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Torsion bars.

How do they work? I am curious.

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1984 944 N/A
1996 Golf Gl
Drive fast. Take chances.

If you can't dazzle them with brilliance, baffle them with bull. - W. C. Fields
Old 10-19-2003, 03:57 PM
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how do you find the spring rate?
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1984 944 N/A
1996 Golf Gl
Drive fast. Take chances.

If you can't dazzle them with brilliance, baffle them with bull. - W. C. Fields
Old 10-20-2003, 10:51 AM
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From another source:

A wheel rate is the effective spring value when taking into consideration the placement, construction, and type of the sprung materials.

Torsion bar diameter is expressed as the effective diameter. Hollow bars will always be advertised with their effective rate which may not be the actual O.D.

Here's the equation: x = desired overall wheel rate, y = T-bar wheel rate: "(x - y)/.56 = linear coil-over spring rate" or " less divided by 56% equals linear coil-over spring rate"

EXAMPLE: OEM 23.5mm T-bar = 126#, desired overall rear wheel rate = 400#

(400 - 126)/.56 = 489 this means you'll need a 500# coil-over spring to achieve the 400# wheel rate.

Also:

There is a torsion bar value table, or you can devide the Torsion Bar diameter by 2420 and get the effective 'wheel rate'.

example: 23.5 / 2420 = 126 ft./in.
24.5 / 2420 = 149 ft./in.
25.5 / 2420 = 175 ft./in.


Changing or re-indexing the torsion bars on a 944 is a MAJOR job. Been there done that.

Good luck.
JM
Old 10-21-2003, 12:35 PM
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does the compositon of the metal the torsion bars are made of change the 2420 constant? What do they use in racing applications?
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1984 944 N/A
1996 Golf Gl
Drive fast. Take chances.

If you can't dazzle them with brilliance, baffle them with bull. - W. C. Fields
Old 10-21-2003, 11:33 PM
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I'm sure the material will have an effect... how much?...I don't know...I'm pretty sure all torsion bars are made from a type of 'spring steel'.

A stock setup for an early 944 would be:
Front Springs = 160 lb. (spring rate = 91 lb.)
Rear Torsion = 23.5 mm (spring rate = 126 lb.)
Front Sway bar = 21.5 mm
Rear Sway bar = 14.0 mm

Several of the cars in the 944Cup are set up very close to the following:
Front Springs = 400 lb. (spring rate = 225 lb.)
Rear Torsion = 30 mm (spring rate = 335 lb.)
Front Sway bar = 27 mm
Rear Sway bar = 19 mm (M030 Option, 3 position adj.)

New springs and struts up front lowered the nose about 1 in. When we installed the new torsion bars, we had to re-index them, to lower the rear a like amount, and keep the car level. The car is now about 5 in. off the ground.

I'm sure this setup would be too stiff for street use. On a smooth track like VIR it's great, at Summit Point it rattles my teeth.

Good Luck
JM

Old 10-22-2003, 11:44 AM
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