jprophecy

Just got a freshly built 4l65e in my GTO. Its got very fast and firm shifting, definitely not like the 4l60e it replaced. The builder said its more than likely just because of the extra clutch set and the upgraded shell, and that Im not used to it. Now I dont mind the harder and faster shifting, I believe it will only benefit me at the track, but is it going to be a lot harder on my trans and motor mounts? Or any other drive line components?

mrvedit

The extra 7th 3/4 friction in a 4L65E will have no effect on the shifting; the shell makes absolutely no difference either.
Complaints about harder shifting are usually about the 1-2 shift so let me concentrate on that.
First, was a shift kit installed? If yes, which one? If a B&W, remove it immediately before the trans is damaged. (It disables the 1-2 accumulator.)
Next, is this otherwise a stock rebuild of a 4L65E?
Also, scan for codes - a 1870 code (TCC slip) will force the PCM to set maximum line pressure in the trans, giving you very firm shifts. Others codes will do the same.

Finally, hook up a pressure gauge to the trans. In drive at low throttle, stock line pressure is around 60 psi, with a shift kit around 90 psi. I suspect you are running much higher. If true, there are more things to check and typically easy to correct.

Also, what converter are you using and what stall is it? A high stall converter will mask the effects of a too-firm shifting trans. If you have a stock converter and a proper shift kit was installed, it might simply be firmer than you expected.

jprophecy

I have a 3600 Tripple disk stall. Viggilant I believe

mrvedit

Under light throttle, shifts should feel very mild with that high a stall.

Still need to know if any shift kit was installed.

jprophecy

No there was no shift kit installed, I did have a check engine code when the 4l60 went out, but there is no code at the moment. I believe the previous 4l60 had some tuning done too it all I can remember though is 30% stall slippage.

mrvedit

Perhaps it was tuned for max pressure across the board because the trans was starting to slip?
The only reliable way to figure this out is by connecting a trans pressure gauge;
if the pressure is too high at low throttle, we can then figure out why.

A trans shop can connect a guage for you. Or you can buy one on ebay for about $45 with shipping. It comes with a long hose so that you can view it while driving and testing things.

jprophecy

I dont think that was the case because it was tuned three years ago by modern muscle when I had Long tubes the stall, and 3.91 gears installed...... The trans was fine back than. I got probably 300-400 passes out of the track be fore the 4l60 started slipping and blew. I figured everything should work the same putting a new trans in.

Its not crazy hard, just feels like someone took a hand held tuner and raised the line pressure some. Is that necessarily a bad thing? Ive heard from older guys that raising the pressure for harder faster shifts is better any way. Transmissions unfortunately are an area thats not really my strongest field in mechanics.

fasteddy

Fast and Firm?
Whats wrong with that?

I guess it depends how you like it.

I just had a 4l60 redone too and had to re-tune it....cuz 1st to second was snapping heads off.
Line pressure, TQ Mgmt, Min speed for shift, shift time...bla bla bla.

All the variables need to be "tuned" for the new equipment and your preferences.

Like I like no (0) TQ Mgmt....but had to put some back in to smooth out that 1st to 2nd shift into warp drive. I had to change other things too because it was definitely operating differently with the new parts.

I didn't realize I was going to have to do that.....but then again....I tuned a trans with 100K miles on it too.

Gas mileage increased....I guess thats good.