Re: Shifting the XJ-S

[Randy Wilson <randy@taylor.infi.net>]

>
>My xj-s shifts too soon, just like everybody else's.  If I start with the gear
>selector in 1, then move the selector to 2, and ultimately to D, I achieve a
>much more hearty acceleration, and better shift points.  This is fun, so
>it's probably bad for the transmission.  Will I tear up the car if I give in to
>the temptation to blaze away in first gear and manually shift up?

Normally, no. Manual upshifting will not cause problems. Manual downshifting
can cause some large stresses, but there are limits designed in to the
valve body to to keep it from doing a *really* stupid driver requested
downshift.

I said normally. Here's the catch. The relative shift points are controlled
by the vacuum modulator valve. The modulator also controls the shift 
"firmness"; how quickly it actually shifts. If all of this is working
correctly, at low throttle settings, the trans will shift early and
softly; sliding from one gear to the next without a big jolt. At high 
throttle positions, before kickdown, it will shift much later and harder.

 If whatever is causing your trans to shift early all of the time is also 
causing full time soft shift, then you run the risk of damaging the
transmission. If you run the engine up into the fat part of the power band
and manually shift, and the trans does a soft shift, then you will eventual
smoke the clutches and bands to nothing.



>
>--Steve


   Randy K. Wilson
     randy@taylor.infi.net

---

References:

• Shifting the XJ-S
• From: Steve Draper <s_draper@wcsr.com>

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