Shredded ACR tire, look at my Alignment?

[Darius]

I recently had my Alignment done and my 1st day out with the new specs my left front tire corded bad after 2 sessions. I gave the alignment shop the info from this ACR spec sheet. It say's total toe at .14 degrees. I think maybe they didn't convert the degrees to inches properly. I would think the excessive tire wear came from too much toe out. Either way my front tires are completely ruined and I didn't even do the full sessions. I know a aggressive race alignment is hard on tires but I would think they would last much longer than this. The rest of the tire isn't even to the wear markers. Rears are fine.

[kverges]

Could also be too much camber. Toe numbers don't look excessive, just .03 in each side. I'd see if you can get tire temps net time out.

[ViperGeorge]

I don't think it was toe. The toe numbers don't look bad (a lot of folks would run between zero and 1/8" toe-in and your only at 6/100ths) but camber at -3.0 is more than I run and I believe more than what my TA 2.0 calls for.

[ACR]

camber ate my M3 tires just like this, was at -2.5

[TrackAire]

Something else is going on....3.0 of negative camber is not that extreme that two session will destroy the tire.

What was the air pressure cold and hot?

Are you sure that this wear pattern hadn't started before you even got on the track?

Were you experiencing a lot of understeer? You're generally turning hard to the left at LS, so the left front tire should not have worn first IMO.
Good luck finding the solution.

[Nine Ball]

Another possible scenario is if you lowered the car. This changes the geometry of the suspension's working range, and limits full travel, which might also be a reason for excessive tire wear. But, I'd lean towards the -3 camber on both sides being worse than the toe.

[LA STIG]

What track was this at? Also, what were your air pressures?

[kverges]

Another reason I mentioned camber wear is that the inside of the unloaded tire takes a beating. Body roll accentuates the static camber and it can get sort of "dragged" due to Ackerman. And if the car pushes it's even worse. I did exactly that to the outside of my GT3 front tires by being too lazy to put a track alignment on it. That's why I suggest looking at tire temps. 3 deg camber is not that radical, though. So I remain uncertain.

[CJW Racing]

Darius the same thing happened to me today but it was my 2nd track day.

I am trying to figure out the Viper-friendly technique a little more because I'm coming from GT3's like Keith- I have found that running the car too low PSI is worse than running too hot. It's better to start on 30-32 and take them to 39 than to run 3-4 laps at 26-30 trying to get them to 34-35. FWIW I think that is what caused my excessive wear as it was colder than polar bear balls this AM at Willow Springs for my first session and I started the tires too low- the wear was way worse than at Fontana with higher ambient temps and higher PSI.

[Darius]

I'm gonna have my alignment re checked, maybe something came loose who knows. I was running 30 psi cold all the way around, and going to 38 39. The tires were fine my 1st track day and I did 5 sessions, even wear. This was with the car lowered already but not aligned. When I brought it in my -camber was higher than what I had it aligned to. I noticed after my 1st session that the inside was dropping off. I was concerned about it because it looked like there wouldn't be much left and sure enough the next session killed them.

[ACR Steve]

You cant lower a car without re-aligning if you are going to track it let them do a corner balance as well........... bring it to a good race shop that knows how to do set up.

[serpent]

Question is Darius, are you going to go to the same shop? I read in the other thread that the front splitter was missing screws and the lug nuts werent even torqued!

[fuggles]

The Dodge spec for front toe seems off to me. Maybe their spec is for street use only. IMO you should run with some negative toe up front.

[mjorgensen]

My guess... 3 degrees is too much... what does the outside of the tire look like? does it look like you needed all that camber or does it look really good? too good?

All that negative camber will drag the inside edge under trail braking and when you have 39psi hot the crown of the tire will accelerate the inner edge wear also. Plus under hard braking the inside is doing most of the work rather then having the whole tire flat on the ground. Lets see the pictures of the outside edge if you have a moment please.

[Darius]

Question is Darius, are you going to go to the same shop? I read in the other thread that the front splitter was missing screws and the lug nuts werent even torqued!

I called them today and the owner was really apologetic and said he would pay for the missing bolts and do the alignment himself the next time. I'll bring it to him later this week.

- - - Updated - - -

My guess... 3 degrees is too much... what does the outside of the tire look like? does it look like you needed all that camber or does it look really good? too good?

All that negative camber will drag the inside edge under trail braking and when you have 39psi hot the crown of the tire will accelerate the inner edge wear also. Plus under hard braking the inside is doing most of the work rather then having the whole tire flat on the ground. Lets see the pictures of the outside edge if you have a moment please.

I'll take some tomorrow the car is at a shop getting the rest of the car clear bra'd.

[VENOM V]

I'm gonna have my alignment re checked, maybe something came loose who knows. I was running 30 psi cold all the way around, and going to 38 39. The tires were fine my 1st track day and I did 5 sessions, even wear. This was with the car lowered already but not aligned. When I brought it in my -camber was higher than what I had it aligned to. I noticed after my 1st session that the inside was dropping off. I was concerned about it because it looked like there wouldn't be much left and sure enough the next session killed them.

Darius, the more I think about it, I think this is the culprit. You said that it was at -3.5 deg front camber when they went to re-align it. If you did 5 sessions at -3.5 degrees on your previous track day, plus with your high hot pressures, you may have started your second track day with that inner edge already mostly worn away. I once raced my Mustang with a bent frame and only -2.1 degrees front camber. I went to cord on the outside in only 3 sessions. I would normally get a dozen+ sessions out of those tires. Yours is too much camber so it corded the inside, but same principal.

[FLATOUT]

You cant lower a car without re-aligning if you are going to track it let them do a corner balance as well........... bring it to a good race shop that knows how to do set up.

Darius as several people in this thread have already mentioned take a look at it again, and also measure fram to ground clearance if you can get to it up front. You should have no less than 4 inchs frame to ground for everything to work properly. Also try to be as smooth as you can into and mid turn. Your car at speed in a lot of instances weighs as much as a Jeep Grand Cherokee absorbing those corner G forces, imagine what that will do to the tire. Also some tracks will be tougher on tires i.e. Willow Springs due simply to the racing surface. I would make sure the car is setup properly and then play with your driving style a little to get more life out of each set.

Andy

[Darius]

Darius, the more I think about it, I think this is the culprit. You said that it was at -3.5 deg front camber when they went to re-align it. If you did 5 sessions at -3.5 degrees on your previous track day, plus with your high hot pressures, you may have started your second track day with that inner edge already mostly worn away. I once raced my Mustang with a bent frame and only -2.1 degrees front camber. I went to cord on the outside in only 3 sessions. I would normally get a dozen+ sessions out of those tires. Yours is too much camber so it corded the inside, but same principal.

I'm not sure about that. That 1st day I was looking at the tires after each session, not too hard since you can look through the hood. I didn't notice anything strange. After the 1st session on the 27th I looked and saw the tire dropping off bigtime on the inside. It also sounded different going around the turns, like a scrubbing howling sound. I think something came loose on the alignment. Will post what I find out later this week.

[Darius]

Darius as several people in this thread have already mentioned take a look at it again, and also measure fram to ground clearance if you can get to it up front. You should have no less than 4 inchs frame to ground for everything to work properly. Also try to be as smooth as you can into and mid turn. Your car at speed in a lot of instances weighs as much as a Jeep Grand Cherokee absorbing those corner G forces, imagine what that will do to the tire. Also some tracks will be tougher on tires i.e. Willow Springs due simply to the racing surface. I would make sure the car is setup properly and then play with your driving style a little to get more life out of each set.

Andy

This was all done before I did this track day, it's 4 inches in the front and 5.5 on the back. Although my car looked to be about 1/4 lower in the front than Todd's. It will go back to the alignment shop this week and I'll get it figured out.

[Rapidrezults]

This was all done before I did this track day, it's 4 inches in the front and 5.5 on the back. Although my car looked to be about 1/4 lower in the front than Todd's. It will go back to the alignment shop this week and I'll get it figured out.

So yours was also lower than Todds? I thought mine was 4x4 next to yours and mine was aligned to around 4-1/4 to allow for some settling per Mark J. It looks so badass slammed like that though.

[RickyBobby]

I was the new guy who ran with you guys at this event too (same dark blue colored SRT Viper, no stripes Ricky Bobby #62 theme). I also went to the same shop as you did to align my car before this event and here are my settings below. If you compare the alignment specs on the left front between our cars (mine was set closer to TA specs in general) I have less camber, more caster, toe similar, less SAI (?), and less Included Angle (?). Overall front specs between the two differ mainly in Cross SAI, and Total Toe where it looks like we are both positive total toe but mine slightly less at .03in vs. .06 in yours. My tire wear was was even for a track day, my center blocks look like yours, my inner block has no excessive wear, and the outer blocks showing normal wear also what you would expect after a track day. Only mods on my car is the Viper Exchange Suspension, and TA sway bars (front and rear). I did play with the ride height where there is about a 1.5 to 2 finger gap between the fender wells front and rear. When you go back to the shop maybe this can serve as some comparison points for your next alignment.

Anybody know how to adjust bump steer on Gen V? I asked the shop and they said there are no provisions for bump steer adjustment stock. Is there some aftermarket bump steer kit we need to adjust this?

[IMG]

[Dfunk]

I found this info while researching how to do my own alignments.

The vehicle's toe is one of the most critical alignment settings relative to tire wear. A toe setting that is just a little off its appropriate setting can make a huge difference in their wear. Consider that if the toe setting is just 1/16-inch off of its appropriate setting, each tire on that axle will scrub almost seven feet sideways every mile! Extend it out and you'll discover that rather than running parallel to each other, the front tires will scrub over 1/4-mile sideways during every 100 miles of driving! Incorrect toe will rob you of tire life.

[Nambo]

You can adjust bump steer. I would call Mark at Woodhouse and he can point you in the right direction, no pun intended.

[CarbonDan]

Sorry to resurrect this thread, but I'm in the same situation myself, similar alignment specs (-3.0 front), murdering front v720s just like this.
I'm putting on 19" hoosier r7s on Tuesday and getting the ride height adjusted again, recorner balance and realigned. Can you chime in on what alignment specs I should start with, particularly front camber, to optimize front tire life? What was the final culprit and solution to the original problems.?

[Lawineer]

Something that can contribute is not going fast enough, maybe?

The idea with negative camber is to make up for the suspension flex, so that it ends up being flat in turns. So the theoretical optimal amount of negative camber is dependent on the amount of grip (tires, conditions, etc). More grip, more neg camber. But if you don't use it all, the wheel doesn't get flat and you're riding on just the insides through the turn too- rather than distributing load across a flat tire. Negative 3 is a lot of negative camber for a street tire, but on the Kumhos and with all that aero, it's got tons of grip for that camber

FYI: On properly setup and driven race cars, insides wear the fastest anyway. You're always either wearing evenly (in a turn) or wearing the inside fastest (when in a straight line, especially coming out of turns and hard braking). But 2 sessions is very fast.

Maybe it's a tire pressure issue. What are temps across the tire?

Also, camber dictates what part of the tire will wear fastest. Toe is how fast it will wear. The more toe, the more the tires are "scrubbing" rather than rolling.