October 21, 2020
4T60-E Shifting Information
Last Updated: December 14, 2004
1st : 2.921:1
2nd : 1.568:1
3rd : 1:1
4th : 0.705:1
FDR : 2.93:1 (FR2) or 2.97:1 (F79)
As many of you know this is a combination of 1st and 2nd gear and holds first gear longer at part throttle. Most of the time the 1-2 shift will occur around 5,000-5500 rpm. Once in second, it will not downshift to first as long as you are above 20 mph. You cannot hold first gear to the rev limiter; it will shift at 5000-5500 rpm, every time, no matter what you do.
This is third gear, which is perfect for dyno runs with its 1:1 ratio. The 1-2 shift seems to be around 5600-5650 rpm, this is good for drag racing, with the 1-2 shift barely past peak power, (5200 rpm) (I'll bet most modded 3100s are higher than that) every rpm is needed. Downshifts happen just below 3,000 rpm for both 2-1 and 3-2. When I am in town, I am in this position to eliminate the constant shift to 4th, and to make an attempt to keep my transmission alive as long as possible.
Cruising gear, only useful for gas mileage.
How to Drag Race the 4T60-E
- Launch in "D", this gives a few extra hundred rpm for the 1-2 shift.
- After the 1-2 shift, slot back into L to hold second gear across the line.
This method has worked for me very well. I ran 16.112 @ 83.89 mph, with just the intake.
How to Auto-x the 4T60-E
I haven't tested it yet, this is just theory, but it makes sense to keep it in "L", it won't shift into second until 40 mph at the earliest. A good thing for short courses, longer and higher speed cones become tricky. You often get stuck at low rpm or a sudden downshift.
How to do a top speed run with a 4T60-E
Unplug the vehicle speed sensor (VSS). This doesn't work as well as it could. It takes a moment for the computer to figure out to shift into second. You can smack the rev limiter in 1st doing this (only way I know how, I don't know why you would want to). When the computer figures out what is going on and it shifts into 2nd, 2 and 3 are the only gears you can select. You have to do this by manual selecting D or L. The computer will not shift unless you say so. OD also doesn't work; when you select OD it appears as if the torque converter fully disengages. As far as OBD-II 3100s go, this is the only way to get by the 108 mph governor.
*This requires a scan tool to clear the code. Most shops charge for this if you don't have your own. The DTC will clear itself after the VSS is reconnected and the car is driven for a bit, but the SES light won't go out immediately *
Also do it on a road where your not going to hurt anyone.
I pulled to 5600 rpm in 3rd with the 3100. That works out to 135 mph, which is a bit high because of tach error and the torque converter is never fully locked. I am assuming somewhere in the neighborhood of 130-132 mph.
Recently I went out with the new motor and a GPS receiver. I clicked over to 140 mph at 5950 rpm in third gear with a slight tailwind (10-15 mph). I could not shift into 4th gear as the VSS DTC was set.
I gained an additional 8-10 mph on top speed with a simple motor swap. Who says 3400s don't have more top end?
BerettaSpeed.com will not be held responsible for damages incurred to your engine, transmission, or vehicle when disconnecting your VSS. Please obey local laws and make sure your tires are capable of speeds beyond the factory governor.
contributed by: Canada
[ 992 views |View For Printing ]