taly911

Hi Adrian
Sorry for the late respond, I was busy tuning my MoTec , the front wheels are 225/40 9x18 rims, the rears are 265/35 10.5x18 rims, Bilstein HD shocks with H&R coils, 26mm front and 19mm rear stabilazers, Strut Brace.
Tal

joey bagadonuts

Perhaps this is splitting hairs but there is a big difference between karts and cars--namely, karts don't have springs or shocks. So when you change the pressure on kart tires, you're also changing spring rates and weight transfer which has a significant affect on the kart's oversteer/understeer tendancies. With cars, adjusting tire pressures will also affect those handling characteristics but to a far lesser degree.

With tires, you also need to consider that there is an optimal, target pressure--a level which provides the most grip. So it's difficult to generalize regarding pressures since raising or lowering psi's will have varying effects, e.g. if a tire starts above the target pressure and you lower it to the target pressure, grip increases; if you lower it even further, grip will decrease.

Does that make sense?

DanielB

Your car seem to be modified a lot and i guess it is lowered and pretty stiff in terms of a road car.

A very good and simple modification, though critical that it is done with high precision, is to add a good amount of negative camber. Look att 2 degrees in front and 1.2 on the rear as a medium setting. If you do plenty of trackdays go for front 3 and rear 2 degrees. If you never track your car use 1.5 front and 1 rear.

Maybe trivial, but never set positive camber as a fix for balance as it also will decrease the effective tyre contact area when cornering. On the opposite negative camber will increase contact area and the amount of lateral acceleration the car can generate.

Do it while having a full wheel alignment and corner weight done.

If you can adjust your swaybars stiffen the rear, alternatively loosen the front a bit. 26 mm in front with 19 rear is understeer biased, but it also depends on the lever length on the swaybars compared to OEM.

pzull

ABSOLUTELY! What I would do is to find the optimum pressure for the track by measuring the temperature of the tire threads (after several hard laps) in the middle and 2 edges such that they are as close as possible ie. no under or over inflation (but camber causes different temps between inner edge and outer edge of threads).

Once the optimum pressure is found, then I would make adjustments to my suspension to tune in a handling that I like. And I can do this very easily in the pit lane, just 10 secs per shock.

Adjusting tire pressure to change handling is something you do only if you have zero budget at the moment. It might change handling with extreme changes in pressure but ultimate grip and hence cornering speeds will be reduced. Not that I'm such an expert race car driver :P

DanielB

As you state this is a zero budget fix. However, you will always end up with uneven temperatures if you run zero camber.

pzull

oh nooo, never zero camber. zero camber means positive camber on turns. I'm running around 2 +-0.5 (can't rember now, exactly but remember shop mentioning a number with a 2 in it)

R6XTERRA

your rims are sick looking.....what are the specs and where did you get them?

taly911

They're 18" BBS magnesiume, the front's are 9" width and the rear's 10.5
Tal

Cuppie

Run more neg camber.

Mel