I seem to be the only one with an oversteer problem on a 350Z. I have 350 evo sways, front upper control arms and stock shocks/springs. My car has terrible (steady state) oversteer. I spoke with the good folks at 350 evo who suggested trying some toe-in in the rear, so I just had another alignment done yesterday and got .08 toe out in the rear and -1.6 degrees of camber. I previously had 0 toe all around.
Since I installed the control arms and sways at the same time, I figured the oversteer was due to my new found traction up front, but after a quick spin in the hills with stock camber up front and stock tires, it still was an unsteady mess.
Hopefully the alignment will take care of things. Has anyone else experienced this? Perhaps the car has too much bump steer?
What are people running for track alignments?

Here's a link for your viewing pleasure of what I am dealing with. The oversteer is fun for a few laps then it gets old as you struggle to build up any kind of corner speed. It never looks as dramatic on film, but in real life it felt like the tail was out there forever..

http://www.we-todd-did-racing.com/we...ZmQzMXk1NDE%3D

 

Is that video of the 0 camber?

What do you have your sway bars set at?

 

I've pretty much tried every combination but right now, I'm at med/soft. BJ recommended going back to med/med to keep the rear suspension travel at a minimum. I'll have to see this weekend how it reacts at thunderhill.

 

Maybe it's just me, but are you accelerating before the apex?

Maybe what's happening is that you're turning in with a little bit of trailing throttle?

 

listen to your tape and you'll hear that you are on the gas before the apex which will create your oversteer.

 

try some toe out in the front and some toe in in the back. and maybe a drivers training course.

 

guys,

he is an HPDE instructor. i think he has enough experience to know when the car is oversteering or not.

i don't have an answer for his problem, but i thought a little bit of defense for daveh was appropriate.

sean

 

Dave:

I have the same setup except Koni's all around. I also have Khumo V700 275's all around and do not see this. How about you come try my car again and see if there is a difference. We can take it for a longer drive.

I ran Laguna and do not see that kind of response. It was very balanced. I am the limit to the speed the car can go and I like it that way.

I did here you tire screaming maybe it is a tire and suspension incompatability.

Ray

 

D*mn, that's some nasty oversteer! I can't do that even using 2nd gear! This is probably too simple of a solution, but have you checked the accuracy of your tire pressure gage?

 

I know I am asking the stock suspension to do more than it is designed to do. I have to get on the gas a little earlier to weight the rear to get a little more traction out of it. The screeching you hear in the video is all coming from the rear tires!

To further explain the oversteer that I am experiencing, if I go to an empty parking lot and do some friction circles and slowly build up speed, my rear end will loose traction before the front. I am talking about what happens only at 9/10ths, not something I normally experience unless on closed track. I am very critical when it comes to cars, maybe most people wouldn't notice what I'm talking about. I have tuned many cars and think I have a good grasp of handling dynamics. In fact, my last car (a lexus with 72 less hp) was turning similar lap times to my stock z because I spent a good year setting her up. Anyone in clubZ can attest to that. Anyways, I'm not getting into how bad a driver I am (I know I have room for improvement )

Ray thanks for the offer, but it's too hard/dangerous to reach the limit on the street. We'll have to catch up some time on the track.

I'm hopeful that my toe-in in the rear will calm things down. Usually minute changes in toe can make a big difference.
I was really trying to spark an alignment discussion to see what people have tried and how different changes have affected handling. It is quite expensive to have an alignment done every time I want to make a change. Maybe we can help each other out so we're not all re-inventing the wheel. (no pun intended)

 

Dave I am doing a track day March 8. That is a Tuesday. You could come up and ride with me to see the difference. What do you have planned for April. I am going to be out of the country the week of my clubs April (18-23)event so I am looking for an April track day. Maybe we can find a track day that fits.

 

Hello Dave, I see you are still having the issue with the oversteer.
I don't know if this will help you or not but here is my set up for autocross. In the front I am running 3.2 degrees of negative camber and positive .02 on the toe (toe out). In the rear we are running 2.3 degrees of negative camber and .011 degrees negative on the toe (toe in). We find this works great on the autocross for keeping the rear from stepping out. In a static circle the whole car slides (maybe 50ft). I need a large pad to increase the speed but the effect should be relatively the same. From what we have read and done with other cars for autocross this is almost a generic for a rwd car. Toe out in the front for better turn in and stability and negative toe in the rear for straight line stability.
Another thing to check on our Z's is the wheel base lenght. We have set up four 350z to date for autocross, all of which have lowering springs. Three had eibach and one had hotchkis. All three with the eibachs were a pain in the *** to even get the toe and camber in the rear to come to a happy medium. In doing these we discovered that the wheel base on one side would be shorter than the other as much as 3/8 of on inch. It took some time to have an equal wheel base on both sides and have a proper alignment. The hotchis did not have this problem, but their springs only lower to something like a little over an 1/2 an inch to less than 3/4". While the eibachs did the full 1". We also learned we would have to ignore the caster that the computer showed for the front. One last thought we use a Hunter DSP400 alignment machine.

 

Dave, sorry i didn't know you where a HPDE instructor. I still think your problem is toe in the back

"just had another alignment done yesterday and got .08 toe out in the rear and -1.6 degrees of camber. I previously had 0 toe all around."

A 1/4 in toe in in the back would help alot. toe out in the back is just going to make it worse.

 

oops meant to say rear toe-in. My new alignment has toe-in in the rear, not toe-out. I previously had 0 toe on all 4 corners.

 

Damage to the rear suspension pick-up points? Soft bushings? Something else that may be generating positive camber (or less negative camber) on the outside-rear tire?

To me, at least on that video, it looks like you're squaring off the corner entry, knowing that you're going to have to "catch" the rear end.

 

1.6 degrees negative camber in the rear seems kind of mild, considering the stock alignment specs allow up to -2.0. You also run 17" wheels, which may allow a little bit more lateral flex with the taller sidewall. Did you converge on that setting based on temperature readings across the tread width after doing friction circles?

 

That is a crazy amount of oversteer. It looks like in the first corner you may be getting initial oversteer on entry -- possibly when you lift throttle -- but that should be cancelled by throttle application. In the scond turn you appear to be at a steady steering lock, and when you apply power, the rear end takes off. In both cases, the car seems to be over-reacting to power application.

You didn't say how much neg you were running in the front -- or what tires you have (I assume track-worthy rubber?). If there isn't some gross problem with the suspension, as alluded to by PDX-racer, you probably have too much front neg and rear bar.

I would try disconnecting the rear bar and see what happens.

I had my Stillen bars set at medium/stiff (front/rear) and the Tanabe springs, and when I added the A-arms the car became neutral with very slight oversteer under full throttle in 60 mph corners -- on street tires.

 

I wouldn't rule out wheel flex either.

light-strong-cheap -- pick any two.

(BTW, I have some experience dealing with wheel flex causing the "front camber" to go to about 15-20 deg positive)

 

Holy cow! That really looks like a lot of fun.

 

PDX_Racer wrote: "(BTW, I have some experience dealing with wheel flex causing the "front camber" to go to about 15-20 deg positive)"

Ah, more testimony from the bleeding edge of FWD "technology." Soon, my son, all those trials will be a distant memory.