Eric_Oz_S2

OK:

Sways - 30mm hollow front (with brace), 19mm 3 way adjustable rear set to middle with aluminium+delrin inner mounts
Spring - 350 F, 250R with stock S2 tbars reindexed (1 spline on inside)
Wheels - 17x7F, 17x9R (twists)
Tyres - Falken RT615 225/45F, 255/40R, run 36 hot all round (29-30 cold)
Shocks - Koni Sport front (with ARHK) set 1/2 turn from full rebound setting, Koni Series 30 coilovers rear, set at 50% rebound setting
All other bushings stock.
Camber F -2.7, R-1.5
Toe zero front and rear

Eric_Oz_S2

No - LSD - I do get a fair bit of inside wheel spin in corners, and I was thinking this could be contributing to the problem. A GT 40% is on the cards.

gt37vgt

with an open diff the first change i would make is go to the softest hole on that rear bar if not softer bar again. i have one here ..
944 challenge cars run no rear sway bar .
are you saying the rear end is unstable loaded or unloaded ??
I would generally be suspicious of the what rear toe you have ....under brakes and accelerate
as the rear end on these cars changes toe and camber quite a bit with travel ..

Eric_Oz_S2

I can get both lift off oversteer and power oversteer. On faster corners I can balance it on the throttle, on slower and compound or reverse curves it can get a little twitchy, especially under braking. But I have got it fish tailing exiting tight curves on (gentle) throttle.

Eric_Oz_S2

But the KW is more re-biased than what I am running?

gt37vgt

as these rear ends move the wheels around too much as they travel and yours misbehaves both ways i would say it wants more rear spring and valving ..
and just a reminder as the looks like its been forgotten that KW's are konis ...

333pg333

I think this 'KWs are Konis' needs to be quantified. They're certainly superior to the basic Konis and even some of the mid range. Perhaps they start to compare to the upper range Konis. I know that people have said that they're Koni inners, but I'd like to know the real story as a matter of curiosity.

Eric, the only time I've had similar characteristics as you describe is when I had my Mo30 sway bar when I'd move it off the softest setting. It would make the car rotate in similar fashion. First thing I'd do is move it back to the softest setting. I bet this has a pronounced effect. In fact I'm sure this will cure your present affliction as your setup shouldn't be too oversteer dominant.
I've changed to the Tarrett sway bars front and rear and strangely I've had both on soft, medium and hard and the car doesn't react nearly as much as the 30mm off full soft? Not sure why this is btw. Having the Tarretts on full hard front and rear makes the car feel REALLY flat and fast....but it hasn't necessarily corresponded to faster lap times. So what 'feels' fast and what 'is' fast can often be very different.

Also as Adam has touched on, this rotation could be as a result of some front to rear movement. So when you come into these slow corners you are probably under heavy braking and your front pitches forward lifting weight off the rear which responds by loss of adhesion. Pretty much like the 911 syndrome. It can happen on our cars too as much as we're led to believe that we have perfect balance. You could possibly need brake proportioning to the rear to also alleviate this effect? What sort of brakes and pads do you run?

Do you know what the stock T bars are, as in mm? You need to figure out what actual rates you're running, as in 'effective'. As you can see even in this thread alone there are people suggesting quite differing rates. Springs are pretty cheap and there is a lot of tuneability in decent suspension so don't worry too much. Whatever package you decide to buy will have plenty of room to move so to speak.

Oh, and if you're tracking pretty regularly you really should look to an LSD. Check with Sean / JET951, they might still have one in stock.

Eric_Oz_S2

Thanks for the suggestions.

Not sure what pads they are actually - haven't needed to change them since I got the car. They would be somewhat track orientated though - as the PO also tracked the car.

Stock bars are 24mm = 137lb/in. So total rear effective rate = approx 277 and is still less than 0.9 x front effective rate.

I was thinking about dropping the rear springs back to 225 or maybe 200 - as you say very cheap.

I'm a bit wary about running the rear sway on softest - I had this with the stock springs and it had terrible understeer on the track. That front 30mm bar is very stiff. There seemed to be a huge difference between the mid and soft setting.

I'm also going to put some toe in back into the rear, as it really can get nervous under hard breaking. I presume the braking is adding some toe out. It's interesting the alignment spec for the S2 allows 0 +/- 5' of rear toe for 89 models (so some toe out is OK) and 10 +/- 10 for 90+ models.

What toe are you running in the back?

333pg333

Just try the swaybar back a notch. It can't go from wanting to spin to massive understeer with half an inch. Understeer is safer anyway and you'd be surprised what times you get. Do you have the capability of changing it at the track? If you had big understeer with it on soft, and then changed the suspension plus moved your rear bar up a notch you need to see what it's like on full soft. I bet it will be better and won't have massive understeer. I know it's difficult at times, but it's good to only change in small increments. So you added some rear spring and you changed your sway bar setting. I'm betting on your sway bar.

I haven't checked my rear toe for sometime but I think it's neutral at the moment. There is a school of thought that you can toe it in a smidge as under braking it will naturally toe out. Also if you find that after switching your rear sway back to soft and it's understeering and hurting your turn in, you can run a couple of mm or 1/16 toe out on the front.

Rich Sandor

Not entirely true. Since KW broke away from Koni, KW has been designing and getting their own parts made. Some very early KW setups have Koni part#'s.

JET951

this your main problem. when you exit a corner hard with an open diff the wheel with the least resistance will start to spin, at this point the car is still controllable but very slow. Then the car will want to switch sides(fishtail) and this is when you are loosing control of the car, the weight will be transfered form one side to another and so will the power of the engine. This is very hard to control.
now no matter what direction you take whether it be keep your foot planted on the throttle or back off the likelyhood of tankslapping is very high. at this point you are just a passenger.

with a proper motorsport LSD when you exit corner and get wheelspin both the inside and outside wheels try and turn at the same speed, essentially locking the rear end. this will make the car much more controllable, it is also much faster seeing that power is being applied evenly to both wheels not just the one with least resistance.

the LSD will also make the entry into the corner much more stable by locking up under deaccelleration, this keeps the back end stable, particularly while trail braking into a corner.

My next step would to be to install a proper LSD, i wouldnt worry too much about changing your suspension setup at the moment.

Eric_Oz_S2

I think you are right about the open diff causing problems. An LSD is definitely on the cards.

I adjusted the rear toe today it was 6' in, now 15' in (total). I have heard the 911 guys often run 25' toe in rear. Also slackened off the rear sway to softest setting. Feels a little less "wandery" on broken surfaces.

The other problem I think I have is the right front seems to (just) lock up first, which may be adding to the instability issue. Not sure what is going on here as the brakes are freshly bled, perhaps some contamination? Rotors and pads have plenty left in them.

333pg333

So your S2 doesn't have ABS Eric? What year model is it? Sean will know but perhaps it was still an option when your car was brought into Oz? I agree with Sean that a decent LSD will also work wonders.

ehall

Okay...just need to add one thing...


One cannot "DEaccelerate". One can accelerate or decelerate. That which is in between is stasis....just saying....

thought we needed a bit of "English Tech" for those of us colonists who only marginally speak "The Queens".

Eric_Oz_S2

It is an '89. ABS was standard from the '90 model and an option in '89.