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Old 08-21-2013, 12:25 PM   #1
jaboyd
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Default Handling/tire wear

I have a stage II 2011 STI, 11k mi with coil-overs, lowered approx 10mm, WL RCA and Cusco rear adjustable control arms. Running -1.7 camber front, -1.4 camber rear and zero toe. Currently have AD08 tires but getting excessive wear on the inner front tires.

Trying to address the wear problem and a quirky handling characteristic.

First off, I don't track the car but generally do aggressive street driving (mtns and backroads). I usually rotate my tires every oil change (3k) and align it once a year. Bought the car with 4k mi on it and it had been autox a few times with these tires by previous owner. Owner aggressively set camber in front (approx -3) for the few events (2 or 3 I believe). I didn't notice any extreme wear when I purchased the car...but I didn't actually measure then.

Drove the car for approx 6 months (mostly backroads) and didn't see any abnormal wear. Drove on an 8 hr hwy trip and a few months later, looked at the tires and could see excessive front inner wear...rears are fine. The wear is on the inner most 1". Had the car realigned (before measurements - toe was still at zero and camber was around -1.8 frt, -1.5 rear). Reduced the front to -1.7 and rear to -1.2, and for good measure corner balanced the car.

Question: Could an extended hwy trip (500 miles) wear the tires that much with those settings??? Any thoughts or suggestions?

I have been running the car with the VDC off, S#, and DCCD in auto. Occasionally as I stand on the power in a corner I will get "torque steer" which I never had on my previous car (05 STI). This car is very stable with minimal push and virtually no over-steer, but the torque steer can be annoying.

Is there a better setup for the VDC and DCCD to eliminate the torque steer such as using DCCD auto -, or running the "green VDC setting? Since I've started experiencing the torque steer, could that be causing the inner front tire wear bc they are spinning?? Don't know whether these might be related.

Thx
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Old 08-21-2013, 08:45 PM   #2
Uncle Scotty
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what size wheels.....size and offset....and what size tires???

camber usually does not eat tires....but toe DOES.....id almost wanna say that the toe isnt really zero or the car is too low or the tires are too wide for the wheels...or some combination of those

are you sure that the car is only lowered 10mm?? and not 10cm

can you post your alignment sheet?
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Old 08-21-2013, 09:06 PM   #3
jaboyd
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Quote:
Originally Posted by Uncle Scotty View Post
what size wheels.....size and offset....and what size tires???

camber usually does not eat tires....but toe DOES.....id almost wanna say that the toe isnt really zero or the car is too low or the tires are too wide for the wheels...or some combination of those

are you sure that the car is only lowered 10mm?? and not 10cm

can you post your alignment sheet?
Appreciate your help! Yes the drop is 10cm NOT 10mm, approx 1/2" drop. Stock 18" wheels, AD08 245 40 18 tires. I've read all the cautions on ride height and after corner balancing they are LF 25 13/16, RF 26 1/4, LR 25 7/8, RR 25 13/16.

Can't upload alignment sheet but it was:
Camber LF. -1.8, RF - 1.9, LR -1.6, RR -1.5.
Caster LF. 6.0, RF. 6.2
Toe LF 0.0, RF -0.1, LR +0.01, RR 0.0
Total toe +0.01
Thrust angle 0.00
SAI. LF. 16.4, RF 16.6

One additioal point, when I corner balanced the car last week, the left front and right rear were lowered...the left front lowered 5/16" and right rear lowered 3/16". I was wondering if that could have overloaded the left tire (to much heat) on the inner edge?

Any thoughts on the VDC or DcDc settings contributing to the excessive front tire wear?
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Old 08-22-2013, 09:26 AM   #4
Samurai Jack
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Why did you choose those camber settings? Just curious.
They don't seem too high
Large camber settings can cause premature tire wear.

Did you align the car and then corner balance or did you corner balance and then align the car?

How was the car aligned?
Was it done by hand on an alignment rig?
Was it done by a computer on an alignment rig?

What I mean when I say "done by a computer" is there are systems where the tech sets the specs into the computer and the rig lights up to show the tech if the suspension is being set within the specs put into the system or not.

If the tech enters the specs wrong, your alignment will be off.
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Old 08-22-2013, 09:54 AM   #5
jaboyd
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Quote:
Originally Posted by Samurai Jack View Post
Why did you choose those camber settings? Just curious.
They don't seem too high
Large camber settings can cause premature tire wear.

Did you align the car and then corner balance or did you corner balance and then align the car?

How was the car aligned?
Was it done by hand on an alignment rig?
Was it done by a computer on an alignment rig?

What I mean when I say "done by a computer" is there are systems where the tech sets the specs into the computer and the rig lights up to show the tech if the suspension is being set within the specs put into the system or not.

If the tech enters the specs wrong, your alignment will be off.
These camber specs are fairly common and used by many local Subie owners. In general front camber settings of -1.7 to -2.0 and rears btwn -1.2 and -1.5 are widely touted as the acceptable range for a DD. I ran very close to those settings on my 05 STI and had great tire wear and good handling.

The alignment was done the latest Hunter machine (don't recall model #) and rechecked a few weeks later with string and camber guage...everything was fine. The experienced tech (race shop) used my specs.

I just did the corner balance last week and will have it realigned, but original alignment did NOT have a corner balance.

In my experience excessive camber wear tends to show up as a relatively wide but shallow sloped wear from inside edge towards center of tire. In my case it is a steep angle only about 1" wide. My rear tires have a classic camber slight "slope" across a 2-3" circumferencial area gradually disappearing towards the tire center. The fronts , however, are drastically angled.
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Old 08-22-2013, 10:23 AM   #6
Samurai Jack
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You should find out if the tech set your setting by hand, or used a computer-based system as I described earlier.

Race Shop or not, any tech can set the wrong settings.

Clearly, corner balancing after alignment will have negative effects as you have now changed your alignment, which could be the cause of the issue.

I have had tire wear previously on a non-Subaru, which looked just like bad toe alignment, but was in actuality overly negative camber.

Other than that, sounds a lot like your toe settings are off.
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Old 08-22-2013, 10:32 AM   #7
jaboyd
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Quote:
Originally Posted by Samurai Jack View Post
You should find out if the tech set your setting by hand, or used a computer-based system as I described earlier.

Race Shop or not, any tech can set the wrong settings.

Clearly, corner balancing after alignment will have negative effects as you have now changed your alignment, which could be the cause of the issue.

I have had tire wear previously on a non-Subaru, which looked just like bad toe alignment, but was in actuality overly negative camber.

Other than that, sounds a lot like your toe settings are off.

The tech used a computer (Hunter) and then I had it manually rechecked a little while later.....no change.

The alignment that was on the car when I saw the problem had been done before the corner balance, so yes I now need to realign.

Here's an off the wall question. Since I've been driving the car with vdc off (no traction control) and the dccd in auto position and noticing some torque steering after the apex of a turn under full throttle, could I actually be spinning the inside tire causing this wear?
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Old 08-22-2013, 01:39 PM   #8
Back Road Runner
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You might consider dropping tire pressure some to allow the carcass to flex and conform more readily.
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Old 08-23-2013, 09:38 AM   #9
Samurai Jack
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Quote:
Originally Posted by jaboyd View Post
Here's an off the wall question. Since I've been driving the car with vdc off (no traction control) and the dccd in auto position and noticing some torque steering after the apex of a turn under full throttle, could I actually be spinning the inside tire causing this wear?
Although you don't specifically state it, I presume you are getting relatively the same amount of abnormal wear on both the right and left front tires?

The wear could actually be "normal", based on your driving style, lots of backroads and mountian roads with lots of turning at speed. It may have been there, but you just happened to notice it after a prolonged highway run.

Large amounts of negative camber (I understand "camber specs are fairly common and used by many local Subie owners" are great for corners but not for prolonged highway driving. Could be part of your issue.
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Old 08-23-2013, 10:22 AM   #10
jaboyd
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Default

Yes, both fronts show similar wear, although the left is worse. The car usually driven only short distances on interstates or long distance higher speed straight roads. I've never seen this extreme type of wear on my 05 sti, but I was running RE070 or RE11 not ADO8s.

I'm speculating that there are several factors that have contributed to this excessive wear. 1) the AD08 may be more suseptable to front camber wear bc of the very flat tire face vs the rounder shoulders on an RE11 (for example). 2) the car had not been corner balanced when this happened (coilovers) and the left frt/right rear wcorners ere too high especially the front....likely leading to excessive temp build up on the inside front portion of the front tire. 3) I've only had the car 10 mos and was driving it with VDC off and DccD set at auto. I think that with that combination when I corner that I may be pushing too much power to the front wheels at the apex causing wheel spin and further heating the tire. I've started running the VDC at Traction mode (green light) and the DccD set at auto -. The car feels good with those setting so I'll check on the tire wear.
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