C1. Opinions please on which Auto Trans...

[Chuck S.]

Re: Clem, that's interesting...

Dick, if the other problems can be addressed, the Corvette 700R4 would have a nice torquey first gear to get the train moving; but, it will also probably have a bigger torque step-down when it shifts to second...maybe not an issue at that point.

[Dick W.]

Re: Clem, that's interesting...

White haired "old Dipsticks" probably will not be a doin' any "jackrabbit" type starts. Too hard on the heart. Therefore he probably would not need the deeper reduction.

[Dennis C.]

Joe, I checked the number/s...

Two listings start with M... MT1 and MX0 BTW, this '92 came equipped with the "locking" transmission dipstick. If the transmission number (ie 700-R4) is not followed with an E, does that mean you don't need a computer onboard. Thanks for your help.

[Terry M.]

Re: Joe, I checked the number/s...

Joe will probably do better with this one, but my option book (4/1998) shows MT1 = Auto 4 spd, HMD, 4L80-E. MX0 = Merchandising code, Auto provisions O/D

At some point the name 700-R4 became 4L60 (with almost no internal changes) which later became the 4L60-E (which has some internal changes from the 4L60).
At some point the TH 400 became 4L80 (with overdrive added, obviously) which became 4L80-E. This is not to say that a newer generation can be changed for an earlier generation. In some cases they can, in others control issues will develop even between different years of the same generation.

4 = number of forward gears
L = Longitudinal - for rear wheel drive
T = Transverse - for front wheel drive

60 - 80 = I think this is the diameter of the main shaft, or input shaft. What is important about this number is that, generally, the higher the number the stronger the transmission.

E = electronically (Powertrain Control Module) controlled transmission.

"If the transmission number (ie 700-R4) is not followed with an E, does that mean you don't need a computer onboard." It only means that the transmission is not controlled by the computer. There are other functions of the computer - timing the engine, or delivering fuel for example - that may be needed.

[Joe L.]

Re: Joe, I checked the number/s...

Dennis------

Your transmission is the 4L-80 (4 speed equivalent of the old 3 speed THM-400).

GM Powertrain transmission nomenclature changed in the early 90s. The THM-400 became 3L-80, the THM 700R4 became 4L60, and so on. With the new nomenclature, a non-"E" suffix transmission model indicates a transmission that does not require computer control or interface. The engines used with any of the new-nomenclature transmissions DO require computer control. The "computers" used for these are called ECMs or Engine Control Module.

In the 1993-94 period, the electronically controlled transmission began to be phased in. These transmissions use the same primary nomenclature as before (i.e. 4L80). However, the "E" suffix is added (i.e. 4L80-E). At the same time, the old ECMs became PCMs (for Powertrain Control Module) and they control both the engine AND transmission.

The 4L80, 4L80-E and the new 4L85-E are the strongest transmissions manufactured by the Hydramatic Division of GM Powertrain. For a 4 speed automatic, these are as good as it gets. Period. For a 3 speed automatic without overdrive, the THM-400 is as good as it gets. Period.

For the absolute strongest automatic (compatible for use in a light truck or car, of course), the Allison 1000 is THE one to have. Period. The Allison 1000 is manufactured by the Allison Division of GM which has rather recently, I believe, been merged into GM Powertrain. To install the Allison 1000 in a passenger car, though, would require rather massive modifications and adaptation. This is a LARGE transmission. But, it's THE ONE!

[Joe L.]

Re: Joe, I checked the number/s...

Terry-----

You've got it right. However, while the MT1 designation now denotes a 4L80-E, in 1992 it designated the plain 'ol 4L80. I don't think the electronic variant of this transmission had been released yet.