pouchonnet

Hi guys, I just purchased of set of the track edition v2 wheels and I love them. They look so beefy compared to the stock touring wheels and the traction in corners is amazing. I paid $400 for the set but the rear tires have 15% left in them. Anyway. I'm experiencing a weird feeling in the rear end. It's very inconsistent... You feel like you're going left to right, i espescially felt it once when i floored it, i thought i was going into the ditch because of the wobble. It's very inconsistent as i said, sometime i floor it on a nice road and it's fine, but on a bumpier road, the wobble is constent... I'm very confused. Also at low speed you don't feel it.

I know it could be a couple of thing but i can't pinpoint it. I tried putting air to 40 psi as it was recommended in another thread and it feel still wobbly. The wheels itself doesn't have flat spot. Should i just bring it to a mechanic to get it balanced then if it doesn't work what else should i try?

Thanks for the help

dkmura

iTrader: (64)

A "wobble" is hard to quantify, but I assume you mean the rear end gets loose under power? If so, it could be the rear tires are simply used up, and the rubber compound has become so hard it simply spins. The only solution--once you've ruled out any mechanical issues--is to replace the tires.

dkmura

iTrader: (64)

Ah, one more suggestion: it sounds like you simply bought these wheels/tires and bolted them straight to your Z. There's also the possibility they've been damaged and the runout is excessive on either the inner or outer sections of the wheel. This cannot be easily seen to the naked eye, but can be measured on a tire balancing machine, or at a wheel repair shop.

pouchonnet

Yeah i was too excited but it was dumb because the wheels do look beat up... Do you think that if they have excessive wear they can be fixed or i just wasted $400?

MicVelo

Forged wheels rarely bend to the point of creating that serious of an issue. If the wheel hit something, you'd pretty much see it beyond regular tire rash. I'm with dkmura that the tires are just spent. With only "15%" left, that's plenty of time on the road for things to occur that can destroy the tires' internal belts (impacts, excessive heat build-up and heat cycles, or just plain poorly built tires) which is the most likely culprit.

You didn't say what kind of tires. Pirelli, Bridgestone RE040s and RE050s, and even Michelin PS are actually rather prone to "invisible tire wear" as I call it. Tread depth is just one small aspect of a tire's wear. I have personally thrown out one or more of the aforementioned tires at 4/32nds simply because they degraded so badly in dry grip, ride, wet performance.

Keep in mind, in "true" tire tread life, that's 50% gone; because tread on a typical tire is 10/32nds and considered legally dead at 2/32nds - yielding 8/32 of "use" life. Always measure tread depth at the wear markers if you want to get a rough idea of "life left", NOT to the base of the tread. (You only want the full depth measurement for estimation.)

RedlineHR

iTrader: (1)

I feel you, OP! You lost me at "wobble" which to most, implies a high-er frequency oscillation, but you brought me back in at the left-to-right "steering feeling" from the rear.

I have this exact sensation now in my car and I have a theory. I thik Mic Velo touched on it already though. I'll elaborate

Let me also ask another variable... is your car lowered? How much negative camber do you have in the rear?

I ask for two reasons... I have Michelin Pilot Supersports with what looks like 4/32 of tread in the rear. many tires, as they wear towards the end of their life, reveals or exposes a harder compound of rubber. This harder compound reduces the rate of wear towards the end of the tire to minimize hydroplaning in the wet and you lose the effective dry grip. So for one it sucks that I am losing stickyness with what looks like decent tread remaining, but then consider that I've put 20k miles on these tires and am a very aggressive, er.. spirited driver. So I have definitely gotten my money out of them. BTW, the old Goodyear Eagle F1 GS-D3 was much worse.. wearing through to harder rubber within 10k miles. Never again!

Why does this matter and how does negative camber play into this? Well, consider that when you start getting significant negative camber in your suspension, the wheels have a tendency to push in the direction that they are tilted in. (Some negative camber comes stock and increases as you lower the car unless you run adj camber arms to dial it out)

So your two rear tires are pushing in towards each other at equal force so you don't feel much... UNTIL one side or the other loses traction.... Bam! the tire with grip pushes your car sideways until both tires grip again, And you feel like you have rear-wheel steering.

More rear camber exacerbates this effect. Have you heard of z-drivers who said they were just driving along the highway and their car started to fish-tail and spin for no reason? Usually it's raining in their scenarios.... one rear wheel hydroplanes (loses traction) and the tire with grip pushes inwards. Imagine that happening at 70 MPH in the rain! I used to feel this same thing in my old e36 M3. It had so much negative camber in the rear, I'd have to slow down to 45MPH in heavy down-pours because the rear end would jump left and right.

I have this feeling in my car now with only 300 HP at the wheels and running 305/30/19 Michelin PSS tires with 4/32 tread left and sitting at -2.5 degrees of rear camber. And it's bad in 1st gear and second gear. I just can't put down the power so I'm looking at new tires...

On that bumpy road @ WOT, you are getting lots of slight wheel spin which cause this feeling of instability... so air back down first, and get new tires second, then see if you still feel you have an issue.

pouchonnet

Hey! Thanks for the helpful information. It was indeed the tires since my car wasn't lowered and didn't have any camber. The tires had been sitting outside for a year in the cold weather so they we're warped i imagine. Unfortunately, i totaled my Z 3 weeks ago so i'll never experience what's it's like having brand new tires

dkmura

iTrader: (64)

What did you decide to do with your wrecked Z?

pouchonnet

Sold it to someone who parts out Z/G for a living. Got $3500 CAD for it and that included full exhaust and coils. A lot less then I wanted
Looking at 300zx atm.. Not sure what i'm getting next. I loved my 350z but it was missing something I feel like.

dkmura

iTrader: (64)

Looking at the wreck, it sure looks like the Z safety features weren't missing. The crash structures saved you from being injured more severely. Were those worn tires a factor in the spin before the crash? It might not be a stretch to say that car gave its usable life for yours.

pouchonnet

I wouldn't say it saved my life but the Z definitely handled that crash amazingly well which is one the reason i'm hesitating buying a 300zx which has older technology/safety. My tires we're pretty bad but i hit a spot of ice on the top of a hill (couldn't see it). Good tires or not i think i was donezo the way i was driving

RedlineHR

iTrader: (1)

Sorry to hear about your misfortune. Glad you're ok. Look for a nice HR and do breathing mods/tune and some decent suspension. That's all z's are missing. Put some studded snow tires on your stockers and nice tires on your cool set.

I am happy to see you take full ownership for the accident and honesty about what happened. It's refreshing. Let us know what you do next...

pouchonnet

I wish I could afford an HR but they are really expensive where I live because cars like those are stored for 6 months per year so the mileage is pretty low. They are around 15k-20k CAD. I've heard good things about 300zx but who knows, i might end up with a sentra

Thanks for your comments brotha