Ok this might be more for the guys who autoX. My 01 Z24 have oversteer. I truly do not mind it. I would rather have oversteer and understeer. I do not really plan to autoX (other than trying it out). I might do some road course stuff, but nothing to serious either. Other than being lowered, and form front sway bar bushings, and strut bar that is it. My question is if I went with rear sway bar, tie bar, and anything else will my car go from oversteer to understeer? Is there a happy medium? I really do not want understeer. The over steer I haveI can deal with and control. Tha ks for any comments, tips etc..
FU Tuning
I want to know how you have oversteer, what's been done to cause this. I've never heard of an oversteering J-body.
14.330 @ 96.37mph
Stiffening up the back will make oversteer worse, although I'd like to know how you have oversteer to begin with as well.
Quote:
Oversteer is a phenomenon that can occur in an automobile which is attempting to turn. The car is said to oversteer when the rear wheels do not track behind the front wheels but instead slide out toward the outside of the turn.
This is what my car does. It does not do it every turn, but if I push it super hard in a corner it does. I have the same tires all the way around with good life on them. I guess I got lucky. I like oversteer, so I just wanted to know because I do not want understeer.
FU Tuning
What tires and tire pressures are you running? A 2lb difference between front and rear will make the difference between over and understeer depending on tire tread and compound.
James Cahill wrote:What tires and tire pressures are you running? A 2lb difference between front and rear will make the difference between over and understeer depending on tire tread and compound.
I'm running Cooper Zeon's ZPT's. Tire pressure is usually around 40psi all the way around. Where I do agree tire pressure can make a difference in handling, I do not think that is my issue. Of course could be wrong.
I also just thought about the fact that I have Koni red's. The fronts are on soft while the rears are on full hard. This set-up is more for the drag strip, but maybe that plays into why.
Edited 2 time(s). Last edited Sunday, June 01, 2008 8:33 PM
FU Tuning
That, and the fact it occurs when you pus\h "super hard" into a corner. My guess is you're on the brakes at the same time, completely lightening the load on the rear tires, causing it to rotate around sooner than the front.
Your excessive tire pressure is causing this too, as you're only riding on the center of the tread instead of a fuller contact patch that would be provided with lower pressures.
14.330 @ 96.37mph
Yea the high tire pressure isn't helping, but having soft setting on the front struts and hard on the rear will definately point more toward oversteer. If you add a rear sway bar, you may consider adjusting the koni's as the rear will become what i like to call " twitchy" - the front will plow and track whle the rear will skip around at cornering limits.
I think the way you have your Shocks adjusted plays a huge part. During hard cornering your front end has more traction due to a softer setting. where as your rear, being at full hard , has less traction then the front causing it to break loose. I'm not sure what the effects of adding a rear sway bar would be but i would say if you do decide to get the rear bar you should play around with your tire pressures and dampening levels to get the type of handling that you want. If you like the way your car handles and feels why do you want to install a rear sway bar and tie bar? If you mostly drag race and do not do AutoX I would leave it the way it is. Adding more bars means your adding more weight and in drag racing ,as i'm sure you know, adding weight is not a good thing lol.
Well I hope this helps
John, if you want to get rid of the over steer, try bringing the rear tires down about 1-2 psi lower than the front. off the top of my head, your tire pressure are probably not too far off from where they need to be with 215/45R17's to maintain the load of the vehicle.
generally something in the range of 37 front and 35 rear - 40 front and 38 rear should help get the car a little more balanced. the car (all cars really) are designed to understeer since it is much easier to control an understeer condition than an oversteer. bring the car back to a more neutral setting should help you out in not getting oversteer. personally, i like my car to handle on the verge of oversteer, but not to cross it.
1997 Cavalier Z24 - 15.647 @ 88.02 MPH
I do not feel my tire pressure is too high (I mean for daily driving). That is why they are set that way.
Quote:
That, and the fact it occurs when you pus\h "super hard" into a corner. My guess is you're on the brakes at the same time, completely lightening the load on the rear tires, causing it to rotate around sooner than the front.
That would be incorrect. This is not using any brake at all in the corners when it happens.
I'm not saying I want to add rear sway bars, but something I thought about. The info you guys have given me is very helpful. To the fact that I will probably leave my set-up as is for now. The Koni's are adjusted as they are for drag, and I do not mind the oversteer. I also do not want to take a chance of adding rear sway bar and making it worse than it is.
Again thanks for everyones feedback.
FU Tuning
Quiklilcav wrote:I would definitely drop those pressures down a little bit. That tire is most likely designed for about 35 PSI. If you do as Whitegoose suggests, and go 37/35, you might get a little closer to neutral with your cornering, and your car should ride just a little better, as well as not wearing your components as hard (ball joints, bushings, etc). Our cars are light enough that 40 PSI on a tire of that size is overkill. Remember that they typically gain 3-5 PSI when they heat up from driving. I always go a couple of PSI higher in the front just to compensate for the extra weight of the engine that's not in the rear. Keeps the contact patch more even.
Whatever you chose to do, at least you've got most of your questions answered and can make an educated decision. 
My tires are designed for 45psi. That is why I keep them at 40 cold knowing they will gain psi with heat. I did not buy my tires for performance, but for price and how long they will last. Saying that they have performed GREAT!!!! I do realise if I was going to actually AutoX, or road course driving tire pressure would need to be adjusted (no different than going to the drag strip). I also have a set of sticky tires (use them for the drag strip but could also use them in autoX). My question was more for the driving I currently do which is on my 17's wityh 40 psi of air. Since I like the way the car handles and seeing my main purpose for my car I will probably leave things alone.
Thanks to everyone your info was very helpful.
FU Tuning
No, your tires were not designed for 45psi.
The higher the pressure, the higher the load-carrying capacity. 45psi is when that tire will carry it's heaviest load, safely.
I usually run mine around 33-35 and it's set up very nicely, just about neutral (keeping in mind rather extensive suspension mods).
14.330 @ 96.37mph
im retarded... could someone please explain over steer and under steer...
Riddle me this... riddle me that...
BlownBlackZ wrote:No, your tires were not designed for 45psi.
The higher the pressure, the higher the load-carrying capacity. 45psi is when that tire will carry it's heaviest load, safely.
I usually run mine around 33-35 and it's set up very nicely, just about neutral (keeping in mind rather extensive suspension mods).
Let me say the place I got them from recommends them run at 40 psi.
FU Tuning
z yaaaa (the riddler) wrote:im retarded... could someone please explain over steer and under steer...
Oversteer- picture fishtailing in a RWD car. When the rear of the car "steers" beyond the corner, regardless of steering input.
Understeer- plowing. When the car fails to corner, and the front end actually slides sideways towards the outside of the corner.
ok... rear has addco sway, tie bar, strut bar and a trunk floor brace, with yellows/sportlines... yellows are full soft all the way around.
fronts- stock sway and an rk sport subframe brace and strut bar.
225/45/17's at 40psi
which way SHOULD i be going? under or over?
Riddle me this... riddle me that...
I would have;too say more oversteer than under with ur suspension mods imo
Nuetral (neither).
The J platform has so much understeer built in (a combo of the caster, control arms, and trailing beam rear), that you've only cancelled it out (or you're still understeering). Now you can start playing with tire pressures, camber angles, and tire compounds to make the car rotate. Even different tire sizes (a 205 is much easier to push sideways than a 225) will allow play.
A car with an ideal setup will be neutral (leaning towards understeer) during normal driving and cornering (even racing), and be able to exhibit oversteer only when needed or wanted (ie- quick steering input, quick brake, etc, etc, all depending on driving style).
^^^ ive noticed that the steering is slow and sloppy, i wish we could do something about that.
the difference between a stock and and a stock mazda 6 is like night and day, if i could have the tight steering like one of those cars i would freaking LOVE IT.
Riddle me this... riddle me that...
z yaaaa (the riddler) wrote:^^^ ive noticed that the steering is slow and sloppy, i wish we could do something about that.
the difference between a stock and and a stock mazda 6 is like night and day, if i could have the tight steering like one of those cars i would freaking LOVE IT.
Never noticed sloppy steering on my J's.
FU Tuning
John dude 40 psi is TOOOOO high. Your car is 10 PSI over-inflated from what the factory recommends(30psi) and 8PSI from the norm (32psi). Your over-inflation is causing the center bulge a little causing your thread-width to be as wide a motorbike's tire. Our car's 60/40 weight distribution makes it really light for 40psi use, unless you have a Sub box, amps in the trunk and two 250lbs fat chicks on your back seat.
Now I have neutral steering, I have 25mm F/R bars BUT I have the GM welded bar too, which makes the rear suspension very rigid. On our cars to get neutral, you have to go a little bigger (sway bar) in the rear, then the front. You can also use shocks to dial this, but that should be done as a second choice or a supplement.
I am also running 34PSI Front/ 32PSI Rear, just so my rear contact patch is wide and have enough PSI for the engine weight and front plow.
The ONLY things I can see good with your PSI is that your fuel economy will go up as the with less width for aerodynamics with low rolling resistance and you car is ready for the autobahn (high speed run) with full capacity weight in the cabin and trunk.
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-----The orginal Mr.Goodwrench on the JBO since 11/99-----
Mr.Goodwrench-G.T. wrote:John dude 40 psi is TOOOOO high. Your car is 10 PSI over-inflated from what the factory recommends(30psi) and 8PSI from the norm (32psi). Your over-inflation is causing the center bulge a little causing your thread-width to be as wide a motorbike's tire. Our car's 60/40 weight distribution makes it really light for 40psi use, unless you have a Sub box, amps in the trunk and two 250lbs fat chicks on your back seat.
Now I have neutral steering, I have 25mm F/R bars BUT I have the GM welded bar too, which makes the rear suspension very rigid. On our cars to get neutral, you have to go a little bigger (sway bar) in the rear, then the front. You can also use shocks to dial this, but that should be done as a second choice or a supplement.
I am also running 34PSI Front/ 32PSI Rear, just so my rear contact patch is wide and have enough PSI for the engine weight and front plow.
The ONLY things I can see good with your PSI is that your fuel economy will go up as the with less width for aerodynamics with low rolling resistance and you car is ready for the autobahn (high speed run) with full capacity weight in the cabin and trunk.
Sorry I do not air my tire based on the factory recommended settings. I go based off the recommended setting from the tire maker. Also I did not, nor do I buy my tires for my 17's for performance. I want then to last. I did get lucky that they wear well, and perform well. I have spoken to 2 other J owners (yesterday) who experience the same thing I am (oversteer), not bad oversteer, but they can push on them to get them..
Again everyone was very helpful with information and helped me make my decision.
FU Tuning
