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fredmeister fredmeister is offline
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Join Date: Oct 2002
Location: Baltimore, MD, USA
Posts: 2,235
Originally Posted by Yargk View Post
I have 22/29 mm torsion bars. Feels great on the street, but the rear is too soft for the track. Specifically, 22/29 is not balanced compared to a stock 930.

Stock 930 18.8 / 26

so 22 / 29 is 87% stiffer in the front and 55% stiffer in the rear

I am going to switch to 31s in the rear (keeping the 22s in the front) or go for 23/33

IMHO, I think the following are good setups:

21/29 56% stiffer front 55% stiffer rear
22/31 87% stiffer front 102% stiffer rear
23/33 124% stiffer front 160% stiffer rear

These rates are for 930s, for which people tend to want stiffer rears, however the logic might apply to narrow body turbo 911s too.
I agree the balance is critical or you will induce more understeer or oversteer than you would like.
I have 22/31 hollow bars in my street/track 930 and the ride is well controlled on track but not really too harsh on the street either. Could it be more hardcore for track yeah, but I do well enough by driving to track days with it while other faster cars get trailered to events. The ride on the street is not much more stiff than the stock bars were. The squat and dive are still present slighlty now, but not to the point I am rubbing tires. And my car is lowered to slightly less than euro ride height but not as low as some track only cars.
One added benefit I noticed was I wasnt detroying cv joint boots after track events because the suspension wasn't going thru such extreme ranges of travel as with the stock springs.

1979 930 Turbo....3.4L, 7.5to1 comp, SC cams, B&B intercooler, Snow Perf water/meth injection, Rarlyl8 headers, Garret GTX turbo, 36mm ported intakes, Innovate Auxbox/LM-1, custom Manually Adjustable wastegate housing (0.8-1.1bar),--running 0.7bar max
---"When you're racing it's life! Anything else either before or after, is just waiting"
Old 06-04-2013, 09:22 AM
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