4l60 shift problems (at track)
Thread Starter
Teching In
Joined: Apr 2004
Posts: 13
Likes: 0
4l60 shift problems (at track) I have a98 trans am with stage 2 heads, 228/228 588/588 Texas speed cam,3500 tci converter,ported throttle body,and 373 gears. Driving on the street it shifts fine, at the track it bounces off the 7000 rpm revlimiter several times before shifting. You have to let off for a while for it to shift. The question is it dieing are in my tune?
TECH Enthusiast
Joined: Mar 2004
Posts: 647
Likes: 0
From: Australia
Even though you may command an RPM shift point at WOT at 6500RPM, in real life that may not be happening. You need to log your run and see both the RPM and MPH, plus determine the shift lag, Its a combination of all that must be balanced.
Shifting at high RPM becomes difficult to control due the TQ involved. You need to look at these things:
WOT shift RPM
WOT shift MPH
WOT shift lag (logged)
Shift pressure
TQ management and consequently timing retard
Only track time, patience, logging, reflashing and trial and error will solve this problem for you reliably. Otherwise its just a stab in the dark.
To guide you, heres what I would tackle first:
remove TQ management for the shift
increase line pressure by 10%
keep the shift at 6500RPM
log the MPH at 6500RPM
set the MPH shift at 3MPH less than that logged at 6500MPH
sync the base shift tables at 88/94/100% TPS with the WOT shift tables
Good luck
Shifting at high RPM becomes difficult to control due the TQ involved. You need to look at these things:
WOT shift RPM
WOT shift MPH
WOT shift lag (logged)
Shift pressure
TQ management and consequently timing retard
Only track time, patience, logging, reflashing and trial and error will solve this problem for you reliably. Otherwise its just a stab in the dark.
To guide you, heres what I would tackle first:
remove TQ management for the shift
increase line pressure by 10%
keep the shift at 6500RPM
log the MPH at 6500RPM
set the MPH shift at 3MPH less than that logged at 6500MPH
sync the base shift tables at 88/94/100% TPS with the WOT shift tables
Good luck
Thread Starter
Teching In
Joined: Apr 2004
Posts: 13
Likes: 0
Thanks for the replies. We are taking it to the track this weekend to try out both suggestions. There are some local guys saying that is what there's was doing before they went out. They said it was the 3/4 clutch pack. Thanks again.
