Death Wobble Under Hard Acceleration....New tires fixed her though.

[RobZL1]

I think the original tires must have had a defect. I run a 275/40 and 315/35 with no issues. I can put it to the floor from 1750rpm to 6700rpm in 3rd and 4th with no issues. I don't think the aspect ratios had anything to do with your particular issue.

[R1jamn]

Originally Posted by RobZL1

I think the original tires must have had a defect. I run a 275/40 and 315/35 with no issues. I can put it to the floor from 1750rpm to 6700rpm in 3rd and 4th with no issues. I don't think the aspect ratios had anything to do with your particular issue.

Hmmm....Well Damn....It felt like the Stabilitrak activating and braking the front left wheel causing the sudden pull to the left.
I just don't see a defective tire causing this as they were never an issue when taking corners or everyday driving.
The only thing I notice now is the Traction Control kicking on and cutting throttle under hard acceleration, which is normal for the ZL1.
Tracks straight as a laser after replacing the front tires. The new rear tires did not have an impact when testing.

[CamaroFred]

I think it is unlikely that ST would brake only the left front. From my experience it would brake the RR at the same time.
I believe ST uses the lateral G force and compares it to steering input. When they are at odds (steering into a slide) it attempts to straighten the vehicle.
At least that's what happened the few times I encountered it.
As for ABS, that should only activate when a wheel speed sensor detects a lock-up (or impending lock-up) and pulsates the pistons. Many professional drivers use ABS to their advantage when the rules allow.

ABS, ST, and TC have indicators on the dash so you can see when they activate.

But, who knows what the engineers have really put into the software?

[R1jamn]

Originally Posted by CamaroFred

I think it is unlikely that ST would brake only the left front. From my experience it would brake the RR at the same time.
I believe ST uses the lateral G force and compares it to steering input. When they are at odds (steering into a slide) it attempts to straighten the vehicle.
At least that's what happened the few times I encountered it.
As for ABS, that should only activate when a wheel speed sensor detects a lock-up (or impending lock-up) and pulsates the pistons. Many professional drivers use ABS to their advantage when the rules allow.

ABS, ST, and TC have indicators on the dash so you can see when they activate.

But, who knows what the engineers have really put into the software?

Stabilitrak will brake an individual wheel based on steering input vs the vehicles actual response. See diagram.
Braking two wheels at the same time is counter intuitive to StabiliTrak programming.
But you're correct Fred. We know not how the engineers have programmed this.
I see the need to get this ZL1 on a lift and remove the belly pan and take a good look at the steering components and suspension linkages for any evidence of damage or damage repair.
After changing the tires this thing is now responding as I would expect it to.
I'll update when I get "professional" to take a look underneath it.

To add: The Toyo Proxes 4 Plus that I removed are not performance tires so perhaps I was breaking traction. Never got sideways at all though.

[silversleeper]

Yeah could be stailitrak ? In hindsight would have been intersting to try to let air out of the rear tires and do it again to improve traction. Also to go pure track mode with everything disabled.
My bike wouldn't wheelie easy with the much acclaimed Battleaxe tires and I didn't notice any slipping. I replaced them with better tires and it wheelied easily. If they don't make squeeling noise or slip enough to fishtail you can't tell.
One rear tire slipping more than the other...kicking in the stabilitrak to the left.

[R1jamn]

Originally Posted by silversleeper

Yeah could be stailitrak ? In hindsight would have been intersting to try to let air out of the rear tires and do it again to improve traction. Also to go pure track mode with everything disabled.

This is so true.
In hindsight I should have tested this theory by turning off all of the electronic nannies by pushing and holding down the active management button.
It pulled hard left when I tested in Tour, Sport and PTM 2 and 3. I don't believe I tested PTM 4 and 5. I certainly didn't test it with all the nannies off.

I made an appointment to have the alignment checked and the front suspension/steering components inspected.
Unfortunately it's three weeks out. This guy is busy.

[R1jamn]

Update:

I changed the oil and filter today and had a good look at the steering and suspension.
Everything was good. Nothing bent, dinged, or scuffed.
All wheel speed sensors where in good shape too as well as the drive shaft.

I had set up an appointment to get the front end alignment checked but canceled because 3 weeks out is just not reasonable.
So...I scheduled an appointment with another shop that will check it within a couple of days from now.
I will update the results.

Pics of wheel speed sensors and linkages.

[yellow69z28rs]

Update?

[DRKS1D3]

To this day, I'm still trying to figure out what the thought process is when putting All-Season tires on a high hp, high performance car, such as the ZL1. It is the same as Dodge putting A-S tires on the Hellcat from the factory and if you want High Performance Summer tires...it is an option where you have to pay extra. We are talking about vehicles that are made to outright perform and people are throwing A-S tires on them? My DD (Chevy Cruze) comes with A-S tires. I would expect them to be on a ~150hp commuter car, not on a 600hp+ track monster.

To each their own I suppose. OP, The Continentals look great and I'm sure you'll get performance and tread wear that you're looking for.

[RobZL1]

Well, people do different things with their cars. I wanted an 800rwhp daily driver. I've had play cars that never saw rain. I'm doing it differently this time. It's been much more fun this way in my opinion. Oh, and I wanted A/S tires because I don't want to pay $1500 every year for new tires. Also, there's this:

[DRKS1D3]

Originally Posted by RobZL1

Well, people do different things with their cars. I wanted an 800rwhp daily driver. I've had play cars that never saw rain. I'm doing it differently this time. It's been much more fun this way in my opinion. Oh, and I wanted A/S tires because I don't want to pay $1500 every year for new tires. Also, there's this:

Enjoy!!!

[RobZL1]

Originally Posted by DRKS1D3

Enjoy!!!

I'm all smiles every day because I get to enjoy this thing.

[DRKS1D3]

Originally Posted by RobZL1

I'm all smiles every day because I get to enjoy this thing.

If you're having fun, that is all that matters! You're the one that is paying your bills. Use it as you see fit. Enjoy!

[R1jamn]

Had the alignment checked today at two different shops.

Shop 1 checked and adjusted the alignment (Clarks). They adjusted the front toe a very small amount.

Test drove her for 100 miles and re-checked the alignment at a different shop.
The test drive was great. Stabilitrak did not intervene when hard on the throttle when already at hwy speeds.
Again, this ZL1 tracks laser straight after replacing the front tires. I didn't notice any type of change after the alignment.

Shop 2 re-checked and verified that the alignment was good. They did not make any adjustments (Les Schwab).

It's was a good day!