I just put new swaybars on my F45 suspension 02 and while I can really feel a difference in the handling I find the back end losing grip in high speed cornering where I never had that problem before. I took a curved ramp off of one highway merging to another that I can usually feel confident on at 75 mph. I really thought I was going to lose it last night on the same ramp. the back end seemed to jump or bounce out several times on the curve. It felt like if I had downshifted or braked to hard it would have come around on me. What gives with that? It was very disconcerting(scary as hell) and while I love the faster, flatter cornering with the front end this rear thing is bugging me. Anyone else have this or have any suggestions? Thanks FLYZLOW

 

Did you double check all your connections? Maybe some bolts got loose? Good luck.

PS what freeway do you normally travel, just want to make sure to keep away from you. Just joking....

 

I know, I know, it's the loose nut behind the wheel!! The ramp is westbound loop 101 in Phx where it exits to go south on I-17. The speed limit is 65 so I'm not too terribly out of line and insane!

 

The standard sway bars have their stiffness adjusted for lower skill drivers, that is to create understeer in extreme conditions. Understeer is when the front tires will become looser before the rears. Narrower front tires also contribute to this effect. The ZO6 bars are not only stiffer, but the ratio of stiffness front to rear is changed to create a more neutral characteristic, slightly approaching an oversteer condition. It is much easier to go really fast this way because you can control the rear end with the throttle.

American car makers have employed understeer in family cars for many decades because the powers that be have a belief that when in a high speed situation, the driver is better served by going straight on into whatever they are trying to steer away from. If you have largely driven American cars and become acustomed to underteer, suddenly have a more neutral to slight oversteer balance will be disconcerting.

As for my C5, I not only have the same ZO6 bars, I have wider front tires. The car is now very 'tossable' in slower to medium speed corners, and even with the A4, allows a reasonable measure of throttle steering....swinging the rear end around by application of the gas pedal.

If you are running the factory funflat tires [Extended Mobility ] your car will never handle correctly. The ultra stiff sidewalls of this type of tire inhibit proper contact of the main tread against the road surface.

Hope this holps......

 

I do not know for your sake,but have your tire pressure checked regularly and treadlife left.Likey you have done this ,but I thought I would try offer one other angle to look at.Goodluck

 

If you are running the factory funflat tires [Extended Mobility ] your car will never handle correctly. The ultra stiff sidewalls of this type of tire inhibit proper contact of the main tread against the road surface.

As per the quote above this is the sole cause of the problem you are experiencing. The Z06 bars were not designed to be use with the run craps ...

 

I would definite rather have a car loose than tight. Tough to throttle steer a tight car. With the Z06 bars/Bilsteins I can let the back come around a little and stay in it. With the stock bars and a tight car - now that's scary.

Learn to use it and it a hell of a lot of fun with the traction control off.

 

Close, but from what I've read they designed the car to understeer because they assume that an inexperienced driver will be driving the car (which is true 99.9% of the time) when it goes too fast into a turn. If the car starts to lose control the inexperienced driver will take their foot off the gas and apply the brake, which is exactly what you need to do to stop an understeering car from crashing. If they set it up to oversteer, or be neutral, then when the inexperienced driver goes into a turn too fast and starts to lose it (oversteer) and takes their foot off the gas and onto the brake, they will make the problem worse and cause the car to spin! Given the choices, it seems to me to be a wise decision to set a dealer sold car up for understeer from the factory for sale to the general public.

If your front bar is tight you can consider puting the softer rear F45 bar back on the car to reduce the oversteer characteristics you're experiencing...check your air pressures too.

And I'd never recommend running on the street without the computer on...IMHO.

BTW, did you lower it when you put the bars on and did you check your allignment? Lowering the rear will toe-out the wheels and create oversteer on the turns. FWIW

 

I woke up this morning to lots of great input,Thanks! Let me provide some more facts. The back end isn't sliding out it feels like its hopping out just enough to want to make a driver want to brake or downshift. I didn't do that. I didn't lift at all I just steered though the corner. I'm used to racing a mid engine car that will come around on you in a heartbeat if you screw up. I also drive a C4 that will do donuts till the cows come home so I am familiar with routine oversteer.The tires are all at 30lbs. and are indeed the factory runflats. So far it sounds like a combination of the tire design and the rear bar. If it was just drifting out with a little squealing I would not be concerned but it seemed to "pop' out then grip then "pop" out again all through the turn. maybe four times through a sweeping, slightly banked turn. My speed was'nt high enough for me to expect any oversteer at all. My experience said don't lift, don't brake , don't down shift. Maybe I need one of those giant Ricer Wings to give me more downforce!! Anyway, it wasn't the secure feeling I am used to in this car on a "baby" turn like this one. Any more thoughts before I try putting the stock bar back on the rear or is that a No- No? Thanks again for the help.

 

It almost sounds like you are experiencing a bit more bump steer with the Z06 bars and the runcraps that you were experiencing before.

If you have a buddy with another C5 without runcraps, see if he will let you borrow his wheels and tires. You will notice a night and day difference!

 

with Ted


another thing you may wish to look at is the AGE of the tires, not the tread depth. The tires may look great with lots of tread depth, but the rubber ages. Tires that are more then two years old have lost most of their grip for performance use, no matter what the tread looks like.

tread is for channeling water out and away from the tire. Look at racing tires very very little if any tread. Except for rain tires.

The age of the tire and rubber have more to do then how much tread depth is remaining.

Good Luck

 

I have read other posts that have said Z06 sways on standard suspension will unbalance the handeling because they were designed to be compatible with Z06 springs. Check other posts. I believe Hotchkis are more neutral bars on standard springs

 

With the stiffer bars you are feeling undulations and or bumps more. Some of those bumps or undulations will upset the car and make you lose traction. That's where Bilstiens or 04 Z06 shocks will help.

Steve

 

Check all your anti-roll bar connections again (just to be sure) and then,
LOSE THE RUNCRAPS!

 

My .02 :

Is it loose, or does it 'hop' around? I found with my Z51 suspension, and runcraps it gets a little dicey going around bumpy turns. I have an off-ramp near my house that I used to get a little squirely on. There was a bump about halfway around the turn. At 45 MPH I would hit that bump and almost always get a little squirely. After letting a few pounds out, I now can hit that turn a little faster and the car feels much more predictable. I run 28 lbs cold in the rear. Also, when I was running 30lbs, the center of the tire wore quicker. My new set of tires seem to be wearing much more evenly.

 

Good luck, because I plan on adding z06 sway bars real soon to my C5.

 

I have Z06 swaybars and have no problems like you describe, but I don't have runflats. One thing you need to watchout for is the grooved pavement. Before I got rid of the runflats I would experience bump steer, similar to what you describe. Maybe the Z06 bars are just aggravating the bump steer.

Good luck.

 

I've been eyeing the z06 sway bars too but I still have the run flats. I think I may just wait until I am ready to replace them. I already suffer from the bump steer and don't like it. I don't want to spend money on the sway bars and make it worse.

 

I drove the ramp today several times and now believe that it is partly due to expansion joints on that section. I never had a problem there before but it is obvious now with the new sways that the car does react badly(HOP, BUMP STEER, SQUIRRELY,WHATEVER) when it hits a bump in a turn. I have 9200 miles on my runflats and lots of tread left so I will wear them out before replacing them. I'l also try 28 cold and see what happens. Thanks to everyone who replied! FLYZLOW

 

You too are probably right on target! Thanks for the reply. FLYZLOW