tmak26b

Today marked my first day on the Supercar Runflats on the track since last year. Let's just say they were almost scary compare to the R888 (which aren't exactly hot) that I ran on. Other than the lack of grip and response, one of the huge problem I had this past weekend was how nervous the car felt under braking. It seems like under any sort of trail brake, the back-end would step jump out. I am leaning toward a tire problem as the car didn't do that as much on the R888. What do you guys think?

AU N EGL

all C6s have Torque Management, that can not be turned off. A good programmer could set the tables so high that it never comes on.

AH & TC are never fully turned OFF even in the OFF position for C6s as well. So any really slip or the rear end would still experience TC.

So throttle steering and trail braking a C6 is not easy to do. a programmer needs to change all the TC, AH, and TQM tables.

Now that said if you get use to having the rear wheels firmly planted with minimal to no slip, the car is still very quick around corner. Just different then the C5s

tmak26b

? I have never felt any traction control or active handling kicking in the corners. And I dont run with the stupid comp mode or any of the BS.

I agree about throttle steer and trail brake, car is more point and shoot.

vette6aut0x

I have never felt any of the systems come on when it is enabled. And yes you can trail break and throtle steer with ease.

tmak26b

You must be really good, it wasnt so bad on the race tires. On the run flats, it was nearly impossible, especially after heavy braking zones.

varkwso

Having just ridden in the car and seeing this thread I was wondering - was it tuned out of your car? Cause you would have sure triggered it.

Also remember the video from Rd Atl last month from Jarreds car where your rear end was wiggling at T7 I believe - I attributed it to tires....

varkwso

He is....

kermooni

I am certainly not that good ...

But with an 06 A6 Z51 in Comp mode with R6's, DBA rotors, XP10s and XP8s, I never had any interferance from the AH except for one occasion when I had to seriously brake behind an M5 (applying way too much break) in turn 14 of RA. It let me brake hard and turn at the same time.

For the most part, I was practicing trail braking on the second day without any issues. But I do not believe I was driving any more than 75%.

In May at Brainard (stock brakes, with PS2s), I experimented in turn 3 by taking it in 2nd gear, that was exciting ... Thank God for AH

tmak26b

I just dont see how torque management can kick in when you are trail braking since you are not on the gas. I still believe it is a combination of tires and suspension design that is causing it. I am learning to drive with it, but it seems like the high speed to low speed corners are very tough with the car relatively stock. Someone had mentioned the lack of rear down force is a problem too, but not sure how true that is. Keep in mind this is a bone stock car, so experiences might be different in others.

I don't use traction control or active handling, doesn't want it or care for it. The only drivers aid I like is the ABS, but on the Corvette I am still a little iffy on it as my 350z had a nicer ABS system (not saying it stops better, it just felt better)

vette6aut0x

I dont think so. We found out why the rear was wiggling. Apparently using the LG coilovers as we found out from the man himself ( brother Tom has a hot line to Lou) we are going to have to lower the car at least 1.5 in. Lou said the car is to high for the rebound. We lowered it at Babers yesterday about .75 in. and it helped dramatically.

varkwso

Tom and "hot" in the same sentence - that almost never happens

I sure did not see any issues with wiggle for you guys at Barbers.

sperkins

How is it possible to throttle steer with TC left on?

Bill Dearborn

It is easy. Throttle steer doesn't mean you are spinning the rear tires. I was throttle steering for the early part of the day today in the rain. I had full TC on due to the constantly changing conditions and the slippery nature of the 6 year old SC tires I am using in place of R tires.

Throttle steering is the judicious use of the throttle pedal to change the yaw of the car. You can do it by leaving off the throttle or adding throttle or a combination of the two.

Bill

ajderzie

One obvious possibility is that runflats tend to bump steer because of the blocks inside the tire are very stiff. It's symptomatic of the tire. This was discussed here for years on the original Goodyear F1s. Go back to posts from 2003, 2004 and you will see a lot of conversation on the topic.

Maybe you are talking about oversteering where the back end slides out and not "bump steer" where the back end sort of skip shifts over.
If we're talking about oversteer and you don't trail brake as much, does the car understeer? If not, then maybe you are braking too hard into the corner.

tmak26b

I don't buy into the torque management thing, the car is not using power when you are trail braking anyway.

sleeper02Z06

Listen to what you are saying. Of course the car will feel less planted, more likely to step out, more nervous. This is not an indication of a problem, it is an indication of overdriving the available grip. When you put less grip on the car, driving style has to change. Brake pressure, turn in rate, mid corner speed, throttle application, everything changes just a bit. It's no different than when a tire goes away throughout the course of a session, you drive to the grip level. Your car and tires don't have problems.

Joe

sleeper02Z06

[QUOTE=tmak26b;1567110136
I agree about throttle steer and trail brake, car is more point and shoot.[/QUOTE]

No car is point and shoot, certainly not a C5 or C6. Any car driven with momentum will be faster than if it is driven with a point and shoot style.

Joe

sleeper02Z06

None of this matters in this particular situation. Stock C6's can be rotated, balanced with the brakes etc. without any PCM programming. I've been able to drift C6's as easily as my Camaro!

Joe

sleeper02Z06

Here is another way to look at it, and a particlar reason I HATE the improper term "trail braking". Instead of saying trail brake, tell yourself you are "braking to balance" because that is the purpose of carrying braking beyond the turn in point. It is not easy and when people have problems doing it, they blame tires or car setup. In reality it is the driver. I cannot begin to tell you what you may or may not have been doing wrong or even what the car was doing since iI was not in the car with you, but i can assure you if the car was nervous and unbalanced it was likely driver induced, especially in light of the fact that you say the car was great with R888's.

Joe

sleeper02Z06

Your last statement is most likely correct. There are simply too many excuses such as runflats being too stiff and causing bumpsteer being used to mask driver error. Is the suspension and tire setup on stock C6's perfect, of course not, anything can be improved. I'd be willing to bet that drivers need to improve themselves alot more than the suspesion needs to be improved though.

Joe