4L60E 2/3 shift

[BigVin]

I have a 96 4L60E with 2200 stall converter and a TCI 377500 controller behind a small block. 1/2 and 3/4 shifts are firm and quick. 2/3 shift is firm but lags. There is a split second from when I tap the paddle for it to shift. I would like to know if there is something that can be done to quicken the 2/3 shift in the computor or in the valve body.
Thanks in advance

[Throttle]

My tranny is built to the hilt and it still has issues going into 3rd..

[Steve Chryssos]

Vin,
There's a lot going on, internally, to make the 2-3 shift happen. It's normal for a stock trans to take longer on the 2-3 shift. The stock blueprint and calibration of the transmission's hydraulic and mechanical systems is holding you back. It's a matter of clearances, fluid volumes, etc--not hard parts. It's those little details that can't be described as bulleted points in an ad. Those details separate true master builders from your stock trans or one built by a shop without the right know-how. It's in the blueprint and calibration.

My Bowler 4l65RR shifts quickly at all throttle angles, speeds and for all gear changes. Every gear change is quick tug without being harsh. Oomph! Like that only faster. And, not 30 minutes ago, we test drove Vinnie's car with its new Bowler 4L80E-1000. And it shifts just as good. I'm actually surprised. I convinced myself that 80's just cannot shift fast. The trans we pulled would take a day and a half to shift in automatic mode. And in paddle shift mode, inputs were difficult to anticipate. Trans redline was set at 4800 rpm to get WOT upshifts at 6500 engine rpm. By comparison, the new Bowler 4L80E-1000 has the trans redline set at 6000 rpm--only a 500 rpm difference. It's in the trans.

That's bad news if you are not in the market for a new trans. But there's some good news. If you want, call me next week and we can apply some tricks to the TCU. The electronics can only do so much. It's not the right way to get the job done, but it helped a bunch on my old trans/tcu (Before I switched to Bowler and Compushift).

In the future, find yourself a good builder and discuss the 2-3 shift specifically. Let him take a test drive in it's current form. Hydraulic/mechanical calibration and blueprinting techniques are secretive stuff--especially in the message board era. So don't expect a detailed response unless it's in a one on one situation.

[burnoutbruce]

Call RPM

[Jake's Performance]

2-3 shift on a 4L60E is determined by a bunch of factors and like an engine or a car the "combo" is important to the final product.

On a 700-R4, 4L60E, 65E, 70E (all the same family) and 200-4R, as well as many other transmissions, C-4, 727 TorqueFlite, Powerglide, etc the band timing is critical.

Instead of using sprag (one way clutch) and having a clutch over clutch shift design, you have a synchronous shift design.

What this means is that instead of one clutch applying after another and a sprag overrunning, you have to release one clutch (or band in this case) and at the same time apply another clutch (or band).

If both friction elements come on at the same time, you have a bind up, which = burnt friction elements, broken parts, bad shift quality, and a short life.
If you release the 2-4 band too fast on a 4L60E then you have a flare.
This is actually a momentary return to 1st gear. So instead of a 2-3 shift you have a 2-1-3 shift. Also brutal on the frictions.

It takes some experimenting to make this shift perfect and it's difficult to ever make it a firm shift at all throttle angles, although IMO the electronic control of the 4L60E makes it easier than the 700-R4.

Your servo size plays a role in the whole scheme, the valve body mods, etc.

The easiest thing to look at is see what the servo clearance is, if it's loose, it will soften the 2-3 shift due to a greater volume of fluid needed to kick the servo "off".

[BigVin]

Thanks Steve