My car seems to plow into corners on the road course. I have a base c5 with z06 springs and shocks. It's lowered on stock bolts and I run falken 615k's on z06 wheels. 255 up front and 275 rear. I also have c6 upgraded sway bars. I was thinking about getting a front splitter any ideas on a splitter or other means of helping understeer?

Thanks

 

Square tire setup. A 255/275 setup on real Z06 wheels will be stretched as well.

 

Are you getting this understeer at turn in or is it in the middle of the turn or when exiting the corner. Can't say for sure but it could be your driving and not the car. Have you had an instructor ride with you to see whether you need to modify your driving style?

C5's in stock configuration are inherently tail happy under trailing throttle conditions in a turn. Sometimes a quick lift off the throttle is just enough to make the car tighten into the turn so you can roll right back onto the throttle. If you haven't done much throttle steering practice it someplace where you have room to recover from a spin.

Bill

 

It should have minimal understeer. You should probably check out the front suspension and alignment

 

What are your alignment settings?

 

I've been fighting the same thing recently. First, my front tires are shot! Completely destroyed with unusual wear. I think its a combination of things. I think over this past year I've become a lot faster at the track and I've been pushing the car more to the point my front tire setup is insufficient. I run 315/30/18 rear and 275/40/17 NT01's. I think the fronts heat cycled out before the rears as the are a smaller tire, which was causing mid turn and exit understeer. Second, the front control arm bushings are pushing out of the control arms. Being an 03, I think it's time to possibly upgrade. Third, I run -1.7 camber up front and -1.0 in the rear which is a general camber setting most people start off with when running a performance tire. I think as I've become more comfortable with the car as I really feel molded to it especially with the addition of the Sparco seat. I think I've out grown the "beginner" settings and really need to step up my game. The car has always felt safe and understeered slightly which was just fine at the beginning...now I'm trying to breaek my old lap times and feel I can with out a problem....it's just the car doesn't want to cooperate.

More experienced driver's here all tell me to run a square setup or atleast a larger tire upfront. Depending on wheel size in the near future. I was contemplating 335/30/18 rear and 315/30/18 up front with much more camber. I've been recommended -2.5 front and -1.5 rear and adjust from there. You are running much smaller tires which is not a problem but I suggest possibly getting more aggressive with the alignment. It really changes the car.

 

Stronger rear sway bar, or less front sway bar. If all the other specs are correct.
REALLY old road racing rule,,,,,, stiffest end of car slides first.
Swaybar adjustment is a quick and dirty way to fine tune the balance of a race car. that is why race cars have cockpit adjustable sway bars that the driver can move in real time.

 

This^

I believe C6s are heavier on the front sway bar. Try a Hotchkis rear or a C5 Z51 front. Changing a rear sway bar is a 15 minute way to change your chassis from plowing to dangerous oversteer. So, play with bars, but don't over-do it.

 

The Hotchkiss rear for the C-6 is three way adjustable, not sure about the C-5 application.

 

Thank you everyone for all the help. I'm going with more rubber all around, some camber in my alignment and playing with sway bars. We will see what happens. More seat time always helps too!!

 

Don't forget tire pressures. Its another adjustment tool along with suspension components. You could drop 2 psi in front and increase 2 psi in rear and tune out some unedersteer.

 

Remember, suspension settings are all interactive, change one thing and ALL the others are affected. Lowering the front tire pressure will reduce the front overall spring rate and help with under steer, but the tire has a small window of pressure to operate in. Lowering the front pressure too much, can cause under steer, so you get my point.
1. Make and test one change at a time, record all other effects of that change. You may find that camber, toe or caster are effected by your first change. ( lower tire pressure might need more neg camber)
2 suspension tuning is done by one change at a time and looking at all the other values. this is why pro teams use data and engineers to analyze it.
3. What might work,,, tire pressure changes, tire temps, camber changes, caster changes, corner weight , side weight, fr /rear balance, sway bar rates,
4. What WILL work is understanding each change before you make another. By not tuning each area to its peak, you can find a balance that feels good, but the car is slow overall. OR understanding what you are doing, you can tune the car correctly, find the balance with all settings at their peak and have a Fast car.
5. It's your hobby, why not study the engineering and understand how to tune a cars suspension. Way more fun when you know what you are doing.

 

Excellent comments from Racer and exactly what its best to change the easy thing first. My car and driving style on OEM tires was neutral handling. I just replaced the tires with a different brand so will have to tune pressures first, striving for neutral again, then see what issues there are.