Death Wobble Under Hard Acceleration....New tires fixed her though. - Camaro5 Chevy Camaro Forum / Camaro ZL1, SS and V6 Forums

R1jamn · 07-29-2019, 01:14 AM

Last December I picked up a low mileage 2015 ZL1 and the previous owner had installed All Season Toyo Proxes 4 Plus tires and the "Aspect Ratio" on these were not OEM spec.
The rears are 315/35 and the fronts were 275/40. These tires were brand new.

Well I just recently started driving this car and got thru it's break in period and was finally able to open her up.
The very first time I opened her up was on the hwy and the front end pulled extremely hard to the left.
I compensated and then ended up in a wobble.
This was not fun, nor did I consider this to be the norm for this vehicle as the rear tires did not break loose.
The tire pressures were all at 32 psi. Seat of the pants alignment did not suggest an alignment issue.
I kept testing her and the results were always the same. A sharp strong pull to the left like a sudden tram lining effect was taking over.
It didn't matter if I was in Tour or Sport mode. The results were always the same.

So after 1200 miles of "This is not going to end well", I changed out just the front tires for some with the OEM aspect ratio (285/35).
I scrubbed the new tires in today and went out for a test.
The results were absolutely amazing.
She tracks laser straight now under hard acceleration and handled the curves of Hwy 90 like I was on rails.
Great feedback and less road noise too. Completely confident now and extremely relieved that I have a healthy ZL1 (except for Mylink issues).

Not sure what was causing the pulling.
Was StabiliTraK kicking on because of the incorrect aspect ratio? I wasn't looking for a StabiliTrak light but it may have come on.
Was it just a bad tire compound of the Toyo Proxes?
A combination of both?

So the new tires I installed were the new Continental Extreme Contact Sport.
These have a tread wear rating of 340. Not quite as soft as the Goodyear Eagle F1's and not as hard as the Toyo Proxes that I removed.

I will be installing the Continentals on the rear next week. They look good too.

CamaroFred · 07-29-2019, 02:55 AM

It wasn't the tire sizes as the 315/35 are exactly the same radius as the 275/40s.
Your 285/35s are now ~3% smaller than the 315/35s. Still within ABS/ST specs, AFAIK.
Had to be a damaged tire.

Easy fix though, I'm glad you guessed right!
The Continentals have been tested and found to be excellent by many.

R1jamn · 07-29-2019, 05:04 AM

Quote:

Originally Posted by CamaroFred

It wasn't the tire sizes as the 315/35 are exactly the same radius as the 275/40s.
Your 285/35s are now ~3% smaller than the 315/35s. Still within ABS/ST specs, AFAIK.
Had to be a damaged tire.

Easy fix though, I'm glad you guessed right!
The Continentals have been tested and found to be excellent by many.

Good morning Fred.
True, the Toyo's are the exact same size radially.
However, the Goodyear Eagle F1's that come stock on the ZL1 are 1.75% different radially.
The set-up now with the Continental front and Toyo rear are 2.75% different radially and closer to the OEM set-up of the Goodyears.

Not sure how these cars are programmed or how forgiving they are when it comes to having different aspect ratios that are not the same as OEM specs.
My ZL1 certainly did not agree with it.

I'll be exactly at OEM specs as soon as I get the Continentals on the rear.
Looking forward to testing again.

silversleeper · 07-29-2019, 02:37 PM

Sounds like a bad tire. Did you have the car trailered when you bought it?

R1jamn · 07-29-2019, 03:13 PM

Quote:

Originally Posted by silversleeper

Sounds like a bad tire. Did you have the car trailered when you bought it?

Yes, I had it trailered out to me.

silversleeper · 07-29-2019, 04:23 PM

Quote:

Originally Posted by R1jamn

Yes, I had it trailered out to me.

Seen this happen, not from sitting flat on a surface, but rails that stick up, angle iron type things that tires might run up on or sit on during transport. Or strapping down methods on the tires.
Of course potholes can do this too, but my bet goes to the trailering, which is why I asked.

Edit: Since it could be a pothole or defective tire I'm not asking you to callout the trailering folks. They could be awsome and it was something else.

R1jamn · 07-29-2019, 05:32 PM

Quote:

Originally Posted by silversleeper

Seen this happen, not from sitting flat on a surface, but rails that stick up, angle iron type things that tires might run up on or sit on during transport. Or strapping down methods on the tires.
Of course potholes can do this too, but my bet goes to the trailering, which is why I asked.

Edit: Since it could be a pothole or defective tire I'm not asking you to callout the trailering folks. They could be awsome and it was something else.

The ride quality was good no matter what speed I was cruising at.
Everything felt fine if my acceleration was steady and gradual.
It was only an issue when accelerating hard. The front would jerk to the left just like a tramlining effect.

NZZL1 · 07-30-2019, 02:56 AM

Rear trailing arms deflecting? It's a common issue when launching hard or with load applied.

R1jamn · 07-30-2019, 05:17 AM

The sharp pulling was during hard acceleration when I was already at hwy speeds.
I never tested it from a dead stop or on city streets.

yellow69z28rs · 07-30-2019, 11:20 PM

Common issue.
Dangerous.
Tire change fixes it......But it will come back

silversleeper · 07-30-2019, 11:55 PM

Doesn't sound like a tire if only on acceleration. Deflection, bent part or alignment?

RobZL1 · 07-31-2019, 10:16 AM

Quote:

Originally Posted by yellow69z28rs

Common issue.
Dangerous.
Tire change fixes it......But it will come back

So what's the root cause then?

R1jamn · 08-01-2019, 06:07 AM

Quote:

Originally Posted by silversleeper

Doesn't sound like a tire if only on acceleration. Deflection, bent part or alignment?

I still believe it had something to do with the incorrect aspect ratio of the tires.
Traction Control or StabiliTrak is still my guess.

R1jamn · 08-06-2019, 03:22 PM

Had the Continental Extreme Contact Sport tires installed on the rear (305/35/ZR20).

I scrubbed them in and tested her out again. Everything is good.
At hwy speeds and under hard acceleration (passing gear) she performed flawlessly.
No tramlining or sudden jerks to the left which had me in a death wobble before.

I felt confident to explore and try the driving modes.
I was surprised to find out that all PTM modes (1 thru 5) still have Traction Control engaged.

Turning the nannies off gives the ZL1 a completely different power delivery. What a beast.
I am extremely relieved that changing the tires back to the OEM aspect ratio's have cleared up the death wobble issue.

07-29-2019, 01:14 AM	#1
R1jamn Drives: 2015 ZL1, 2023 ZL1, 2014 Raptor Join Date: Sep 2011 Location: New Mexico Posts: 94	Death Wobble Under Hard Acceleration....New tires fixed her though. Last December I picked up a low mileage 2015 ZL1 and the previous owner had installed All Season Toyo Proxes 4 Plus tires and the "Aspect Ratio" on these were not OEM spec. The rears are 315/35 and the fronts were 275/40. These tires were brand new. Well I just recently started driving this car and got thru it's break in period and was finally able to open her up. The very first time I opened her up was on the hwy and the front end pulled extremely hard to the left. I compensated and then ended up in a wobble. This was not fun, nor did I consider this to be the norm for this vehicle as the rear tires did not break loose. The tire pressures were all at 32 psi. Seat of the pants alignment did not suggest an alignment issue. I kept testing her and the results were always the same. A sharp strong pull to the left like a sudden tram lining effect was taking over. It didn't matter if I was in Tour or Sport mode. The results were always the same. So after 1200 miles of "This is not going to end well", I changed out just the front tires for some with the OEM aspect ratio (285/35). I scrubbed the new tires in today and went out for a test. The results were absolutely amazing. She tracks laser straight now under hard acceleration and handled the curves of Hwy 90 like I was on rails. Great feedback and less road noise too. Completely confident now and extremely relieved that I have a healthy ZL1 (except for Mylink issues). Not sure what was causing the pulling. Was StabiliTraK kicking on because of the incorrect aspect ratio? I wasn't looking for a StabiliTrak light but it may have come on. Was it just a bad tire compound of the Toyo Proxes? A combination of both? So the new tires I installed were the new Continental Extreme Contact Sport. These have a tread wear rating of 340. Not quite as soft as the Goodyear Eagle F1's and not as hard as the Toyo Proxes that I removed. I will be installing the Continentals on the rear next week. They look good too. Attached Images Last edited by R1jamn; 07-29-2019 at 02:56 AM.

07-29-2019, 02:55 AM	#2
CamaroFred Drives: Miss Con Ception Join Date: Aug 2016 Location: Chicagoland Posts: 2,998	It wasn't the tire sizes as the 315/35 are exactly the same radius as the 275/40s. Your 285/35s are now ~3% smaller than the 315/35s. Still within ABS/ST specs, AFAIK. Had to be a damaged tire. Easy fix though, I'm glad you guessed right! The Continentals have been tested and found to be excellent by many. __________________ 2011 1SS/RS LS3 CGM

07-30-2019, 11:20 PM	#10
yellow69z28rs Drives: 2013 ZL1 Convertible Black Join Date: Nov 2012 Location: Alexandria La. Posts: 363	Common issue. Dangerous. Tire change fixes it......But it will come back __________________ JRE 750 HP package Rag Top Rob

08-06-2019, 03:22 PM	#14
R1jamn Drives: 2015 ZL1, 2023 ZL1, 2014 Raptor Join Date: Sep 2011 Location: New Mexico Posts: 94	Had the Continental Extreme Contact Sport tires installed on the rear (305/35/ZR20). I scrubbed them in and tested her out again. Everything is good. At hwy speeds and under hard acceleration (passing gear) she performed flawlessly. No tramlining or sudden jerks to the left which had me in a death wobble before. I felt confident to explore and try the driving modes. I was surprised to find out that all PTM modes (1 thru 5) still have Traction Control engaged. Turning the nannies off gives the ZL1 a completely different power delivery. What a beast. I am extremely relieved that changing the tires back to the OEM aspect ratio's have cleared up the death wobble issue. Attached Images

07-29-2019, 02:37 PM	#4
silversleeper Big Crow Drives: '13 ZL1 Join Date: Mar 2017 Location: California Posts: 1,487	Sounds like a bad tire. Did you have the car trailered when you bought it?

07-30-2019, 02:56 AM	#8
NZZL1 Drives: 2013 BRM ZL1 Camaro M6 Join Date: Feb 2014 Location: Auckland, New Zealand Posts: 160 View My Garage	Rear trailing arms deflecting? It's a common issue when launching hard or with load applied.

07-30-2019, 05:17 AM	#9
R1jamn Drives: 2015 ZL1, 2023 ZL1, 2014 Raptor Join Date: Sep 2011 Location: New Mexico Posts: 94	The sharp pulling was during hard acceleration when I was already at hwy speeds. I never tested it from a dead stop or on city streets.

07-30-2019, 11:55 PM	#11
silversleeper Big Crow Drives: '13 ZL1 Join Date: Mar 2017 Location: California Posts: 1,487	Doesn't sound like a tire if only on acceleration. Deflection, bent part or alignment?