rikhek

I like Buttonwillow. I've raced there in my GT1 997.2 911T. Fun track.

I'm friends with Randy and have raced against him in the same Porsche class the last 2 years. Most recently a PCA race at Sebring. He watched the video a number of times and his views are completely consistent with the comments made in this discussion. As has been mentioned several times in this thread he said the snap is the exact same thing that he experienced a number of times. He further stated aligning solved the problem.

One of the scary parts is it occurs randomly even on the same corner. Most times no problem while turning consistent laps and then on an arbitrary lap it surprises you.

As I stated in a prior post after aligning I've never experienced it in my 2015 or the 2017.

Rick

P.S. I've tried but can not beat Randy..... He's fast.

silver74vette

I only saw lateral acceleration on the PDR readout, In my opinion the weight shift was negligible front to back. The magnitude of the lateral acceleration was less than the previous left turn and should not have been an issue.

Once again, thanks for posting.

phantasms

Thank you for posting the video. Needless to say I must check my alignment now. I just had an alignment done at the dealer but I'm sure not up to par of what it should be. While making you able to take that turn, and others, at higher speeds have you found it make the car feel less twitchy and give you more confidence in it? Does the rear caster get knocked out of place with frequency or is it essentially set it and forget it?

Thank you again for posting I had never seen that before.

Best,
Gene

rikhek

Gene,

As stated in my posts above since I had my 2015 aligned post incident and now my aligned at 500 mile oil change 2017 on my dime I've not experienced this phenomena. Car now is confidence inspiring and performs at a world class level. It's a remarkable chassis, the problem is GM sends them out with **** alignment setups. Truly unacceptable.

A number of people have had movement with their eccentrics. Someone posted, I believe in this thread that they checked the torque on their eccentrics as delivered from the factory and they were significantly BELOW the recommended settings. Another quality control issue that just should not occur.

I haven't had my eccentrics move post alignment. My guy torques the bolts quite a bit past the recommended setting. We also mark their position with a paint pen to monitor for movement. A number of people have had movement with their eccentrics.

Rick

2fastnow

I think GM was overwhelmed with the success of the new car that they were 'caught off guard'. The alignment, paint issues is a sign of rushing them out. I've had Chevy's all my life, they run and don't brake easily.
That tranny problems are with who makes them for GM because CTS V's have no problems with those A8's.
I see the overheat as a over sight and will be fixed if not already at GM.

Edwardz

That area of road actually look very smooth and should not have been a problem at all. It did look like something was in the road at second 18 of the video but if you said you went back and looked maybe it was just a shadow or something. Even if it was tar or something on the road it should not cause the spin that far away. That spin came out of nowhere,you really weren't pushing it that hard at that moment. I think you said somewhere that your new car does not do the same thing and you've been on the same turn going faster?

Dabigsnake

OK, gotta admit, I did the same "snap around/ loss of traction on a curve" thing at Ron Fellows. At the end of my two days on our last time out, and it happened, almost as you see in rikheck video, but I was just pushing it a little more, as I was on the track. When I came in after my agriculture tour, myself and the instructor want to know what happened. He said, no way you were in comp 2 on PTM, I said....yes I was, and I've got it on PDR....well when we looked at it, sure enough, I had managed to have it in comp 2. ?? It just snapped on me, and I was driving no different than any other time. I immediately noticed that rikheck had his in comp 2 as well....coincidence? I think not!! I'm kinda scared on comp 2 now. Took me a while to get used to the stability control coming out of corners, but it can be used efficiently, you just can't let the back step out and counter steer usual with a no-nannie car. Try and push it and it starts babbling and shooting flames out the exhaust.(your are loading it up, but not burning all the fuel) Just go with it and unwind the steering to let it fully accelerate. Seems my '17 is acting differently so far with some street launches, seems to allow too much spin and shifts up when depending on traction control. I'll see how it does when I get on the track. I'll try and find that PDR video. I'm a Mac guy, so It's on my wife's windows.

thebishman

Personally I would not do this.

The car was designed for the tyres (MPSS or MPSC2's) and vice versa. Both tyres are incredibly well regarded, with the MPSS widely thought of as the best ultra-high performance summer tyre available. The SC2's can get you lap times fairly close to an R6(7) with the added benefit of being safe to drive to/from the track on.

Further, suspension, springs etc are going to act differently with the non-OEM tyre, especially one with a higher sidewall, and not having the super stiff inner sidewall which both Michelins do.

Perhaps the Nittos may 'perform' better in low(er) ambient temps, because for sure the 'grip' of the Michelins is a damn site better and more reproducible at 70dF than at <50dF. But that's the only negative I've found with the Michelins.

thebishman

I want to thank Rick for having the ***** to re-post the video of his snap oversteer condition here, even though he leaves himself open to criticism from certain knuckle draggers.

It is eye-opening for all owners, especially those just getting used to the car after a recent purchase, to see what can happen with a ***** alignment. And have no doubt about it, the way the car is delivered from the factory is absolutely no guarantee that it's got a decent alignment! I strongly recommend getting an alignment at the 500 mile oil/filter change service even if the car 'tracks straight' going down the highway! Make it a part of the negotiated deal when you buy the car; if not pay for it out of pocket as they aren't expensive, and lastly spend your money for service only at a dealership that invests the time and money; (by buying the right tools), to know how to align these tremendous cars.

Thanks again Rick; you've done us all a big service!

Bish

rbartick

Which mode is "Comp 2"? The video posted by Rick says "Sport 2", which mode is that?

dead of night

Shouldn't the manual say, "press and release the TCS/StabiliTrak button to turn off PTM and return "FROM" the traction control and StabiliTrak systems"?

In other words, press the button to go back to the driving modes Eco, Weather, Tour, etc.

rikhek

I guarantee there was NOTHING on the road. The shadows make it look like there is tar or oil or something, however, road was good. I spent a lot of time examining as I couldn't figure out what happened and thought it had to be something on the road.

Yes, I wasn't pushing at all, just cruising through the corner due to limited line of sight on corner entry through mid corner. I was such a surprise is was one of those WTF moments.

Since the incident and realignment I've navigated that corner in the 2015 that preiously spun and my 2017 right at 20 mph faster with no drama. Again note, I paid to have my 2017 aligned at my 500 mile change. I was way off on all alignment settings from the factory. The rear caster from the factory was 0.0 on one side and -0.8 on the other. All settings were within GM's "acceptable" range but nothing was symetrical. Caster on one side was negative and positive on the other, however, this is still with the acceptable range.

Pure nonsense.

rikhek

When in Race Mode as I was Sport 2 is synonymous with Perf Trac 4 as described on page 200 of the manual you posted above. I don't know why the manual and GM don't use consistent terminology. Three different terms are used for the same Race mode setting:

Sport 2 = Comp 2 = Perf Trac 4

For those wondering I was in Race Mode out in the country experimenting/testing the various race mode settings. I was getting a feel for the various levels of stability control intervention, e-dif characteristics, traction control performance, PTM, etc. I was not out there playing boy racer but rather learning the machine in a somewhat isolated, controlled environment on roads that I know very well.

I was NOT experimenting/pushing AT ALL on this particular corner due to limited line of sight. Hell, I probably only had one hand on the wheel and was taking a drink of beer with the other when it happened ;-)

EMINENT 1

Not that I would use it, but launch control isn't available on Z06 and Z51 with mag ride?

Crazy!

rbartick

Active handling and TC are both off in that mode. With that being said I'm not sure why dabigsnake posted that Ron Fellows couldn't explain why he spun in that mode.

Dabigsnake

But you are actually going back to where you started (normal driving modes) and left by pressing the button twice. Which is the normal driving modes that all have traction control and Stabilitrak on. eco, wet, touring, sport, etc

dead of night

Look, I want to be able to buy a C7 or Z06 and simply ask the dealership to check the alignment before I drive away.


If I have to do anything more than that, like purchase my own alignment tools to provide them to the dealer to get an appropriate alignment, it's beginning to seem like a deal breaker.


Is that unreasonable?

Mordeth

No it is not unreasonable. But it is simply how life works. I don't know about you, but nothing I have ever done of any consequence was easy, simple or reasonable. Not preaching, just saying.

If the alignment is important to you, and it should be, then tell your dealer that you won't buy the car until they have the appropriate tools to service it. If they refuse, then find another dealer. Simple stuff. And if you can't find another dealer local to you then you make the next decision. Find an alignment shop that can do it. Buy out of state and have shipped (with alignment done). Buy the tools yourself and loan them to the dealer. Don't buy the car. No reason at all to get worked up over these things. Nothing is ever easy. Sucks, but how it goes. We can sit here and complain or we can get things done. I'll do the latter, and I did.

Kyflyer

Heck, I will buy the tool for the dealer and leave it with him if he will do the alignment for me at no charge. I haven't checked with him, but I imagine he will already have it as he is our club sponsor and there are several C7 Z06s in the club. I will also ask the other owners what they have done, one is a very competitive racer and the next time I see him I will ask him about this. I am new to the Z06 family and this thread has been a great resource for me. Now if someone will manufacture a decent non runflat all season tire for street use I will be a happily satisfied Z06 owner. I will keep the runflats for track use, but 99% of my driving will be street driving.

rikhek

Guys,

Not to belabor the point but simply asking a dealer to "check" your alignment will typically be an exercise in futility!!! I can't state this strongly enough.

GM allows a WIDE range of "acceptable" settings and does not require symmetry. Look up above at Post #180 of the acceptable alignment specifications for our cars provided by Bill. A dealer can check and say "you're good to go buddy" with the settings below as they are within range:

Left front caster: +8.0
Rear front caster: -8.0

Left rear caster: +0.8
Right rear caste: -0.8

Left front camber: 0.0
Right front camber: -1.5

Left rear camber: -0.5
Right rear camber: -1.7

Etc, etc, etc....

This wide range of acceptable settings is why they come set all out of wack from the factory.

The dealer techs are not used to aligning performance cars. They're used to aligning pickups, Cruz's, Malibu's, etc. As long as the alignment heads indicate green (i.e., the settings are within the WIDE range of acceptable settings) they're generally not going to mess with it. Hell, I've had a number of dealer techs chuckle at me and state the rear caster is not adjustable.

I urge you to talk to the man who's going to "check" your alignment and question him to determine if he's knowledgeable. Also, you MUST provide him in writing the EXACT settings you want on the car. You must be convinced he understands the importance of setting the rear caster where you want as NO alignment machine provides this reading on the printout sheet. You have to trust him or be there to observe the setting for yourself. Of course, you must tell him you want a copy of the final settings on the alignment printout sheet.

Not meaning to preach to you all or talk down but this is really important stuff. It's such a big deal I had no problem paying out of my pocket to get my new 2017 "properly" aligned to the EXACT Levitas/TPC Racing specs provided in this thread at my 500 mile oil change. I'm lucky enough to have a tech who is a fellow racer and takes great pride in his work. He gets it right, unlike the majority.

Rick