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911st 911st is offline
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Join Date: Jan 2004
Location: Sacramento
Posts: 7,269
I believe a good starting point for a sport suspension might be:

22/28 for and early 911,
22/29 for SC/Carrera's,
22/30's for 930's.

I am still wondering about using coil over's only on the rear without reinforcements. One of our owners here found cracking at where the stock cross member meets up with the sides on a stock suspension 3.0 Turbo. His shop said this was typical.

Some have eluded that some or all of the 3.3 Turbos have been reinforced and ok without reinforcement but that the non-turbos do need to be reinforced.

I do not know what to believe.

I would think that larger torsion bars even to the point of running smaller sway bars would be a good choice for 930's. Moving spring rate from the sways to the springs could keep about the same total wheel rate in a corner but increase the squat and pitching under acceleration and braking.

Just a note, a stock 26mm rear torsion bar is equal to about 175# in wheel spring rate. A 33mm rear torsion bar is equal to about 425# per inch or about a 500# or so coil over because of the difference in where the shock attaches to the rear arm.

To complicate things, on a stock 930 I suspect the torsion bars are about 60% of the wheel spring rate and the sways are most of the rest. Thus, if you double your torsion bar spring rate, you are not doubling your effective wheel rate.
Old 10-30-2009, 09:21 AM
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