c4 shift points

[enferno]

on the vacuum modulator . .do i turn the screw clockwise or counterclockwise to lower the rpm at which the tranny shifts?

thanks!

 

[dennis112]

on the vacuum modulator . .do i turn the screw clockwise or counterclockwise to lower the rpm at which the tranny shifts?

thanks!

I believe that you back it out CCW to decrease the rpm.

Irregardless, it is very easy to figure out since it is a very course adjustment. Back the screw out 2 full turns and take it for a test drive--be sure to put the hose back on or else it will act like it will never shift. If we went in the wrong direction, then turn it CW 4 turns (which overshoots where you began.) Fine tune from there.

 

[GoinBroke]

Dennis is right as always. CW lengthens the shift point to a higher RPM and CCW retards it. Just had to do this a couple weeks ago on my new tranny.

 

[enferno]

thanks!

 

[19stang66]

So what is a good shift point for a c4? Is it personal preference or is there a performance aspect too?

 

[C0V3R]

I believe that you back it out CCW to decrease the rpm.

Irregardless, it is very easy to figure out since it is a very course adjustment. Back the screw out 2 full turns and take it for a test drive--be sure to put the hose back on or else it will act like it will never shift. If we went in the wrong direction, then turn it CW 4 turns (which overshoots where you began.) Fine tune from there.

Would a leaking hose explain my c4 never wanting to shift up at WOT? I need to back right off after a WOT burst in order for it to shift up.

 

[dennis112]

Would a leaking hose explain my c4 never wanting to shift up at WOT? I need to back right off after a WOT burst in order for it to shift up.

Yes, a leaking/missing hose or a bad modulator will delay an upshift until you leave off the gas (or nearly hit redline.)

 

[dennis112]

Would a leaking hose explain my c4 never wanting to shift up at WOT? I need to back right off after a WOT burst in order for it to shift up.

Yes, a leaking/missing hose or a bad modulator "might" delay an upshift until you leave off the gas (or nearly hit redline.)

Of course you could have valve body issues too, but the modulator stuff is the easiest to mess with.