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Registered
Join Date: Oct 2005
Location: Capistrano Beach, Ca.
Posts: 7,235
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Ride height adjustment
Since most posts give ride heights measured from the ground to the top of the wheel well, does anyone know the approximate change in height for each degree of change in the rear torsion bar? Simply put: reindexing the rear torsion bar one degree will lower (or raise) the height by___?____inches (or fraction thereof).
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L.J. Recovering Porsche-holic Gave up trying to stay clean Stabilized on a Pelican I.V. drip |
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06-13-2007, 06:29 AM
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Join Date: Jan 2004
Location: Pittsford, NY
Posts: 3,701
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one variable you need to identify is the t-bar size. bigger bars at the same angle as the old bars will give you a taller ride height as the bars won't twist as much.
If you use the angle calculator (search Wil Ferch) and set the weight numbers and t-bar size you can get Euro ride height numbers and that will give you an idea of the height you are trying to find.
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Tony G 2000 Boxster S |
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06-13-2007, 06:35 AM
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Wash. State
Join Date: Jun 2006
Posts: 3,569
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Speaking of ride height adjustments, are better points of measurement not from the ground to various points on the chassis? Surely the body can be slightly out of whack, but isn't the chassis less likely to be so, assuming no damage to the underside/suspension parts?
I ask because that is how my shops go about these things. My car is such a better ride siince it was adjusted, aligned, and balanced. Although the fender heights are ever so slightly different, I wouldn't dare change things for fear (real) of upsetting the balance and feel of the car. Night and day from when I got it! I can't find any sign of an accident, but I'm pretty sure at least the left rear fender was reworked at some point, so I reckon twenty plus years of gravity and driving has simply worked its magic on the attitude of the body of the car? 
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06-13-2007, 06:49 AM
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Join Date: Apr 2007
Location: EUROPE
Posts: 43
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Hi, on the SC (not sure about 911s) the torsion bar has 40 splines on the inner end and 44 splines on the outer end.Moving the inner end 1 spline makes a difference of 9° which means about 8 mm. ride height.Moving the spring plate on the bar's outer end makes a difference of 8.18° which means about 7mm. in ride height. A 1° change in spring plate angle makes about 1cm. change in ride height. All very theoretical......I did mine about 4 times till I got it right.
Cheers, Mike |
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06-13-2007, 06:52 AM
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Join Date: Jun 2004
Location: Rio Rancho, New Mexico
Posts: 1,325
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The arm length is close to 18 inches.
Thus a 36 inch circle circimference is 113 inches. Divide that by 360 degrees and you get .314 inches per degree. Or 8mm/deg. To clarify Swissmade's explanation, rotating the inner splines one tooth and at the same time rotating the outer spline back one tooth will result in a net change of 9-8.18=.82 degree. .82 times .314 equals .257 inches. Or 6.5mm. Really it's simple math. It just gets confusing under the car assembling and checking the height, then redoing it to get it as close as possible.
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DOUG '76 911S 2.7, webers, solex cams, JE pistons, '74 exhaust, 23 & 28 torsion bars, 930 calipers & rotors, Hoosiers on 8's & 9's. '85 911 Carrera, stock, just painted, Orient Red |
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06-13-2007, 07:55 AM
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Join Date: Oct 2005
Location: Capistrano Beach, Ca.
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Thanks guys, that's just the kind of information I was looking for.
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L.J. Recovering Porsche-holic Gave up trying to stay clean Stabilized on a Pelican I.V. drip |
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06-13-2007, 07:13 PM
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