went to the track this weekend and had some shifting issues on my 4l60e. i logged the trans with datamaster and found the following. if i leave the car in overdrive or drive and take it down the track this is what happens (keep in mind all my rpm kickdown points are set at 6200 and my rev limiter is at 6700):

1>2 shift at 36 mph 5014 rpm
my mph 1>2 shift is set at 36 so once i hit that speed the trans switches the selected gear but does not actually shift.

2nd gear: rpms keep rising from 5014 to 5944 before they drop to 4746. this is probably because the mph has been met but the actual shift does not happen until 6200 rpm is met

2>3 shift at 73mph 5423 rpm
again my mph is set at 73 so once i hit that speed the trans switches the gear but does not actually shift because i assume it is awaiting the 6200 rpm setting before it actually shifts

3rd gear: rpms keep going rising from 5423 until they smack the revlimiter (6700 rpm) a couple of times. the rpms finally settle down to about 4024. so the car doesn't shift even after the set rpm is met like on the 1>2

all i want is for the car to shift on the 2>3. i have tried lowering both the mph and rpm way down using tunercats and still i have the same problem. i even lowered the shift time to have it shift faster and still nothing. i even tried shifting manually and adjusting the linkage and still nothing. the problem ONLY happens at WOT. this has me believing it is computer related. the fluid is fine and it doesn't smell burnt or clutchy at all. anybody have some suggestions. the tranny was rebuilt a little less than a year ago and has a 3K stall.

 

well i tried upping the line pressure and making the shift time faster and unfortunately no results. also tried lowering the rpm way down so the car would shift my mph and no results. tried lowering my mph way down and no results again. could my pcm be damaged in any way? i'm going to try to get another one and upload my tune to test it out. i've just about tried everything else tuning related might as well try another pcm to see what happens.

 

If you have the mph setting low enough try lowering the rpm threshold 200rpm at a time until you get it to shift. You might want to double check the kickdown tables also. I set them with the same values as the other tables.

I think I have seen the rpm threshold settings a 1000 rpm below the actually rpm that the shift takes place.

 

Your 3-4 clutches aren't coming on quick enough and/or not holding. Was it rebuilt back to stock specs, or was it a race oriented rebuild. What 3-4 clutches were used? What 2nd servo was used? What modifications were made to help the 3-4 clutches? (There are about 6 total, just for the 3-4 clutch apply).

Frank
CPT

 

it was a race oriented rebuild. i dropped the car off at the tranny shop the day before yesterday. when I pick it up I'll ask exactly what they did. i forgot the specifics when i was told what they do in their rebuilds since it was a lot of stuff and was almost a year ago. i had done my research and what they do as part of their rebuilds was inline with what the 4l60e guys were lisiting as part of their rebuilds. alot of stuff goes into these things to make them ready to handle a beating. i think heat may have had something to do with it. i had logged a couple of track runs and the trans temp reached 230 on one even with the cooler.

 

okay so it appears that the tranny is fine as far as clutches, bands, and servos go. the problem seems to be valve body related. they are currently going over it to check for internal leaks and valve issues. will keep everyone updated.