After installing c6 z51 sway bars and poly bushings the rear of the car feels much "twitchier" when entering or exiting a corner. When pushing the car in corners the "active handling" comes on much sooner and I have to turn it off to be able to push the car in corners at all. Any one else have a similiar experiance with the c6 z51 sway bars on a c5? It only becomes a factor when the car is close to the limit, it still handles well but its a little scarier than before. Ive read that c6 zo6 bars will cause heavy oversteer on c5s but based on what I read about the z51 bars I thought I would be happy with them

 

What tires do you have on there? I forgot.

 

It's really a driver perspective thing and how you like the car to feel.

I have C5Z06 bars and I find it tends to understeer every now and then if entering the corner too fast but tends to oversteer if I enter a tigher turn slower and use the gas exiting the corner - which makes sense. On merge ramps or more sweeping turns it can understeer while under power. Overall though, it understeers more than oversteers. It's a fine line though though and doesn't take much to change from one to the other.

The C6Z51 bars are 1mm bigger front and 1.8mm bigger rear so I'd have expected very similar handling. If you don't like it then maybe you'll have to try a C5Z06 bar on the rear to drop 1.8mm in the rear or something like a Pfadt C6 street bar to raise the front 3.9mm. Soften the rear or stiffen the front to move towards understeer.

You could also try something simple like put rubber bushing in the rear which will effectively soften the rear bar slightly.

One other thing - what shocks are you using? Base C5 shocks will tend to allow the rear to "hop" sideways on bumps in a corner which could be what you're feeling. C6Z or Bilstein shocks should help with this. I really couldn't tell you for sure with the C6Z shocks because my old shocks were so worn out any new shock would make a big difference.

Peter

 

There's another very good question. Everyone reports that runflats are crappy for handling. I've always run on Michelin PS2's because they came on the car so I've never experienced the runflats.

Peter

 

1 year old kumho spt fronts 245/40/18...305/30/19 new hankook ventus v12 (I will get new hankook fronts soon)

The car definatley has no understeer anymore. I really need to get the car on a track to test its limits. I am also running a slightly more aggresive alignment than stock. I am running c6 zo6 shocks.

I had ps2s on the rear b4 I wore them out and got the hankooks. Great tire....just really expensive.

 

A 245 with a 305 is really out of proportion. With the wheels you have 245 and 285 was the stock setup which personally I really didn't like. You need at least a 275 upfront and keep it within 30mm.

Also I am not to sure about running a 305 on a 19x10 inch rim that pushing it a tad. Also I am really unsure about the Hankook they may be the root of your problem with the oversteer. If they don't grip well and the Kumho's have more grip upfront that just may be the cause.

You can add a little more camber in the back to help with the oversteer issue or put a small diameter bar back there which could correct the issue.

 

start with a matching set of tires before you waste anymore time chasing a setup issue.

 

There might be your over steer problem. The one year old Kumhos have far more grip then the new hankooks, so the car turns in quicker or the rear is loose and swings around

never put two differnt types of tires on your car. Keep all four the same type and age if at all possible

When you get the new tires on have an alignment done as well

Good Luck

 

It has to be the sway bar because the 305 ps2s I had b4 worked great. The hankook is narrower than the ps2 and looks like a perfect fit on the 19/10. I need to get new fronts and go from there. Which tires are you going to run at BW?


I would hope the hankooks are grippier than the kumhos...I paid more $ for them







Thanks for all your input

 

All sway bars do it allow the tires to do their job by keeping the weight from swinging to the loaded side of the car. The car will definitely feel different because the car is spreading its weight across the tires differently, in more of an even fashion.

Make sure the bars are in correctly and you didn't miss anything, then look at the alignment and tires. The new sways can amplify an existing alignment issue. All that any suspension upgrade does is allow the tires to do their job, this is where all the feel is.

I would think the sways leveled the car a bit more in the corners and as a result took out a certain degree of under steer from the car. Now it feels like its over steering since you were so used to the old set up.

Hey, you could just slide the rear a bit !!

 

auto-x guys like the Hankooks more as they slide around corners better then Kumhos or Hoosier As

 

I'm pretty sure PS2's would have more grip than Hankooks. As for the current rubber, I don't know but others here are saying the Hankooks are the worst. At any rate, matching the rubber would likely help your situation.

for now, try lowering the rear pressure to about 28psi and raising the front pressure to about 34-36psi.

Peter