Just installed my front Hotchkis sway bar. Full stiff... what a difference in corners.

By the way hotchkis front weight 15.2 lbs, vs. 10.8 stock... that's 4.4 lbs more. damn! I'll have to change my sig data

Now, I'm not sure what to do with rear. Leave stock or put Hotchkis. My car is little oversteering now. I remember thread about "help to plant my tail". What was the collective conclusion?

 

The effect you feel is the rear has lost traction thus causing less understeer. Carter and Jim explained this to myself and demostrated it to me as well. When you turn you'r steering wheel to the inside (does not matter wich side) it effects the rear by lifting the same inside tire (thus loosing traction in coners add in weight transfer its not a huge issue). Our Z's have a really stiff unibody and this is why this takes place. Requires a little more finess when driving threw an autocross not to spin the car. I personally went to bsp to have the rear bar and more traction from the rear. But it does work. Carter & Jim could explain better how to make it work.

 

With such a large front bar, it's hard to believe that you aren't experiencing heavy understeer. By increasing the front roll stiffness, I would think it would unbalance the Z. I run Nismo sways with Eibachs and Koni 8241 shocks- there are times I wish I could dial in MORE rear bar (rather than less).

I'd highly recommend matching your front bar with a rear bar of your choosing.

 

My car is 116 pounds lighter. Mostly from rear.
If I drive in circle and increasing speed my rear starts to slide out. that's oversteer, right? Will stiffer bar in rear fix it?

 

I just installed hotchkis sways myself with the front set to medium and rear at soft. I felt I needed more front bar, so I went to full stiff up front and kept the rear at full soft. I experienced the same thing as you (slightly tail happy/unsettled rear). I just adjusted the rear to medium and it seemed to plant things a little better.
Generally speaking, more rear bar will increase oversteer, but as mentioned above on more extreme situations (ie stock rear and hotckis front) the process becomes counter-intuitive.
One way to balance the sways is to have someone follow you (preferrably on a road coarse with sticky tires) and let you know if you are lifting an inside tire. On my last car, I was told that my inside rear was lifting, so I softened up the rear. If you watch some of the racing on speedchanel, you will notice that the inside front tire lifts off under heavy cornering on many of the bimmers.

 

Here is an exerpt that captures some different aspects of oversteer.

(From "Drive to Win" by Carroll Smith, available at Amazon.com)

At every level of skill and experience, the most common complaint of the racing driver is; "It pushes like crazy on corner entry then snaps to oversteer the instant I get on the throttle. Only a driver of my experience, skill, and daring could have brought this thing back to the pits in one piece. Fix it!"

We shall assume a certain level of objectivity on the part of all concerned - that the driver is not abusing the car by, for instance, entering the corners with the front tires on fire, that the car is properly aligned and corner weighted, etc, and that the crew is willing to listen. In that case, nine times out of ten in this day and age (the mid Nineties), entry understeer followed by throttle connected snap to exit oversteer is one of two things: a "fall over" problem or loose anti roll bars.

What usually happens is that the car is set up with too little front suspension roll stiffness relative to the rear. When the driver turns the steering wheel, it feels as if the car turns in instantly, but then the front "washes out" leaving the driver to deal with a lot of "Phase Two" understeer. When he jumps on the throttle the relatively strong rear roll stiffness causes oversteer.

What has actually happened in this case is that the car didn't really turn in - the initial lateral load transfer in response to the steering input caused it to "fall over" onto the (relatively) unsupported outside front wheel and it felt like it turned in sharply. This did bad things to both load transfers and tire cambers so the understeer reported for duty. When the driver applied the power, the rearward load transfer straightened the front up, the front tires bit while the relatively strong roll stiffness slid the car into power on oversteer.

This can be a very confusing situation for all concerned. The problem is liable to be more pronounced in slower corners. The road to salvation leads through the realization that the problem can exist and a thorough and detailed debriefing to an increase in front roll stiffness. Whether the solution lies in more spring or more bar is a subject for experimentation during testing - and the results should be noted in the ever growing "if then" book.

 

Vlad simple put a bar on the back, or soften the front to its lowest setting. Its lowest setting may be softer than nissan but probably not if it weight is more as you stated.
By the way the next time you siting still in you driveway have someone turn the steering wheel from lock to lock and you will see the rear lift and compress. Mine with stillen on the front traveled almost a full inch with no rear bar. This is how setting the front bar to full stiff works on a Z with stock rear bar.

 

All that suspension work is like magic to me... amazing

 

The softest setting on the hotchkis bars is stiffer than stock. My car handles great with medium up fron and medium in back. You can also try hard up front and medium in back.

 

I set it to Full front, medium back and it feels good, but I still can loose the rear pretty easily. I'll try medium/medium and full/full next.

Thanks for all the info

 

Try a softer rear if it keeps up. Also to how are you testing the effects? Try to find a empty parking lot that you can go in a large circle with gradual speed increase so the balance of the car will presents it self to you.

 

That's exactly how I test it.

 

I've got mine at full/meduim right now and it feels fairly balanced. I've got my first track event this weekend with this setup. I'll post my findings next week. Will be running my track wheels with 275's all around.

Perhaps you're loosing traction in the rear from too much camber? Have you tested with a pyrometer? I had this problem with my last car and it turned out that I was running about 20 degrees hotter on the inside f the tires in the rear. A camber adjustment brought me to a 10 degree variance and noticeably more traction.

 

Hmm... how can we change camber? I thought it's constant unless you got adjustable front arm for front adjustment

 

How do you have your sways set?

Full Front, Medium rear?

Right now mine are set at Medium front and back....

 

jwkirkland with eibach springs and stillen lower camber (no shocks yet their on the way) my car is set with softest on the front and full stiff on the rear. That will probably change with the konis.
vlad you are right. You would need to purchase front upper control arms and rear camber arms. It's the best way to increase turn in and grip in the coners.

 

thanks mpowers

I really need to go out and test different settings to find the right feel for me i guess.

 

I was changing rear brakes yesterday and noticed that my rear wheels are not evenly weared. The wear increases from outward edge to the inner egde. Same on both wheels. Like I have good piece of negative camber. Shouldn't it prevent oversteer?

Do you guys have the same wear on your tires? I don't remember such wear pattern on my stock tires, and all my suspension is stock, except swaybars. And my rear is almoust 100 lbs lighter now, so I'd expect cumber to decrease, not increase... puzzled.

 

got a pic?

 

as a matter of fact I did make a picture. but I don't have it on my pc yet.
It's just gradualy increasing wear from outside to inside. With thread depth decreasing from 5 or 7mm to 2mm or less.