We had yesterday our first tests for this season (other Mika [Häkkinen] was testing GT3 cup car and needles to say, he was a bit faster), anyway, we still had lots of problems with the handling of the car.
Car is oversteering and it is really hard to speed up from the corners because of massive wheelspins.
Car had bendt trailing arms last season and i thought that problems were solved by changing them. Because of the trailing arms we could not had toe in for the rearwheels.
Here is some specs of the car:
22mm weltmaister torsion bars (i also have 19mm and 20,5mm bars)
20mm swaybar (at the softest)
Koni red's with race modification allaround
adjustable coilover rear springs
no rear swaybar
215-45-17 s-03 front tires and 235-45-17 s-03 rear tires
all the bearings and balljoints are new

engine is allmost stock 3.2 with 270hp and 325Nm

I need to take the car back to shop to re-adjust the wheel allignmets. We picked the car from the shop on our way to track and there was about 1/2 inch toe in in front and also too much in rear. We tried to adjust the toe in but it was done without proper tools at the track so it is what it is.

So, what would you guys say? I really need help because there is no other track 914 currently racing in finland so no-one has the right info.
I would need advice for toe-in/out, camper, castor ficures and rear/front suspension set up

Thanks

-Mika-

I would start with a limited slip. If you don't have one with that much power, your going to have wheelspin out of low speed turns.

what spring values do you have in the rear? If the car is set up super stiff it will make the wheelspin even worse with no LSD.

dr

Your front anti-sway bar is not large enough. At the very least, set it at a much stiffer setting.
This will reduce the oversteer and also help the wheelspin a little.
Without a limited slip careful application of the throttle will be required regardless of the suspension settings.
I would set the front and rear toe both between 0 and 1/16" toe in initially. Slight toe out up front is ok and might help the car turn in better.

Thanks guys

I will check the rear spring ratio but it i dont think it is super stiff.

"Your front anti-sway bar is not large enough. At the very least, set it at a much stiffer setting."

-what size shoud i get? i'll try to set it stiffer.

"Without a limited slip careful application of the throttle will be required regardless of the suspension settings."

-I have tried to be careful, maybe i should try to set the engine management system to reduce the rpm rising speed. I would prefer to solve this problem without that kind of tricks.

"I would set the front and rear toe both between 0 and 1/16" toe in initially. Slight toe out up front is ok and might help the car turn in better."

-car turns great and there is no understeer in any condition. I will ask tireshop to adjust toe to 1/16".

Do any of you happen to have limited slip diff for sale? I would prefer "used" so i wouldnt have to pay big taxes when it arrives to finland?

HumbleMika

yupp, this is part of your problem ...

the bar is a bit too small, plus, if the rear is loose, you need to tighten the front. put the bar tighter and try again.

this won't help you much with the power-oversteer (spinning wheels) tho, you really should get a limited slip ...

can you run wider wheels and tires in your class or are you already maxed out?

and here's another one which is completely for free:
LATE APEX that'll give you a more straight line out of the turn ...

Andy

PS.: how about some pictures of your track-day???

Ok i will stiffen the front bar and i'll try with softer rear springs (just converted the kg's to lbs and it seems that my rear springs are 350lbs ).
i'll try to attach couple of pictures.


I dont know if that picture thing worked but you can go to www.bogeyracing.com and then to "Tapahtumat" and then "testipaivia2004" and finally "Ahvenisto 26.5.2004"
There is also better pictures of the GT3 which Mika Häkkinen is going to race this weekend in Ahvenisto race track. There were also other F1 driver testing in wednesday, Mika Salo who used to drive Sauber and Ferrari F1 race cars.

Mika

350 is way too much rear spring in combination with 22mm t-bars and a 20mm swaybar upfront
Either get bigger stuff in front (23mm t-bars and 22mm way - even then the 350's might be too much)
Or get something softer in the rear

JMHO

cheers,

Jeroen
PS I like your car!

I recommend stiffening the front with a larger sway bar, and leaving the rear at 350#. I have 400# rear springs, 23mm front sway bar and 22mm torsion bars. My car is very neutral with almost no body roll in corners.

Ok, should i chose 200 or 250lbs rear springs with the current front combination? I will pick new rear springs in monday.
I think i will also ask my friend to make me a 23mm sway bar and 22mm torsion bars. Then i think i would have enough combinations to any track in Finland.

Thanks a lot for everyone.

I still have one week to prepare my car for the first race

-Mika-

250

I also have a set of 23mm torsion bars if your interested.
I had them on my car for a month and it was way to stiff for the street.
I agree with everyone.
I'm running a street car with a stock euro 3.2
The throttle induced oversteer was terrible.
I now have no oversteer and a little bit of understeer.
Much safer on the street.
I'm running in the front:
22mm weltmeister sway bar almost all the way in (hardest setting).
21mm torsion bars.
205-50-16 tires
In the rear:
140lb springs
stock rear sway bar.
245-45-16 tires.
I'm also running bilstein's all the way around.

I'm running the rear sway bar because I live in Laguna Niguel.
Its very hilly and we have some corners where when I'm in the corner going up a hill and in the corner I go over the hill.
The weight is suddenly lifted off the rear tires and the car spins out.
I was very lucky when this happened there was no other cars around.
The rear sway bar eliminates this problem and keeps the rear of the car on the ground. Problem solved!!!
Most people on the track don't use a rear sway bar because at high speeds it can make the car unpredictable.
Its also a preference issue...

Steve

Mika,

1.0mm toe in each side on the front. 1.5-2.0mm toe in each side on the rear. 2 - 3 deg caster.

ok. i will pick my new 250lbs rear springs today.
tomorrow i will go to allignment shop and help them to get it right.

still need to get my brakes fixed, there is a small leak in somewhere.

i will let you know how it worked.

-Mika-

One more thing, just to make sure.
When you say that i need 250 springs, is it 250lbs/inch?
That is the figure that i converted to kg:s.
So in kg:s my new springs are 40kg/cm which shoud be around 250lbs/inch.
am i right?

-Mika-

you are correct sir.

dr

Ok, first race weekend is finally done.
suspension was much better with the 250 springs and a new allignement.
Still need to make new droplink for front swaybar so i can adjust it harder.
Saldo of the weekend is 3 cv joints, 2 pinionaxle teeth and something else in gearbox. i did not opened the gearbox after the last race but there is crack in the end piece of the tranny and it does not work.
the only time when i did not used the tow truck to get back to pit was the first race which i managed to end up 4th.

do you guys have good ideas what is causing the cv failure? it is allways the left inner cv and allways in the same part of the track where i am speeding up and changing from 3th to 4th, it starts to speed up in 4th but soon after it breaks either gearbox or cv joint.

i will post pictures soon

-Mika-

Mika,

The symptoms you describe seem to have more to do with aerodynamics than your suspension specs. My WAG is that you have insufficient rear downforce compared to
the front of the car. Under braking at high speed corners, the rear end gets loosey,
out of the corner you got wheelspin. I think you gotta get the front & rear downforces
corrected.

Phil

tranny problem

1st race

and after the 2. race

Last time I saw a pinion shaft like you, Dave Ferguson was holding it up and grinning that grin of his... "Know what this means? It means that my car does make enough torque!!"

Try the billet intermediate plate, and a spraybar to get oil directly onto the ring and pinion mesh. There are other tricks you can do to a 901, but I don't know what they are. Or give up and install a 915 gearbox with the trick Wevo s--t to let it shift decently.

CV joint problem--might be that you're working it to the end of its axial travel and a bit beyond. I have heard of people re-locating the C-clip that holds the joint onto the axle shaft, and putting longer splines on the shaft to allow the inner race to slide a longer distance along the shaft. Two different racers have told me that it solved all of their CV joint problems.

I've also heard of people using VW Bus CV joints; they claim those are stronger. Renegade Hybrids makes (and they and we sell) a kit to use different CV joints that are supposedly stronger.

Caster: 6 degrees is stock. A lot of people I know say "max caster". It makes the steering effort higher at high speeds, but it gives the steering more self-centering action and IMHO a somewhat better on-center feel. I think 2-3 degrees is far too little.

Camber: Check the temperatures across the face of your tires. Try to get the temps fairly even across the face of the tire; then you'll have the camber pretty dialed-in for that track. Alternately, try to set the car up so that the tires wear as evenly as possible. (Promotes longer tire life, but may not produce the best lap times.)

--DD