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RE: How stuff works --> Differentials

To: <triumphs@autox.team.net>
Subject: RE: How stuff works --> Differentials
From: "Jim Muller" <jimmuller@pop.mail.rcn.net>
Date: Wed, 29 Oct 2003 12:19:39 -0500
References: <3F9D3FC8.7030809@attglobal.net>
Sorry, I didn't slog through all the notes on this subject.  Been too 
busy at work and other stuff.  Irregardless and FWIW, on 27 Oct 2003 
at 10:22, Randall Young wrote:

> Because of the gears involved, there is a torque
> reaction at the rear that tends to lift one wheel.

The lift of one wheel, or to put it more accurately, the difference 
in the traction at the road between L and R wheels during a straight-
line start is caused by the difference in downforce.  Some of that 
may be due to the loading in the car (heavy driver, empty passenger 
seat), but much (most?) of it is due to the torque of the driveshaft 
on the diff casing.  Therefore it happens with a solid axle but NOT 
with IRS.  With a sollid axle, a torque on the diff casing on a 
longitudinal axis will lift one wheel and push down on the other.  
With IRS, which includes the Spitfire and GT6, the the diff casing is 
held by the frame, so torque on it does not affect the wheels.  (Ever 
see My Cousin Vinny?  If GM had ever used IRS on those cars that last 
courtroom scene wouldn't have worked!  Or have I totally 
misrememembered it?)

-- 
Jim Muller
jimmuller@pop.rcn.com
'80 Spitfire, '70 GT6+




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