CT5-V Blackwing: Slight Yaw/Rotation under hard throttle

[quikag]

I'll preface this with the statement that I am familiar with higher horsepower cars having owned a C6 ZR1 for 12 years now, the last two years modified to power levels significantly above my 5BW and I've tracked my cars for many years.

So, I've had my 5BW over 14 months now with about 7k miles on her. Love her to death and it's an amazing car. Only minor issue I've had is how the back end gets a little squirrelly under heavy throttle in lower gears, especially with this cooler weather we've been having in Texas.

What I mean is the back end walks around a bit under hard throttle. Could be slight slopes and/or crowns in the roads, but car seems to rotate a bit back and forth under power more than my ZR1.

Is it chassis/suspension geometry set-up or something odd the e-diff is doing? Is it the relatively smaller 305 tires? For example yesterday, I turned traction control off as I U-turned. Then when the car was straight, I nailed it in first, it spun up hard and I shifted to second, tires spun up again and car started to rotate a bit while I'm basically doing 60mph at this point. I lift a bit to regain control and car does a small "tank slapper" and snaps back into line and all is good. It's a little disconcerting as the car doesn't always want to stay straight when spinning.

I'm not saying this is a major issue, but I'd like for it be a little more stable under hard throttle when the tires are spinning. Any way to adjust e-diff or any other setting to try to take this down a bit? Or is it just the way this car is? If so, I'm not that stressed about it, but it would be nice if it hooked better in 1st and 2nd.

 

[Throat Yogurt]

I'll preface this with the statement that I am familiar with higher horsepower cars having owned a C6 ZR1 for 12 years now, the last two years modified to power levels significantly above my 5BW and I've tracked my cars for many years.

So, I've had my 5BW over 14 months now with about 7k miles on her. Love her to death and it's an amazing car. Only minor issue I've had is how the back end gets a little squirrelly under heavy throttle in lower gears, especially with this cooler weather we've been having in Texas.

What I mean is the back end walks around a bit under hard throttle. Could be slight slopes and/or crowns in the roads, but car seems to rotate a bit back and forth under power more than my ZR1.

Is it chassis/suspension geometry set-up or something odd the e-diff is doing? Is it the relatively smaller 305 tires? For example yesterday, I turned traction control off as I U-turned. Then when the car was straight, I nailed it in first, it spun up hard and I shifted to second, tires spun up again and car started to rotate a bit while I'm basically doing 60mph at this point. I lift a bit to regain control and car does a small "tank slapper" and snaps back into line and all is good. It's a little disconcerting as the car doesn't always want to stay straight when spinning.

I'm not saying this is a major issue, but I'd like for it be a little more stable under hard throttle when the tires are spinning. Any way to adjust e-diff or any other setting to try to take this down a bit? Or is it just the way this car is? If so, I'm not that stressed about it, but it would be nice if it hooked better in 1st and 2nd.

Did you have PTM turned on? Give that a try.

 

[dwgcooks]

I Would look at your cradle and suspension arm bushings. Also look at ZL1 message boards for what they do for better rear end feel.

 

[SIX 40]

My V3 did this under hard throttle. I rather enjoyed it, though. Some people say it's the tires, some say alignment and some have changed their suspension arm bushings as mentioned above. Good luck!

 

[565565]

Mine does the same thing for what it's worth. I think it must be traction related because it doesn't do it when it's warm out and not in the higher gears. Like you said it's not spinning, but feels like the rear is yawing a bit. I wonder if it's like you said the diff shunting power around looking for traction on colder days. These days I'm really pushing what the PS4S tires are meant for (30 degree temps)

That said I think it hooks way better than you would expect a 668hp car with 305 tires should. For example it hooks up better than my 405 c5 z06 with 295 tires does.

 

[jbawden]

I think its probably a combo of over +50 ft.lbs. more torque at a few hundred lower RPM and a curb weight is what, 800lbs more in the BW? Then pile on with the smaller width tires in cool weather and its just the BW doing BW things.

My SS behaved the same in cool weather when the OEM Bridgestones were aging out.

 

[quikag]

Thanks all! I will try the PTM modes to see if it regulates the torque a touch better. Yes, it really only does it in cooler weather in lower gears and it likely is just a byproduct of all that power looking for a nice, warm, comfy place to call home on the tarmac and not finding it.

I do agree that overall it does put the power down great. I'm not complaining as I'd rather have too much power than not enough for sure.

 

[jumpmanjay]

It definitely makes it interesting. Even accelerating hard on the freeway and it feels like you're riding a bull holding on for dear life.

 

[PrimeTime]

Yep, mine does the same! Love it! Let off and throttle back in! "Caught in the chaos" folks just look at me like WTF is that? It's a Blackwing.

 

[Tall Steve]

I know its not the same but with the "cooler" weather my 4 started get squirrely lately... I chalked it up to the tire....

 

[poor-sha]

Check the rear toe. You want around 3mm toe in on each side. I had originally messed up my rear toe and had toe out in the rear. You could feel the back end moving around under heavy throttle.

 

[rdollie]

Hmmm...shouldn't be quite that noticeable in my experience. By cooler weather, what temps are we talking? Keep in mind the stock tires have a lot (I read 61%) of the Cup 2 polymer so they're going to lose traction with air temps in the 40s. I know from my 5Bw and V3 CTS-V that these cars tramline with any crown in the road as well.

 

[Tall Steve]

Hmmm...shouldn't be quite that noticeable in my experience. By cooler weather, what temps are we talking? Keep in mind the stock tires have a lot (I read 61%) of the Cup 2 polymer so they're going to lose traction with air temps in the 40s. I know from my 5Bw and V3 CTS-V that these cars tramline with any crown in the road as well.

It's been in the 40/50's in Texas lately...

 

[Speed Racer 007]

Sounds like it's the lack of T/C and the car just doing its thing. When I spoke with a caddy engineer a few months back he was explaining how the ECU adjusts timing/fuel, etc., in various settings and gets more involved with use of the PCM.

When I had my '14 cammed/built GT500 (845 WHP/Race tune) I would love to turn all the nanny's off and spin my 315's/R888's while going through 3rd gear at 100+. With 760 lbs of tq she would basically lite em up at will but went straight down the road. She was a badass bitch I tell ya.. LOL

 

[RDATLTE]

I Would look at your cradle and suspension arm bushings. Also look at ZL1 message boards for what they do for better rear end feel.

The answer there is the solid bushings from the ZL1 1LE.

 

[pkincy]

I got the same feel in both my ATS-V and the 4BW. It is not a feel I got in the C7Z06. I have always felt it was the EDiff fighting to keep both wheels with traction. In my case the rear is not breaking loose, it is just a bit of wander from the rear both right and left. It was a bit disconcerting at first because it was not something I was used to from the Corvette.

 

[Andi]

I'll preface this with the statement that I am familiar with higher horsepower cars having owned a C6 ZR1 for 12 years now, the last two years modified to power levels significantly above my 5BW and I've tracked my cars for many years.

So, I've had my 5BW over 14 months now with about 7k miles on her. Love her to death and it's an amazing car. Only minor issue I've had is how the back end gets a little squirrelly under heavy throttle in lower gears, especially with this cooler weather we've been having in Texas.

What I mean is the back end walks around a bit under hard throttle. Could be slight slopes and/or crowns in the roads, but car seems to rotate a bit back and forth under power more than my ZR1.

Is it chassis/suspension geometry set-up or something odd the e-diff is doing? Is it the relatively smaller 305 tires? For example yesterday, I turned traction control off as I U-turned. Then when the car was straight, I nailed it in first, it spun up hard and I shifted to second, tires spun up again and car started to rotate a bit while I'm basically doing 60mph at this point. I lift a bit to regain control and car does a small "tank slapper" and snaps back into line and all is good. It's a little disconcerting as the car doesn't always want to stay straight when spinning.

I'm not saying this is a major issue, but I'd like for it be a little more stable under hard throttle when the tires are spinning. Any way to adjust e-diff or any other setting to try to take this down a bit? Or is it just the way this car is? If so, I'm not that stressed about it, but it would be nice if it hooked better in 1st and 2nd.

You ever notice how much the shifter moves over bumps just cruising around town? My uneducated guess is they had to put some pretty squishy bushings in the drivetrain and subframe mounts to get it to pass Cadillac NVH standards. Your wheel alignment is probably deflecting like that shifter in high torque / shock load situations.

 

[theprototype]

Im in Houston and it’s been a while since I’ve driven in cold weather like this. Was wondering how I shot through these tires in only 2500 miles but it’s totally the cold weather effect on the compound. Been a few years since i lived in Oklahoma, all the memories now coming back!

 

[quikag]

You ever notice how much the shifter moves over bumps just cruising around town? My uneducated guess is they had to put some pretty squishy bushings in the drivetrain and subframe mounts to get it to pass Cadillac NVH standards. Your wheel alignment is probably deflecting like that shifter in high torque / shock load situations.

You are a genius, Andi! (literally).

That does make a lot of sense. Again, it's not a major issue, but the rear end definitely does walk around a bit more than I'd prefer.

That comment above about using the ZL1/1LE bushings might be a good idea after someone more technical than me validates it.

 

[copperpenny]

I'll preface this with the statement that I am familiar with higher horsepower cars having owned a C6 ZR1 for 12 years now, the last two years modified to power levels significantly above my 5BW and I've tracked my cars for many years.

So, I've had my 5BW over 14 months now with about 7k miles on her. Love her to death and it's an amazing car. Only minor issue I've had is how the back end gets a little squirrelly under heavy throttle in lower gears, especially with this cooler weather we've been having in Texas.

What I mean is the back end walks around a bit under hard throttle. Could be slight slopes and/or crowns in the roads, but car seems to rotate a bit back and forth under power more than my ZR1.

Is it chassis/suspension geometry set-up or something odd the e-diff is doing? Is it the relatively smaller 305 tires? For example yesterday, I turned traction control off as I U-turned. Then when the car was straight, I nailed it in first, it spun up hard and I shifted to second, tires spun up again and car started to rotate a bit while I'm basically doing 60mph at this point. I lift a bit to regain control and car does a small "tank slapper" and snaps back into line and all is good. It's a little disconcerting as the car doesn't always want to stay straight when spinning.

I'm not saying this is a major issue, but I'd like for it be a little more stable under hard throttle when the tires are spinning. Any way to adjust e-diff or any other setting to try to take this down a bit? Or is it just the way this car is? If so, I'm not that stressed about it, but it would be nice if it hooked better in 1st and 2nd.

I had the same concerning feeling from day 1. I have tracked two other Blackwing 5s and it is not a characteristic of the vehicle. After getting home from Spring Mountain, I took my car directly to the dealer and the rear toe was "way off". Problem is solved, it feels so much safer!