Hi all, I think... or thought I might want to pick up a Grand Sport after getting the itch to drive something with more oomph at the track. I used to track a GT350, but now have a '97 M3 and its tons of fun. I took a ride in a spec C5 and really enjoyed that so I started looking into vettes. The closest I have gotten is my current daily a gen3 ctsV. On paper the GS seems to have it all (wheel cracking aside) and so I went and test drove a 7MT with 30k on the odo. I have to say I am kinda whelmed. It felt like the front was a bit wallow-y and it floated around (I am sure the fact it is on run flats contributes to that a lot) However the main thing I came away not liking was that the throttle seemed very inconsistent. Either it was a low % open, or WOT it never felt like a linear delivery at anything other than WOT. Is there a mode which has a more linear throttle mapping? Is it worth it to grab a Z51 stingray instead? The dry sump + GS specs just look so good but I didn't feel the car was as composed as say my GT350 was.

 

Z51 is a package for the base stingray a GS already has the Z51 package it's just not called that on the GS it's standard. I'm surprised, my GS blows me away with handling. Maybe there is an issue with the one you drove. It comes with a track alignment which I changed for better tire wear, still handles great. 50/50 weight distribution super ridged frame corners like it on rails. I would test drive another one just to be sure I'm just surprised to hear this.

 

I agree totally with Punisher44. My GS is totally predictable and corners amazingly. I sold an '04 Z06 to get the GS. GS is quicker, faster and pulls more G's in the turns. In my case, the top also goes down. Loving every minute of the "Miles of Smiles".

 

I think I am going to do that. I test drove this one in particular because it was at carmax and they don't make a big deal about the car being test driven. It has a few accidents in its past and when I looked at it up close ... woof I wouldn't trust it but figured it can't be so bad off that it would be a bad experience. Maybe I assumed too much there. I'll bide my time, I really would love one in the dark red color.

 

Look into a soler throttle body. Fixed my issues with the terrible throttle response.

 

I think the GS had issues! I have never heard anyone I know complain about the GS handling.

 

Order and drive another one as suggested.
Carmax in my experience so far has been great but if you're not careful, you will end up with a car that someone dumped there and they just make it look pretty and not necessarily road worthy.
I have bought 2 C7s already from them that I returned due to ride quality and suspension issues that I found during the 30 day return period and they could not fix, fast enough anyway.
Customer service is great, and the return policy is best, but you have to be careful like at any used car lot.
I have a third one, a 2015 Z51 coming in the next few days.
I hope this one will work out, otherwise I will shelf my C7 endeavor. I am sticking with Carmax because of customer service, return policy, and their MaxCare warranty. Don't buy anything from them without the warranty.

 

I agree with the suggestion of trying another one. As with any car, not all of them are equal, especially ones with a history of accidents.

 

Sounds to me like you are complaining about the throttle response not being consistent with the driver inputs...... if that is the case, a Soler throttle controller will help you, it is adjustable for how quickly the throttle reacts to the driver's inputs

 

a Soler throttle controller is a must. I also changed my throttle body (also by Soler) as well and there is no hesitation at all! Instantaneous response! was a world of difference in my case anyways. Good luck

 

I really bad alignment will cause a floaty feel.

As mentioned a throttle controller will give you 100% linear throttle input.

 

Hopefully on the street you weren't driving the car that hard but keep in mind Traction Control and Active Handling will affect the car's behavior, including the power delivery. Your description reminds me of the first time I drove my C7 ('17 GS, M7) on track and found the power delivery to be very inconsistent - it was due to the driving mode I was in (this was shortly after I purchased the car, before I knew much about how to configure the modes).

 

The car may have had some modifications too. If it has a throttle controller and/or a custom throttle body, it may cause inconsistent pedal reactions. Usually you add them for the opposite effect, but I'm saying there could be poorly done modifications that you didn't notice - both for the throttle and for the suspension. My car is M7, with Z51 and Solar TB/TC and it's very predictable, very reliable and the handling is excellent.

Something is up with the car you were driving.

 

Couple things....
- The GS does not come with a track alignment, not even close. Having said that, who knows what it's set to so many years (and a couple accidents?) after it was produced. They're also very sensitive to rear caster. The C7 is one of the few cars with adjustable rear caster and most shops don't and frankly can't adjust it. I'll wager 9 out of 10 shops don't even know it's adjustable.
- Based on your description, it's an FE6 equipped car and not the FE7 (aka Z07) variant. FE6 cars do float and have a lot of roll. Still quite capable but not "track car stable". Switching to "Track" mode will help stiffen the shocks, change steering feel, etc but it's not a cure-all. If the factory Z07 parts are still available, it's an easy upgrade. Do note that the Z06 Z07 parts are different than the GS Z07 parts.
- Throttle mapping can be crutched with one of the throttle controllers or you can adjust it inside the tune using something like HP Tuners. As someone else mentioned, if you were driving even moderately aggressive in something like "Tour" mode, the nannies are much more intrusive and that affects throttle
- The car needs more tire in front to address push. I like 305s

All the above aside, in general I find it to be a great track day car with the exception of the transmission ratios. If you trace the lineage of the TR6070 transmission back to its roots such as the TR6060 in the C6 Z51 & GS cars or even the C5 Z06 T56, you'll find that the 1st, 2nd, and 3rd gear ratios are really for autocross. In fact the C6 Z51 was advertised as an autocross car. Because of the short ratios, you have a large rpm drop when you shift from 3rd to 4th which slows acceleration. Of course having said that, the car exits corners with authority with the shorter gears.

 

I was not doing anything egregious on the street. It was rush hour to boot. I don't need the vette to go fast or do anything stupid on a public road. The way I tested it is the same as I typically do any car I am unfamiliar with. I have no clue where/when/how the rear wants to break loose and I am not going to find out on the street. I will do a WOT pull and a hard brake to make sure nothing funny is happening and then the rest is using blue tooth and making sure every button and switch work. Mostly if my wife, who was with me (another reason not to be stupid) can work the infotainment we're good. I switched between driving modes and did not feel a particular change. I even took traction off, atleast partially off and still no dice on throttle input improvement. The best way I could explain it was that it felt very non linear, for maybe 25% of the pedal throw it was very clearly part throttle and was perfectly suitable for daily driving. Then around 30% of the pedal throw it felt like I had just went WOT and there was no more throttle modulation for a lot of the pedal throw.

I will look into the soler TB, thought having to buy something to fix a factory behavior is not an exciting proposition...

I thought the rear was very composed, actually it had so much grip I was not willing to push it and find out where it ran out because it would have required something extreme for the street. I also agree with the wheel/tire setup and was looking at going with a square 18" setup. I will also look into the z07 parts. Just from my initial research I think the GS might be oversprung for not having much aero. I'd also be willing to bet there is too much rebound for my liking as well. Deleting the MRC shouldn't be hard right? Just the proper resistor?

 

Wow that review in the OP is not anything what I've experienced with my C7 Grand Sport M7. Mine is totally planted (both of them..read on). Not wallowy at all. I've actually bought two new ones at MM at got to go to Spring Mountain owner school twice. The car is beast on the track, totally enjoyable (but I got to beat theirs, lol). I would try different one if I were you. I went from a C5 Z06 to the C7 Grand Sport and the difference in performance was night and day. And the C5 Z was no slouch. Yeah maybe the gears are long but in the turns is where she shines.

 

Fellow track user of GT350 there! I had quite a setup with JRI 2-way, full SPL, 305 square on 11 wheels, buckets and harnesses.
Now I own c7 gs mt7, non z07. I'm prepping my car for track duties now, but in the city at least front is brilliant; insane grip and stability. No substitute for double wishbones.
Certain "floatiness" of the suspension in Tour mode is there, not much in Sport/Track though. But if you want proper feeling I'd say get rid of leafs and go with coilovers.
Regarding the throttle - I noticed this as well; however, it may also be that the engine is throwing all the torque starting from 2k rpm. Need to visit the track to be able to understand if it's really a problem.
As others mentiones, z51 is base stingray spec; you need GS which is all goodies included already.
In my car rear is stepping out easily, but easy to get it back. E-diff is something I need to understand!

 

Yeah, glorified resistors. I'd buy spare connectors and add the resistors or just by the "sims" so that the factory plugs stay clean should you ever go back.

Regarding springs and aero....GM had to walk a tight-rope. They needed to account for basic "Stage 1" cars....plastic front splitter, small winglets in the back....and the "Stage 2" cars that still had the FE6 underpinnings. Mine is a Z07 setup but it can't keep up with the wing and splitter. There are some tracks where I have to intentionally slow/not go as fast as the horsepower would allow because the aero and elevation changes bottom out the car. Coil-overs are likely in my future.

It's like anything else with these cars.....Where do you draw the line? Stock is very capable but then you add one little thing....and then two....and then three....next thing you know it's gutted and caged on coilovers with a fire suppression system, fuel cell, electrical cutoff, and cool-suit!

 

It is hard to say what is the cause of the front-end handling that concerns you. The most obvious cause may be the differences between a setup M3 and a stock GS or a stock GS that has had its handling fangs pulled because a previous owner had a street alignment to get better tire wear. The wide Michelin PSS ZP tires are not really poor handling tires like early run flats were. They only have a stiffened sidewall on the inside of the tire with a non-run flat sidewall on the outside of the tire. GM test driver Jim Mero set lap records at various tracks using those tires. The cars did not come from the factory with a track alignment. The factory alignment settings for camber are about half of what the owner's manual track alignment settings for camber are so are nowhere near a track alignment.

Accidents could also be a factor in the handling feel but the C7 isn't as subject to those kinds of issues as a BMW or other unibody car would be since the C7 is a body-on-frame car where impact damage doesn't usually translate to other parts of the superstructure. M7 C7 Z had a heavy impact with the Turn 10 wall at VIR and after replacing a couple of bolt-on body panels, patching some cracks in panels that weren't damaged enough to replace and replacing the bolt-on right rear suspension components it is fine. They will take a licking and keep on ticking.

Since I have a Z06 my throttle response is different than the LT1 engine in the GS. Some of your throttle response problem may be due to the huge torque differences between a 97 M3 and almost any Corvette engine. They have a lot of low-end torque (even at 1000 rpm) and it comes on strong with small throttle movements.

As you can see the LT1 has over 300 lb ft of torque at 1000 rpm while the LT4 has about 450 lb ft of torque at 1000 rpm. Both have low-end torque levels that are greater than a lot of engines have for max torque at rpms ranging from 3500 to 4600 rpm with the LT4 being exceeded by only two or three other stock engines worldwide.

As you know even with an M3 poor throttle control can ruin a day at the track and the Corvette engines require even more of a feather touch to avoid purchasing part of a wall. They will do what you tell them to do almost instantly even though you didn't think you were telling them to do that.

Bill

 

Indeed, every track car I have run I have put on coilovers and valve them how I want (I have tools and a shock dyno in my garage). I prefer not to have tons of aero when it is a dual purpose car.

Interesting, I have driven cars with lots of low end torque. Mainly they have been all FI engines and not N/A. Still this was a very clear ON/OFF feeling, it very well could have been that the nanny's were on. Seems like I'm right in assuming it was partly me and very maybe the car's history being a bit of an unknown it will remain a ?? until i try another. Unfortunately there are no other M7's near me. I have the 8l90e in my ctsV and I for sure do not want it in a vette if I am going to get one.