I'm running an almost square 265/275 front back tire setup (Advcan AD08) at the track and the car feels pretty well balanced and I have no trouble beating on a number of faster car with meh drivers. What I'm concerned about is I still get much more wear on the outside front edge of the tire than the inside.

This happens although I'm up to 3.2deg negative camber front (2.5 rear if it matters). I have the car roll relatively in check with hotchkis anti roll bars (med front/med back) and hks hipermax coilovers.

I'm making an effort not to overdrive the tire, but alas still see more edge wear than I would like.

Should I go with more neg camber, 3.2 already seems like a lot. Also my moonface roll center adjustment kit just arrived and I'm wondering if I can expect to see better front tire wear when that goes in?

Any advice or suggestions?


here's the vid
<iframe width="560" height="315" src="http://www.youtube.com/embed/gx0NIaorQ0E" frameborder="0" allowfullscreen></iframe>


Thx!
Mario

 

Do you have any videos so we can see how the car is behaving and rolling?

 

What is your toe setting?

 

Unfortunately no video other than a helmet cam, I'm not sure how useful that will be as my head is bobbing around quite a bit. I can still post it though if you guys think its a good idea.

My full alignment settings are as follows:

front:
camber L/R : -3.2 / -3.2
caster L/R: 8.2 / 7.7
toe L/R: 0.04 / 0.04

rear:
camber L/R: -2.5 / -2.5
toe L/R: 0.14 / 0.14

Also minor correction on my initial statement, my hotchkis sway bars are MAX stiff front and MED stiff rear and as mentioned the car does feel neutral/very slight understeer-ish.

I also took another look at my rears and the rear tires also show more outside edge wear than the inside edge. Not as pronounce as the front tires, but def. same scenario.

Thanks!

 

I would like to see the video.

 

edit:uploaded video to 1st post

 

Any tire temps?

The G35 is a heavy car so you can expect a lot of outside shoulder wear. Even with the bars you're getting a lot of roll (+5 degrees) so your effective camber is close to zero on the outside tire. What you need is more spring.

 

First thought: What are you running for tire pressures? It's possible that since the tires you're running have a relatively soft sidewall, more pressure will effectively increase the tire sidewall stiffness and the tire will flex less.

Second thought: NJMP Lightning is very heavily biased towards right hand corners. Is the wear pattern the same on the left and right, or is the wear on the LF comparatively more to the outside than it is on the RF?

Third thought: It could very well be that the toe in is what's causing the wear. For track setups, they like 0 to a smidge of toe out in the front.

Fourth thought: +1 on the more spring idea.

 

John, I was hopping you would drop in. No tire temps, but I will be sure to monitor at the next track day. I'm at 9kg springs front, 9kg rear (oem rear location) on HKS coils right now and actually have been considering going up to an 11kg spring in the front so that I might be able to go back to a medium setting on the front sway bar (max right now). Good idea?

tire pressure: ~38 psi hot (I kept letting air out until I saw about 38 on all 4 corners at the end of the run)
cold: driver side is ~32 both front and rear, pass side is ~34 front and rear.

I'm assuming that the 2psi difference in cold tire pressure I see is as you mentioned NJMP Lightnings bias to right handers. However I didn't see much of a noticeable difference in wear between left and right, maybe slightly, but i can honestly say i saw outer tire wear on both sides.

Right now I'm leaning to the front spring and toe adjustment as my course of action per the recommendations, so probably:
11kg front springs
0.02 toe front
0.10 toe rear (too much? too little? ...car is still driven on the street and I was getting a bit squiggly under very hard braking)

Thank you for all of the great info !

 

IMO yes, it is a good idea for the track, but the big question is if you think that you can tolerate that stiff of a front spring on the street.

38 seems a little bit low for a street tire on track, but is high enough where it's not the root cause of the wear issue, and the fact that it's happening on both sides equally confirms that. The difference in the left and right cold pressures is absolutely due to the characteristic of that particular track.

I'd leave the rear toe alone for the moment. The stiffer front spring will reduce the nose dive under braking, and will also slightly reduce the rear lift under braking. Less toe in at the rear will make the car less stable under braking, not more stable.

 

thanks kfoote. I prob won't mess with the rear toe for now.

I'll definitely update this thread upon making some changes to the setup and the next track day. Obviously I need to start monitoring tire temps as well.

 

More front spring is good. Make sure your shock rebound valving can handle it. Ride harshness on the street has more to do with shock compression damping, bushings material, tire sidewall height and air pressure, and longitudinal front suspension compliance. Spring rate isn't as big a factor.

 

I know this is a long shot, but how are your front suspension components? Might be a good idea to check your steering knuckles and shocks.

 

Lots of good responses. I'd like to tag on a couple of related questions rather than start a new thread if the OP doesn't mind.

I've got a square set up with 265/40/18 street tires on 9.5", +15 RPF1s with no spacers. Stock suspension, stock alignment. I'm running 35 psi cold all around, usually around 40 psi hot. So far tire wear is pretty even with a just little extra wear on the outside edge.

Is this a reasonable basis for an HPDE-er to leave those pressures alone?

Second, I have never actually measured tire temps. I do not have a tire temp gauge (pyrometer). I do have an IR temp gauge. Is there any reason an IR thermometer wouldn't work for a reasonable approximation?

 

I would say it depends, if there is anything I learned from the responses here is that you absolutely NEED an accurate way to measure tire temps in order to make an accurate assessment. Do you have any adjustable control arms installed or is your car running completely stock alignment specs?

Also can anyone recommend a nice and relatively accurate pyrometer, i've never had luck with finding accurate IR thermometers, so not sure if I trust them for tire temps.

 

I can't speak for this pyrometer but Discovery Parts is great to do business with:

http://www.discoveryparts.com/cgi-bi...ngacre&pid=138

My little IR thermometer has been reasonably accurate in other applications but not sure about tires. There must be a reason they are not used.......and that would have to be accuracy...I guess.

My suspension is totally stock, alignment is oem spec.

 

I think I'll be picking up this one, its not cheap, but it'll store all 12 tire temps in one go vs running around with a clipboard, pen, and temp gauge:
Gauge

 

I have used both probe and IR types, and compared the two at the same time on several occasions. The short version is that an IR pyrometer will read a bit cooler, is more critical to taking the temps right when the car comes into the pits, and is worthless if you happen to have driven over a wet spot on the track in the track on your way into the pits, but under most normal circumstances, if you are looking for the spread in the tire temps and not the actual rubber temperature itself, an IR pyrometer is fine.

 

Thanks. Certainly can't hurt getting some numbers to see if they tell me anything since I already have the thing.

Might not know what to do about them since suspension is stock and I can't change alignment much anyway. But I can certainly play with air pressure and see what that does.

 

Just wanted to pop in this thread and give a brief update. I ended up doing two things for now attempting to improve the cars roll center. Alignment changes are coming up next.

I got a chance to do a track day at Pocono this past weekend, which was doing a 2 track event. It was both the South/East infield and Long course. I ended up doing only one session on the long course and 4 on the South/East infield and for those that don't know the South/East course is a tight and technical really really fun track with very smooth curbs that are a load of fun to hop.

I walked away with what was definitely a noticeable improvement in front tire wear. We were running in the clockwise direction and the left front was wearing evenly and smooth across the tire with no real signs of graining. The right front did have some wear, but it was even across and most likely due to my poor/overzealous driving at times.

I'm quite happy with the Moonface adjusters, definitely noticed a reduction in roll and better turn in. If anyone is considering them, go for it! I will do the recommended alignment changes next and see how it goes. Lime Rock Park in August should be a good test for the alignment