mtnspeed

After being a mild poster and lurking continuously, this is just too good to not post. Spent the last 2 days taking the 968 through its paces at Texas World Speedway. For those of you who race or track your 968, you know what I am talking about. The fun meter was fully pegged. After feeling completely humbled after my first couple of runs, I was managing to clock respectable laps time by the end of the weekend. Much smoother, better braking, setting the suspension, etc. Having multiple family members who track and race heavily, I believe I am 100% hooked. However, I do FULLY realize thinking you are a good driver and then taking it to the track are two very different things. I have raced mtn bikes, dirt bikes, and done some dirt driving=limited help on the track. The instruction I received this weekend simply exponentially increased the learning curve.

So, for the race and track crowd here, I have a few questions. First the details.

94' 968 6S, M030, LSD, 17" Cup II's bone stock (Unless Trevor did something to it I haven't figure out yet , lowered about 1".

First question: After getting slightly respectable I started really noticing a couple of items that were killing my performance compared to the other drivers around me.

1. Understeer...this got to be really bad with the car plowing heavily, especially in long sweepers with the throttle on and modulating to keep from drifting off the track. After adjusting the koni's to full stiff, and upping my front tire pressure a couple of times it did get better, but still diving and plowing a fair amount. Enough so that individuals commented "your line and approach are strong but the car seems to plow." Even my instructor agreed. I simply just didn't have the set up and quickly found the limits of it.

So, here are my first few thoughts that might help me out on this, and I would love some input from a few experts
1. My front tires are hosed, and I probably shouldn't have run with them to begin with. I will be dropping on 235.40.17 Hankook Ventus V12 Evo's on tomorrow, replacing the old Michelin Pilot Sports (they were 2003's, should have changed them prior...know better next time, please no flaming)
2. A mild camber adjustment. Just enough to help on the track without destroying the streetability of the car. My buddy's has dropped a new suspension on his E46 M3 and turned the camber. I couldn't even come close to holding his line. I would find my self plowing so hard if I tried and would have to let off. Seems this would help a bit
3. Lower it a tad more if there is anything left?
4. Adjust the sway bars, but this could be counterproductive.
5. New springs, as the currents are stock M030 and almost 20 yrs old.

It seems with relatively mild changes, I could carry a more neutral turn in and actually get a bit of throttle oversteer to modulate it if I needed. Simply more control. Stiffening the shock rates and more air did a bit of that and it was a vast improvement. Thoughts? Stack rank of the above. I am a novice, but want to learn more, so any thoughts would be helpful.

Oddjob

Tires, tires, tires. Very hard to determine a car's setup deficiencies on poor tires. Also, what size tires front/rear?

Moderate or compromise track alignment will help tire wear and some w/ turn-in. Will want some neg camber front/rear. What is the current front toe setting?

Whats the car's mileage? The concern of age/mileage is the shocks being worn out, not springs.

Adding more tire pressure to the front and increasing the front strut rebound will generally increase understeer. Was the worst understeer primarily at turn-in, or track-out, or both?

968 w/ factory M030 suspension and brakes? So the car has the barrel helper springs on the rear shocks, and it has the 19mm 3-way adjustable rear sway bar. What hole is the rear swaybar set at? Any idea how the rear shock rebound is set, soft or stiff?

pontifex4

How wide were your front tires? How wide are your rears? Going to 225s in the front from 205s with 255 rears (unchanged) substantially erased this trait for me in an M030 car set just above full-soft.

Notes: tire pressure changes are generally an attempt to keep wear and heat even in the tire. Take the pressures as soon as you come to a stop in the pits and try to keep them under 40 for street tires. A couple of lines of chalk across each tire in the morning will tell you a lot about how your tires are making contact with the track, too.

Also, generally speaking, stiff front end: understeer, stiff rear: oversteer.

It sounds as though you're approaching this the right way, so I'm not at all surprised to hear that you had a great time!

pnbell

From the sounds of it, your driving skills are fine, and your car is becoming the limiting factor. This is not a surprise because All Cars come from the Factory programmed to Under steer (especially after the 930 Turbo killed all its owners with Oversteer!)

Basically what others said above is correct; If you can stiffen your Rear Sway bar/Rear Shocks, that will help. "Tires Tires Tires" as said: are really the most important upgrade(at this point); especially going with wider front tires!

If you're looking to address high speed understeer issues, installing a front splitter would help.

M758

I am not going to make that conclusion yet. Understeer in a long sweeper can be due to technique as well as car. Your car is probably not optimized, but technique can make a difference.

On my drive to work I have a freeway transition ramp. It is a long left turn I can take 60-80 mph and I am in the turn for 10 seconds at least. So long sweeping turn. Depending on how I turn in I can get the car to understeer through there or be neutal to a hint of oversteer. This applies to my street 944 Turbo S or my BMW E39. Both are stock, but my turbo has an more aggressive alignment.

Anyway if I turn in really gentle the car will tend to understeer all the way through. If however I get the car to rotate more on initial turn it will be very neutral to a very slight hint of oversteer. It is an issue of under-roating the car at turn in vs getting back end roated and ligthening up the rear a bit.

Point is have raced for nearly 10 years I can feel this easily and while it quite subtle is very consistant. It is quite likely that you can get rid of much of the understeer by getting more rotaton at turnin and getting the car to take a more rear biased set. This will put more weigh on nose and less on the rear so front grips better even when going full throttle.

Now beyond just this you also need to have the car working right. If you are on l tires from 2003 it could very well be that what you are felling is mostly old tires. Get fresh ones with no more than 20 mm wider in the rear. Too wide in the rear vs front will create understeer too. Camber on front should be -1 at minimum and -1 rear. These are aggressive steet settings, but not ideal track settings. For ideal track settings you are looking more like 3 degrees of negative camber front and 2 in the rear.

My race car runs -3.5 and -2.5 , but some of that tire dependant.

M030 gives adjustable shocks and sway bars so you can play with them too. Start with tires first however as if you stay on old rubber you can just be chasing set-up by working around a bad tire. Oh.. and don't mix tires. Get 4 tires of same type on all 4 corners and of the same age. Different brand front and rear will cause a change to the balance. Not sure what the change will be, but it will be different and make proper set-up near impossible.

StoogeMoe

Agreed...you can't really determine setup on worn out tires. The Hankook's are a great choice. Let us know how it goes after your next track day. I'm sure it won't be your last!

If you still have the understeer with the new tires, be ready to make changes at the track. Since it won't be practical to change springs, that leaves you with changing the sways for moderate balance adjustment and tire pressures for the final tweaking.

mtnspeed

A. Not sure on the sway bar, but will be checking that shortly. The rear rebound is leaning towards soft at this point.


A. Stellar time!

A. Hell, I want one of these even if its just for appearance. If memory serves me right, the highest speed I was at exited a long sweeper had to be about 85. Either skills or set up was holding it back, as there was a fair bit more to have.

mtnspeed

Willing to bet this is mostly old tires. That will be fixed very soon, and a mild camber will be added to straddle street and track time. You are probably right on the driver's skills. While I improved dramatically over my 8 run during the weekend, there is a lot more to learn. I become much more comfortable setting the car up comfortably for the turns by the end of the weekend, but when even your instructor is questioning why your car is plowing so hard, you start to believe it's not just you.

As of next week, I will have a new set of RE-11's on the front and a full review (tweak) of the suspension. That ought to make a BIG difference. I have decided to stay on my stock Cup II's (7.5 and 9.5 x 17's).

mtnspeed

I will report back, unless anyone else has some additional feedback.

ritzblitz

RE-11s are a good choice... are you getting them for the rear though too? You better.

white924s

Tires make a big difference - I did my first few track days on ultra high performance all-seasons, then switched to Bridgestone RE050A summer tires and the difference was pretty surprising - the car gripped better and the feedback was more precise.

333pg333

Remember that most cars are setup for understeer and these are no different. The whole suspension could be looked at including all the bushings / bearings. Old tired rubber bushings will drastically reduce the ability to maintain geometry under various loadings. Clearly your tyres need attention but the closer size you have front to rear will also help reduce push understeer. As these cars are very close to 50/50 balance, they also respond to similar/same front to rear wheel/tyre size. Street tyres also won't help but so long as you replace them all together it should retain the same balance.

The stock M030, while being well thought of 20+ years ago, is now considered pretty soft. Seen too many stock cars pitch and roll about like a boat on a rough day. By lowering it you actually risk getting into your bump stops which will increase understeer, not reduce. So be carefull of that.

Van

If you were full throttle mid-corner, you probably entered the corner too slow, went to full power, transferred the weight to the rear, and got understeer.

teamking

I'm with Van, and want to hear more about how you were using the throttle.

The first time I went to the track, I thought I'd cure any understeer and get the car to rotate by mashing the throttle (in an S2000, in third gear!). Didn't work!

Later, when I learned how to drive the S2000 in autocross, I would have the car rotate by lifting (or trailing) off the throttle (aka trailing throttle oversteer). Following on Van's point, trailing off the throttle transfers weight to the front, giving it more grip, and away from the rear, giving it less grip, and now the car is oversteering.

You can do the Jeremy Clarkson flaming tires bit in cars with sufficient power whether they're set up for understeer or not. But it's not fast and the car's not necessarily fast.

But, ANY car (FWD, RWD) set up properly (my opinion) will rotate when you get off the power-- you get on maintenance throttle (maybe 20%) to shift some weight to the back to get it neutral.

Hope that's helpful.

xsboost90

full stiff on the front shocks only should have made the understeer worse. Hankooks RE615k's are awsome and they like 40psi hot.