[stewhatch]

Finished my first Autocross of the season today. Adjustable Koni's set at full firm in front and medium (full firm then backed out 1.5 turns) @ the rear. Started with 40 psi at all four corners - using street radials (Dunlop SP8000 Sport new w/ approx. 600 miles) ... all new OEM suspension bushings and caster blocks + brand new M030 sway bars / bushings . The front end felt wonderful; wherever I pointed - it bit and went. The rear, however, didn't feel like it was able to keep up with the same level of grip as the front end. I dropped rear tire pressure in 2 lb increments between runs and improved 1-2 secs. on a 40 second course but I still experienced rear end drift when pushing hard thru almost 120 - 180 degree turns. How can I get the rear of the car to bite and track as well as the front? This is a street car with stock 16" rims. Also, what are my rim options if I want to invest in sticky tires? Am I limited in selection of cheap (used) wheels?

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[PorscheG96]

Does your 968 have the stock tire sizes of 205/55 front and 225/50 rear? Do you have limited slip? When was the rear losing grip...entering a corner, mid-corner, or exiting a corner?

You had the right idea by reducing tire pressures but you need to check tire pressures after each autocross run with an accurate gauge. 40psi starting pressure is OK but they will go too high in a hurry. Next time try 38/38 psi, then 38/36 for the next run, then maybe 36/34 or 33 and keep an eye on the sidewall to make sure you're not rubbing beyond the tread surface.

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[S_Cal968]

As you probably know there's a lot that affects an oversteer condition. I'm assuming you have the stock spring rates[?]. What setting are using on the rear s/bar? From what understand, a firm setting adds to oversteer. Try adjusting the rear s/bar to a softer setting, [mid or outer].

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[stewhatch]

<!--quoteo(post=72514:date=May 25 2009, 11:14 AM:name=PorscheG96)-->QUOTE (PorscheG96 @ May 25 2009, 11:14 AM) <{POST_SNAPBACK}><!--quotec-->Does your 968 have the stock tire sizes of 205/55 front and 225/50 rear? Do you have limited slip? When was the rear losing grip...entering a corner, mid-corner, or exiting a corner?

You had the right idea by reducing tire pressures but you need to check tire pressures after each autocross run with an accurate gauge. 40psi starting pressure is OK but they will go too high in a hurry. Next time try 38/38 psi, then 38/36 for the next run, then maybe 36/34 or 33 and keep an eye on the sidewall to make sure you're not rubbing beyond the tread surface.<!--QuoteEnd--><!--QuoteEEnd-->

I did happen to monitor tire pressures between runs and pressure did rise as temps increased. I adjusted accordingly.


<!--quoteo(post=72520:date=May 25 2009, 01:55 PM:name=S_Cal968)-->QUOTE (S_Cal968 @ May 25 2009, 01:55 PM) <{POST_SNAPBACK}><!--quotec-->As you probably know there's a lot that affects an oversteer condition. I'm assuming you have the stock spring rates[?]. What setting are using on the rear s/bar? From what understand, a firm setting adds to oversteer. Try adjusting the rear s/bar to a softer setting, [mid or outer].<!--QuoteEnd--><!--QuoteEEnd-->
I am running stock springs F & R - I wasn't aware that the M030 sway bar was adjustable; I didn't install it so I can only assume it is on a medium setting perhaps? Thanks to both of you for some valuable input - I appreciate the replies.

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