power oversteer issue
09-11-2012, 09:42 AM
#1
Pro
Thread Starter
power oversteer issue
I just added Koni sort shocks to my car. I had a chance to run at a non SCCA event so I raced on a set of WC true slicks (305, on 18x10.5 rims all around) I run Hoosier A6 normally (315x18 rear and 285x18 front on OEM c5Z rears (18x10.5) .
At this event the car was very loose under power. these non DOT slicks seemed to have more grip. but putting down power was an issue. another driver was running these same tires with about the same power output but was not as loose as I was. So I was thinking I must have the shocks set wrong.
the car is a 2002 C5 Z06
VBP sport leaf springs(775-875 front, 700-775 rear)
Strano 35mm front swaybar
oem Z06 rear sway
any Idea where the shocks should be set?
At this event the car was very loose under power. these non DOT slicks seemed to have more grip. but putting down power was an issue. another driver was running these same tires with about the same power output but was not as loose as I was. So I was thinking I must have the shocks set wrong.
the car is a 2002 C5 Z06
VBP sport leaf springs(775-875 front, 700-775 rear)
Strano 35mm front swaybar
oem Z06 rear sway
any Idea where the shocks should be set?
09-11-2012, 01:15 PM
#2
Melting Slicks
If you had the car balanced on a staggered setup, it's going to oversteer when you go to a square setup. You will need more front bar or less rear bar to get the balance right.
With the Koni sports on a stock C5Z the fronts should be a bit stiffer than the rears, but the settings should be close to the middle of the adjustment.
If you set the front rebound too high you will have oversteer (putting more weight on the rear tires) under power. If you are too soft in front rebound you will keep weight on the front tires and not be able to put down power. Since you only have rebound adjustment, you need to stiffen the front rebound some, the limit being that you get oversteer as you power out of the corner.
Since you changed three things at once (tire type, stagger and shocks) you are going to have to do some tuning to get it all working right.
With the Koni sports on a stock C5Z the fronts should be a bit stiffer than the rears, but the settings should be close to the middle of the adjustment.
If you set the front rebound too high you will have oversteer (putting more weight on the rear tires) under power. If you are too soft in front rebound you will keep weight on the front tires and not be able to put down power. Since you only have rebound adjustment, you need to stiffen the front rebound some, the limit being that you get oversteer as you power out of the corner.
Since you changed three things at once (tire type, stagger and shocks) you are going to have to do some tuning to get it all working right.
09-11-2012, 03:09 PM
#3
Melting Slicks
Also, loose under power isn't the same problem as putting down power. You've kind of said both things and they aren't the same problem.
Some people say they can't put power down when they mean the car steps out and they can't get into the power.
If you can't squeeze on the gas just past the apex, because the tail feels like it wants to step out, then as I said, you have too much front rebound.
But, you have to be careful, because if you don't shift some weight aft, you will break the rear tires loose, and that can make the back end step out and cause oversteer.
So, the question is, does the car feel "loose" in that the back end is trying to pass the front end when you squeeze in some power (and not enough power to break the back tires loose), or is it breaking loose when you put too much power and don't have enough weight shifting aft to plant the rear tires.
The fix is front rebound, but if it's loose on the squeeze you want less front rebound, if you aren't planting the back tires, you want more front rebound.
Some people say they can't put power down when they mean the car steps out and they can't get into the power.
If you can't squeeze on the gas just past the apex, because the tail feels like it wants to step out, then as I said, you have too much front rebound.
But, you have to be careful, because if you don't shift some weight aft, you will break the rear tires loose, and that can make the back end step out and cause oversteer.
So, the question is, does the car feel "loose" in that the back end is trying to pass the front end when you squeeze in some power (and not enough power to break the back tires loose), or is it breaking loose when you put too much power and don't have enough weight shifting aft to plant the rear tires.
The fix is front rebound, but if it's loose on the squeeze you want less front rebound, if you aren't planting the back tires, you want more front rebound.
09-11-2012, 03:41 PM
#4
Pro
Thread Starter
I really need to get back out on the Hoosiers, to get a true feeling.
On the Slicks it was both things. the slicks had massive wheel hop off the line. and also when getting back on the gas the car wanted to come around. They felt like they had way more grip in a turn that was a steady speed, but if you added a bit of gas as you exited and it was a wild ride. also the slicks felt real stable under braking
I was running the Pfadt sport shocks before, and this was the 1st event with the Koni's. They seem to be much stiffer and the ride comfort has dropped, like that matters.
On the Slicks it was both things. the slicks had massive wheel hop off the line. and also when getting back on the gas the car wanted to come around. They felt like they had way more grip in a turn that was a steady speed, but if you added a bit of gas as you exited and it was a wild ride. also the slicks felt real stable under braking
I was running the Pfadt sport shocks before, and this was the 1st event with the Koni's. They seem to be much stiffer and the ride comfort has dropped, like that matters.
09-11-2012, 04:40 PM
#5
Le Mans Master
what is the alignment settings?
We had some people in other RWD cars ( and some vettes ) that were loose on corner exit and they dialed in some more rear toe IN for the rear. Or maybe it's the opposite... when Sam help me set the car up he commented that since I didn't have the shocks yet that we wanted more toe-in out back.
Maybe you should take some Toe in, out of the rear?
As far as ride quality, are you setting the shocks back to normal ( full soft ) after the event? I've been told that the car feels allot better in street mode when you turn them back a bit.
This is all based on the research I've done before I buy my Konis this winiter. I've been asking alot of questions and getting feedback from other guys about them.
Hope that helps some. Like Solofast said, you made a bunch of wholesale changes at the same time, so you might have to try a few different combos before it sorts itseld out.
We had some people in other RWD cars ( and some vettes ) that were loose on corner exit and they dialed in some more rear toe IN for the rear. Or maybe it's the opposite... when Sam help me set the car up he commented that since I didn't have the shocks yet that we wanted more toe-in out back.
Maybe you should take some Toe in, out of the rear?
As far as ride quality, are you setting the shocks back to normal ( full soft ) after the event? I've been told that the car feels allot better in street mode when you turn them back a bit.
This is all based on the research I've done before I buy my Konis this winiter. I've been asking alot of questions and getting feedback from other guys about them.
Hope that helps some. Like Solofast said, you made a bunch of wholesale changes at the same time, so you might have to try a few different combos before it sorts itseld out.