what was out each time you went to a shop, and that is the right rear wheel. it seems like there is an issue keeping things tight.

[menchgelof]

While we're discussing parts that could be damaged on my vehicle (ball joints, toe links, etc.), I thought of something else that might be related.

 

When I am pulling out of a driveway and accelerate slightly aggressively, I get a rumbling vibration from what sounds like the rear of the car. It has always done this, so I wondered if it was some quirk of the AWD system (this is my first AWD car). It lasts only about a second, ending as soon as the car begins to straighten out. It happens with any other similar, tight radius, 90° turn and aggressive acceleration. It doesn't sound or feel like tire slippage.

 

Does that sound normal, like it's a function of a slipping differential (I'm making wild guesses here)?

[GTEASER]

If you are having issues with the rear toe not staying within spec, you need this stuff. brandon.mol had issues with the stock eccentric toe adjusters, they just wouldn't stay put, and he did something similar to what I did on m Forester.

 

 

These will fit our Legacys. This install was on my 2009 Forester XT.

 

Installed the SPC adjustable toe arms and SPL toe lockout this afternoon to get rid of my toe out situation since the stock toe arms were maxed out following lowering the car and installing adjustable lower control arms. The adjustable LCAs corrected my camber from approximately -2.5 to -1 degree by making them about 3/16" shorter than the stock LCAs. It took 2 hours.

 

Beefy units....

 

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I rigged up a way to check the alignment with 2 pieces of aluminum angle stock and bungee cords (we used to do this on the racecars when I worked on an SCCA Club team) so I could measure the toe in the front of the tire and at the back to compare the measurements. I also didn't want to affect the thrust angle and I needed to bring both sides in equally so I also took a measurement near the toe arms from the inside wheel lip to a point on each side near the pickup for the toe arms on the subframe. These measurements are not necessarily equal, mine were 1/16" different between sides. I wrote down all of these. My alignment rig may look crooked but the rear was on ramps so it was nearly level in relation to the surfaces that the tires were sitting on.

 

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The lockout kit fit perfectly, it is a quality kit. The inboard lockout bolt gets torqued to 88 ft/lbs (after the car is back on the ground) and the castle nut on the tie rod end gets torqued to 44 ft/lbs. I reused the stock cotter pin. The SPC toe arms are very nice, but the inboard bushing is rubber like stock, not a hard bushing, so I wouldn't use these on my Legacy GT where hard bushings are imperative for all out handling for track days. My Fozz is more of a Sport oriented family wagon.

 

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Following the LCA install and alignment, my total toe out was 3/8" or about 1.2 degrees (3/16" and 0.6 degrees per side respectively). I brought each side in 1/8" (at the rim to subframe measurement) and it turned out perfectly, 1/16" total toe in which is less than 0.1 degrees total toe in.

 

Additionally, the rear tires had gotten very loud from the toe out, they were essentially scrubbing the ground as they turned. The tires are virtually silent now when rolling down the road at highway speeds.

[08SpecB_DE]

While we're discussing parts that could be damaged on my vehicle (ball joints, toe links, etc.), I thought of something else that might be related.

 

When I am pulling out of a driveway and accelerate slightly aggressively, I get a rumbling vibration from what sounds like the rear of the car. It has always done this, so I wondered if it was some quirk of the AWD system (this is my first AWD car). It lasts only about a second, ending as soon as the car begins to straighten out. It happens with any other similar, tight radius, 90° turn and aggressive acceleration. It doesn't sound or feel like tire slippage.

 

Does that sound normal, like it's a function of a slipping differential (I'm making wild guesses here)?

 

Sounds like the rear diff. When is the last time you changed the fluid?

[menchgelof]

Sounds like the rear diff. When is the last time you changed the fluid?

 

The rear differential fluid hasn't ever been changed. I've seen lots of mixed advice on the subject. In the official maintenance schedule, it's listed as *Inspect* every 30k miles, not *Replace*. Some people think it's good for a long time, maybe 100k miles, especially under non-severe driving conditions.

 

Do you disagree?

[FLlegacy]

I disagree completely. So then how many times have you inspected it?

[aperson]

The rear differential fluid hasn't ever been changed. I've seen lots of mixed advice on the subject. In the official maintenance schedule, it's listed as *Inspect* every 30k miles, not *Replace*. Some people think it's good for a long time, maybe 100k miles, especially under non-severe driving conditions.

 

Do you disagree?

 

As a general rule of thumb in my Subies I've replaced the diff fluid when I do the tranny fluid. It's likely overkill but it keeps me on a schedule and I get to make sure there are no metal bits in the oil too.

[08SpecB_DE]

I disagree completely. So then how many times have you inspected it?

 

+1. Change the fluid out immediately and pray you don't have a lot of metal draining out as well. In the most broad term, gear oil is like engine oil and should be changed out every now and then. Always follow severe conditions even if you don't beat on the car.

[dgoodhue]

If its the first differential oil change, there will be likely be a little metal glitter in the fluid from the break in period. My had some glitter when I changed it 20k miles. I have been changing with the trans fluid every 30k. I am not sure if its needed every 30k but its slightly less than a quart of gear oil and I have the tools to make the job easy.

[menchgelof]

I've never had the differential oil checked, actually. I didn't know anything about differential maintenance before it came up in this conversation; I've never had to maintain a car that wasn't FWD with the differential in the transmission. I assumed it rarely necessary since there is no scheduled replacement in the official maintenance schedule.

 

If there's damage already done, there's nothing I can do about it now. All I can do is change the oil as soon as possible. I'm glad 08_SpecB_DE and FLlegacy said something. I'm grateful for all the advice here: you've all been really helpful.

[08SpecB_DE]

In your defense, you are correct about normal servicing not recommending it to be changed out even up to 120k miles. Before you drain the fluid, make sure the fill plug breaks loose first.