nile13

I had a chance to instruct at a Porsche NCR autocross on Saturday. One of my students had a 993 coupe with PSS9s. I drove the car on one of the runs and felt that it was understeering fairly severely, although it felt pretty decent otherwise. So, the question is - how would one set the PSS9s for more neutral handling on a 993?

Other things to consider - this car has Kumho Victoracers, 225 front and 275 rear (not ideal combo and definitely a contributor to understeer). When I drove the car, tire pressure was at 37 front and 34 rear, unbeknownst to me. I told the owner to set it to 42 front 37 rear, but did not have a chance to drive again after that.

So, any and all input on setup would be appreciated.

Jeff 993TT

Look on this page for "Chassis Tuning & Modifications"

http://www.rennsportsystems.com/1-e.html

For the track, I usually run my tire pressures about 33/36 hot. I have my pss-9's set up 3 in the front, 2 in the rear.

Sounds like his tire pressures were waaay to high, and are they switched? I usually have less pressure in my front tires than my rears.

You can also firm up the rear shocks to take out some understeer.. Or adjust the sway bars. What sway bars was he using?

chris walrod

My first thought was that the tire pressures were switched

Of coarse the 275's dont help matters much in terms of understeer.. Its too bad the PSS-9's dont have BOTH bump and rebound adjustment. Given enough time, one could dial in a set-up for that particular layout, that particular day..

Do you know what his alignment settings were? Maybe less front toe-in?

Where was it understeering, corner entry, exit, middle?

nile13

The pressures were definitely reversed, that was obvious from the first blush. I don't think that 42 is high for Victoracers on a heavier car, I used to run them at 36/38 on a 2500 lb MR2SC and about 30/28 on a 2250 lb Miata.
His sway bars are stock, as far as I know. PSS9s were set to soft front and half hard rear (not sure how many clicks, this is what I've gathered). He told me that it still understeered a bit after the pressure adjustment, but I have not had a chance to drive the car again.

nile13

Chris, it was understeering from the moment I would start rolling on the gas in the corner. The course was pretty funny - 4 slaloms, 3 pivots. And about a mile long. You can imagine the speeds (I ran out of second gear in an unfamiliar 993 on an unfamiliar course). The slaloms were huge - 10 cones and about 60 paces for one of them. The car did not seem to want to wiggle its tail through the tighter slalom, like I would like it to.

I'm not sure what the alignment is, but it is what it is. The only adjustment means available are PSS9s and tire pressures. I will have a chance to see that car again in two weeks and would like to set it up a bit better then.

I must say this. I have not pushed the car hard, obviously, and I am used to a CSP Miata on coilovers and 13" Hoosiers, but 993 behaved pretty good. Would be nice if understeer can be better controlled.