CAJUN KEN

Need some advise about a high speed wobble on a 09 Z06. Car has been lowered and I am running PSS tires.

Mordeth

What is the DOT date code on the MPSS? There was a bad batch around 2012 that causes this wobble. Happened to mine at the track at around 140mph. New tires fixed it.

Also check the alignment, axle nuts, lug nuts, tire pressure.

STANG KILLA SS

have your read up on the aero lift of the C6 Z06?

CAJUN KEN

Not sure about the tire date code.

CAJUN KEN

No, Don't know anything about aero lift. Going to the alignment shop Friday to have things checked out. I've read a lot of bad things about the MPSS tires,

Mordeth

It is on the side of the tire. Will say "DOT" and then some numbers. At the end are 4 numbers. For example it might say 1612. Which means it was made in the 16th week of 2012. So go look at them.

CAJUN KEN

Thanks, Will do after work.

TXGS507

I am running the MPSS's up front and the CupII's out back... Nothing but smooooth sailing... As Mordeath said, check the DOT codes... Alignment won't help if those codes reflect one of the bad years of production.

AzDave47

Aero lift on stock C6 Z06 with good alignment is modest and no control problems at 190+ MPH. I have over 400 miles at 150+ with stock aero, much on cruise control. Far better control than 60's-70's muscle cars at 100 MPH.

Cha_Cha

Up the pressure on the tires to 34psi cold. Seems to eliminate nasty wobble I got on the MPSS. I do also recommended becoming buddies with alignment shop to be sure that isnt what your chasing.

Les

Listen to this man- he knows what he's talking about. I had the same problem with the same tires, manufactured during that time span. I re-torqued the axle nuts, had the alignment checked, and had the tires re-balanced. No improvement. Then I opened a claim with Michelin and took the tires to Discount Tire where I bought them. They measured tread depth and gave me a great price break on a new set. Problem solved.

If your DOT code puts you in that time window I'd just call Michelin directly to discuss it. They were very good about helping me out but I read another guy's tale here where they didn't help him. However, he told them he was tracking his car and that's probably what made the difference.

CAJUN KEN

Cant wait to check the date code when I get home.
What about the lowering bolts being uneven, will that affect the corner weight of the car and possibly cause the wobble?

LS1Andrew

Same issue here, and I can almost guarantee that's what you are experiencing.

My new set of MPSS have been great. Wobble instantly removed by swapping tires.

Good luck! Hope you can get a partial discount back.

long_tall_texan

Here is another thing that may be causing the problem. I ran into this with mine after lowering. I lowered all the way down in front and back on stock bolts. Took it in for a re-alignment after lowering. After that, I would get pretty squirrely around the 100 MPH mark. Rear would start wobbling. Alignment re-checked, and it was good. After a lot of reading, I found a useful tidbit regarding the proper rake angle for correct aero. Front should be 1/4 inch lower than rear. Side to side should be within 1/16 inch. Measure front from the ground to bottom of rocker right behind front tire. Measure rear from ground to bottom of rocker just in front of rear tire. I found that mine was practically even / flat front to back, and had a little side to side variation too. I adjusted the side to side to be as close to even as I could, and set the front to rear right at 1/4" rake. Wobble went away immediately. I still took it back for a re-alignment again after changing ride height, but the proper rake fixed the wobble for me. Mine was on brand new Michelin PSS tires at the time.

CAJUN KEN

Thanks, That's definitely something to look at.

C 5

I had an issue with MPSS couple years ago. It would get a bad wobble when the driveline got jolted at WOT. Happened when you upshift hard, or hit an expansion joint, etc. felt like slickwalk. I ended up switching shocks, getting an alignment, messing with endless tire pressure settings,nothing worked. Then I switched my rear tires and it went away. Not to say the MPSS are bad tires, I have them on every vehicle, they are about the best street tire money can buy. Just a bad batch set. Contact Michelin (they have an amazing service) and they may cover you.

CAJUN KEN

What's weird is it has only done it those couple of times at hard acceleration. Brought it up to 145 mph yesterday slowly with no problems. Pretty scary not knowing if you'll get a wobble at that speed.

AzDave47

Scary knowing you will get that problem at that speed with MT ET SS 325/30-19's in the half mile. I know I won't run those MTs in the mile or 1 1/2 mile events.

FNBADAZ06

I think I'm going to get the R888R's for the 1/2 mile events. I might event run my Hoosier R7's as they are considerably lighter than the R888R's in the same size

CAJUN KEN

Did that happen to you?