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View Full Version : C6 Servo Adjustment



Thomas C Potter
09-11-2006, 08:08 PM
I have little experience with automatics, so thought I'd ask before hand. My C6 was built with stronger internals, and the shop told me I could adjust the servo 3/4 of a trun max to soften the shift. Is this as simple as removing the 4 bolts, and then ??????????? I appreciate the time someone would take to provide a brief description of what is to be done.

VERN
09-12-2006, 07:32 AM
You can adjust the shift points by adjusting the vacuum modulator. Follow the vacuum line down to the modulator near the back of the pan on the transmission. Pull off the vacuum line. Use a small allen key wrench through the metal tube where the vacuum line was attached. (I don't remember what size allen key) Turn the screw inside the modulator. Tightening the crew I believe will make the shift later( firmer) and loosening the screw will make the shift earlier (softer). Don't make too big a change - 1/2 turn - at a time and see how the car drives

Thomas C Potter
09-12-2006, 06:42 PM
Thanx Vern

JACook
09-15-2006, 12:44 PM
the shop told me I could adjust the servo 3/4 of a trun max to soften the shift.

Hmm... Were they talking about adjusting the vacuum modulator? Or backing out the intermediate
servo band adjustment bolt?

If you want it to shift earlier and softer overall at part throttle, that would be the modulator. But this
won't affect WOT shifts. If you're looking for less whack from 2nd gear, particularly at about 2/3 throttle
or more, backing out the band adjustment a bit might help. I would take small steps though, say 1/4 turn
at a go, and definitely don't exceed 3/4 turn overall from where you are now.

The intermediate band adjustment is the sqare-headed bolt with locknut that's on the driver's side, just
above the manual linkage. C6 has only one band. The locknut has a molded seal on it, and it's usually
recommended to replace the locknut whenever you adjust the band. Most often I'll reuse the nut unless
the seal is mangled, but be aware if you reuse it, it might leak.

The normal procedure for intermediate band adjustment on a stock C6 is to torque the adjuster screw to
120 in/lb, then back out exactly 1 turn. But you'll find, depending on the builder and the application, this
can range from 3/4 turn to 1 1/2 turn. It'd be nice to know what your transmission builder recommends to
begin with, in case you need to start over, and also for doing periodic band adjustments.

thePunisher
09-16-2006, 04:20 AM
yeah the servo cant be adjusted...but the intermediate band can. the servo applies the band.