bjankuski

I have a strange issue with my rebuilt 4L60E transmission, it drives fine and shifts fine at part throttle but at WOT it will not complete the 2 to 3 gear shift at WOT without hitting the rev limiter when the transmission is cool. I have to drive at least 8 miles to warm up the transmission and then it shifts from 2 to 3 at WOT with no problem. If the trans is still cool you can feel the band let go at the start of the shift at 6100 RPM but the 3/4 clutch pack will not engage unless I lift for a split second. The rev limiter is set for 6700 and it appears like the trans tries to shift but the clutchs for 3/4 will not engage quick enough.

Any ideas? The car is a 2000 camaro.

Monzsta

If you've installed a higher stall converter your shift points need to be adjusted as the new converter allows the engine to rev faster. Engine mods can do this as well. If you are tuning it yourself you have to "lead" the shift by a few hundred rpm. If you're set to shift at say, 6000 the transmission will not actually shift untill 6500-6700, (the 6000 is where you actually begin to shift) at which case you can run into the limiter.

01ssreda4

iTrader: (96)

Mine is close to the edge on 2/3 also, it seems to be a really lazy shift for the 4l60e. By on the edge I mean, when warm I command a shift at 6200, but the trans takes until 6500 to complete it and the car has a 6600 limiter. So Im only actually giving the trans 100 rpm of error time. The problem is, if anything changes to slow the shift or speed the acceleration I run the risk of being on the limiter. When the trans is stone cold, I have hit the limiter, then 20-30 degrees later its perfect every shift. The obvious fix here is know your window from commanded shift, to actual shift, then increase your window to account for other circumstances. Or just let your trans warm up before you hammer it. On the contrary, my 1/2 is command at 6400 and is completed by 6450. The 2/3 is just a slow shift for whatever reason, stock or built trans.

bjankuski

Thanks for the replies, the strange part is it works fine warm but goofy cold. I cannot really only hammer on it warm because I cannot drive 8 miles to warm it up at the strip. I can warm up the engine at the strip and the transmission warms up a little but not enough to shift correctly. I will try and lower the shift points down some more and see what happens.

01ssreda4

iTrader: (96)

Remember the mph must be met before the rpm. The shift is rpm based as long as the actual mph is above the commanded mph.

murphinator

iTrader: (2)

the old adage to fill a 4l60 1/2 quart overfull to avoid 2/3 shift issues may help you...

mrvedit

Often dropping the shift MPH by a few will solve the problem.
As mentioned going 1/4 to 1/2 quart over full often helps reduce slippage during the 2-3 shift.

Since you mention "lowering the shift point", does that mean you have HP Tuners or EFI Live?
If yes and you still have problems, you might want to log the commanded gear along with RPM and MPH to determine if the shift is commanded too late or the 3/4 clutch is slipping.
As you probably know, a slipping 2-3 shift due to a worn 3/4 clutch is the most common problem with a 4L60E.

bjankuski

This was very good advice, too bad I did not see it until I found this trick on my own, after four weeks of screwing around with tuning and transmission flow schematics. I tore the valve body and plates off at least twice looking for the problem and traced every circuit I could looking for a problem. By accident I overfilled the transmission by about a pint and what do you know, it shifted fine!! One week latter it is still working fine.

I am going to try a truck deep sump pan, and filter and see if this works fine without having to overfill the transmission.

Thanks