(autocross) Suspension gurus help!! My tires are wearing outer edges. Got pics!!

[redsx13]

The car car is an 03 350z, it is a daily, but also used in autocross. I'm am not particularly new to the autocross scene, but i do lack in my suspension tuning skills. So please, enlighten me!

so, Ive always had a problem with my front tires wearing the sidewalls; and my question is, what is the best way to fix this? more negative camber would seem the most obvious choice, but i was also wondering of more positive caster would have a beneficial effect on sidewall wear, it was also mentioned that stiffer anti-sway bars would prevent this. Advice? (anyone running a z in autocross want to share their alignment specs, please?)

here is my current setup,Tein lowering springs, lowered about 1.5-2.0 inchesTokico shocks/struts255 40 18's up front265 40 18's in the rear

Everything else suspension-wise is stock. (please don't tell me my car needs an alignment, this problem is a result of racing not daily street use!)

^^ the sides of this tire are completely bald.^^ another look at this horrible tire wear.^^Inside of the tire; not much negative camber wear at all. (this is what the tread should look like on the outside)
Modified by redsx13 at 2:35 PM 3/23/2009

[Darius]

I'm going strictly off of dusty old memory here, but wasn't there a recall for this because this was happening to a lot of tires (fronts) on the early 350Z's? Search for feathering and 350Z and see what you find.

[musashin]

I know too much toe-in can cause that. Could that be it?

[redsx13]

wasn't there a recall for this because this was happening to a lot of tires (fronts) on the early 350Z's? Search for feathering and 350Z and see what you find.

I know too much toe-in can cause that. Could that be it?

no!! lol. My alignment is not off!

The feathering you see is from hard breaking and the outer tire wear is from the tire rolling over while cornering at high speeds, which is usually a result of a lack of negative camber. A good example would be why all you guys with lowered cars (And no adjustable camber arms) have inner tire wear on the rear. its the same thing.

Where are all the people who track their cars!! If you race your car you have had this problem!!

[Gabes13]

tire pressure?sorry buddy but close to stock alignment isn't good enough for road race. More negative camber will give you a greater contact patch on the outside wheels when taking turn. caster will help turn-ins but shouldn't be the determent of your tire wear. same with sways

[redsx13]

tire pressure?sorry buddy but close to stock alignment isn't good enough for road race. More negative camber will give you a greater contact patch on the outside wheels when taking turn. caster will help turn-ins but shouldn't be the determent of your tire wear. same with sways

I know stock alignment isn't good enough for road racing, that's why i made this post!

i messed around with the psi ALOT. finally ended up with 48psi up front and 42 in the rear. sounds strange, but it worked out pretty well. the higher psi in the front was mainly to compensate for my lack of negative camber. like i said, my alignment is mostly stock, the 1.5-2.0 inch drop has added a good amount of negative camber, but obviously not enough in the front.

[musashin]

Ok, now I'm confused on exactly what you're asking here. You say you know you need more negative camber to fix this, but you want another way to fix it? Is that what you mean?

[redsx13]

Ok, now I'm confused on exactly what you're asking here. You say you know you need more negative camber to fix this, but you want another way to fix it? Is that what you mean?

Yep, reason being, i already have a s*** load of negative camber both front and rear, but for some reason i still wear the outer edges of the front tires.

I actually think i found my answer, believe it or not Sway Bars actually effect camber. With stock sway bars, the car is more prone to body roll, the more roll, the more positive camber.

For example, this Evo has a ton of negative camber, but look at the amount of camber it has on this turn. By comparing the red and yellow lines your can find the amount of camber relative to the car, this is controlled by static alignment, such as adjusting camber arms, front pillow ball mounts, etc. By comparing the red and blue lines you can find the amount of camber relative to the road, this is controlled by anti-sway bars, and suspension stiffness. As you can see, this evo actually has too much positive camber on this turn, despite its massive amount of negative camber on the alignment rack.the blue line represents cool hugh?

Modified by redsx13 at 10:47 AM 3/27/2009
Modified by redsx13 at 10:50 AM 3/27/2009

[scole]

Yep, reason being, i already have a s*** load of negative camber both front and rear, but for some reason i still wear the outer edges of the front tires.

I actually think i found my answer, believe it or not Sway Bars actually effect camber. With stock sway bars, the car is more prone to body roll, the more roll, the more positive camber.

For example, this Evo has a ton of negative camber, but look at the amount of camber it has on this turn. By comparing the red and yellow lines your can find the amount of camber relative to the car, this is controlled by static alignment, such as adjusting camber arms, front pillow ball mounts, etc. By comparing the red and blue lines you can find the amount of camber relative to the road, this is controlled by anti-sway bars, and suspension stiffness. As you can see, this evo actually has too much positive camber on this turn, despite its massive amount of negative camber on the alignment rack.the blue line represents cool hugh?

Modified by redsx13 at 10:47 AM 3/27/2009

Modified by redsx13 at 10:50 AM 3/27/2009

wtf?

[ashibah83]

i dont really think that the picture is a very good representation of what you trying to explain, because of the rear slip angle being greater than the front slip angle and the counter steer, also the suspension on the 350's are a multilink type( if i recall correctly) so the camber gain during cornering shoud be near enough to offset the "roll". how much front camber are you running?? i run -2 egrees on my dd (which i drift quite frequently) and dont see any feathering on the front of my car(s13), the amount of weight transfer you have may also play a part, front anti-roll bars may help but may also cause more understeer, personally i would rather deal with a little bit more rapid tire wear than understeer, and if you run -2 degrees or around there you should still get decent mileage out of your tires as long as your toe is still in specs, i have run the same 2 tires on my car for over a year, Falken Azenis RT-615, with numerous track days, and drift events
Modified by ashibah83 at 6:28 PM 3/31/2009

[ashibah83]

thinking about it your stock struts may be giving your susension too much travel allowing for too much camber gain on turn in, simply switching your OEM units for something aftermarket, with shorter travel and better valving for aggressive driving may be in order

NM after reading your OP disregard what i just said about your struts....unless they're simply OEM replacement

[redsx13]

i dont really think that the picture is a very good representation of what you trying to explain, because of the rear slip angle being greater than the front slip angle and the counter steer, also the suspension on the 350's are a multilink type( if i recall correctly) so the camber gain during cornering shoud be near enough to offset the "roll". how much front camber are you running?? i run -2 egrees on my dd (which i drift quite frequently) and dont see any feathering on the front of my car(s13), the amount of weight transfer you have may also play a part, front anti-roll bars may help but may also cause more understeer, personally i would rather deal with a little bit more rapid tire wear than understeer, and if you run -2 degrees or around there you should still get decent mileage out of your tires as long as your toe is still in specs, i have run the same 2 tires on my car for over a year, Falken Azenis RT-615, with numerous track days, and drift events

Modified by ashibah83 at 6:28 PM 3/31/2009

Actually, my car doesn't have under-steer..at all, it is very balanced, the feathering is a result of hard breaking, it is not related to the wearing on the sidewall which is caused by lack of negative camber/side wall roll.

Drifting doesn't cause wear like this because you are not sliding the front tires or breaking as hard as you would in autocross, I have a s13 as well, (strictly a track drift car), and i know what you mean about the front tires, i have been running the same front federal 595's for a while, and the tire wear looks pretty normal, nothing crazy like the tires on the Z. Autocross is a whole different sport.

The thing is, i am not going to fix the feathering, i cant, unless i drive slower. lol. Frankly i don't give a s*** about my tire wear as long as im getting as much grip as possible. It Might be time for some nice anti-roll bars (adjustable, front and rear), i think i just push this car too hard, and the factory parts just weren't designed for it.

p.s. i know the picture isn't that great, its just an example, plus its drifting, so your right, you have to factor in the slip angle and s***, and its on a banked turn which doesn't really help with what im trying to prove.
Modified by redsx13 at 8:10 PM 4/2/2009

[redsx13]

Im going to hit up my local alignment shop tomorrow and i'll let you guys know what my specs are.

[bboixtc]

Yeah do that, When I first got my 4ws lude, I was wondering why the outer part of the rear wheels were starting to wear more than non 4ws ludes. I got the alignment done on the rear wheels and everything was fine.

[redsx13]

Here are my specs:

Front:Slight toe out-1.5* camber

Rear:0 toe-2.0 camber

I'm thinking if i wanted to compensate for the front wear i either need to get 255/265 35's instead of 40's, or i can run -2.0* camber up front.

Where are all the suspension people?? this is the Tires/Wheels/Brakes/suspension section. or are people too busy trying to fit +Omm rims on their car, and the only thing that they know about Camber is that if you run more negative you can fit higher offset wheels.

[skyvia01]

How about caster? Too much caster could cause that wear under hard braking. And how much is your front toe out?

[redsx13]

How about caster? Too much caster could cause that wear under hard braking. And how much is your front toe out?

i have no clue on the caster, as for the front toe out, its almost at 0, so i dont really think thats it.

[nifares240]

you need to zero out your front toe. you will just have to understand that you're racing your car. you'll wear out your tires faster than daily driving. it could be the type of tires you're running. high performance tires do wear out fast.

[RustspecS13]

That looks like positive camber wear to me. It either has too much body roll or not enough camber gain/static camber.

I was getting that one one of my front tires at a drift track on my s13. I added .6deg of camber on that corner and it stopped wearing. Id try an additional .5-6deg more on the front.

I run 205/50/16s on my 16x8 15offset spormax 501's. I have 3deg of front camber and 2.5deg of rear camber. My tires wear flat since I drive so hard so often.

Maybe you could try a stiffer sway bar to help eliminate some body roll. Or if your camber is already adjustable then if its free try that first.

If your alignement guy is worth a crap he should have measured caster along with everything else. Did you just not remember it or get a print out? If he didn't measure it Id be weary of going back there. I am a certified Hunter alignment tech BTW.

~Alex

EDIT- Toe out wear, is similar wear only on the inside of the tire. It doesn't look like he has enough toe out to get that wear yet.

Oh and another thing, you dont have any loose parts do you?

[hai1206vn]

Yep, looks like body roll made those tires work on the outer edge. Many lowering springs are too soft for the amount of drop they give. Stiffer springs and/or stiffer sway bars up front will cure the problem. Of course you have to tune the rear to match, or the car would understeer.

Stock camber curve works with stock height. If you lower the car to almost out of that good camber gain range, but the springs/sway bar aren't stiff enough to keep the suspension moving in that range, it probably handles worse than stock