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4L60E Transmission - Automatic Rabbit Hole - Jp Magazine

Pete Trasborg Brand Manager, Jp

Using our normal bull-in-a-china-shop approach, we were able to get the wrong transmission behind an engine that it wasn’t designed for. Of course, we didn’t know that at the time, and built the transmission mount, mounted the T-case, and hooked up the shifter cables. But that wasn’t all. We also had custom driveshafts built and had them half installed when we realized we hadn’t bolted the torque converter to the flexplate. So we stopped in the middle of the front driveshaft install to discover that the bolt holes in the torque converter didn’t line up with the flexplate.

But wait, this transmission was behind this engine before. It was an LT-1 and a 4L60E. Those should go together like frat guys and beer kegs, right? As it turns out it is a little more complicated than that, and over the course of a couple of months with Dave Dibs at Orange County Transmissions, we learned way more about the 4L60E transmission than we ever wanted to.

Once we learned that there were four distinct versions of the transmission found behind V-8s, we decided it would be a great story if we could tell you what year/make/model GM vehicle you needed to rob a transmission from in order to bolt it up to your swapped-in small-block GM V-8 in your Jeep. Unfortunately, GM phased the early version out, even as it was phasing the later version in. And if that wasn’t enough, there were also the same platforms from the same years that used different versions of this transmission -- and these may or may not work with the engine you have. Regardless of not having a straight year/make/model cheat sheet, this is a good transmission with a low first gear, useable overall length, and good strength and durability. So, who’s on first? Let us try to make it way clearer than mud.

PhotosView Slideshow

Many people tell us that the big differences between the versions of the 4L60E are the cases and what engines the transmissions came behind, but OC Trans poo-poos that idea. They tell us that when you boil off all the other junk, the big change is right here—in the input shaft and drum assembly. The later model unit is seen on the left. The later model shaft has a larger input diameter and spline count, and it is slightly longer than the older parts. The associated pump with the later model input is also bigger and moves more fluid.

Only the newest 4L60E transmissions have the input shaft on the left, with some removable bellhousing, six-bolt rear output units running the earlier shaft to the right. The overall length of the transmission with the shaft on the left is also about 5⁄8-inch longer than the one with shaft on the right. And that later style of 4L60E ran from ’98-up.

Without yanking the torque converter off the transmission, an easy way to tell the difference between an early and a late 4L60E is by looking at the nose of the torque converter. The early torque converter has an indentation around the nose (arrow) that centers in the crank, whereas the later one sticks out about 1⁄2-inch past the face of the converter. You can see a later LSx converter in the lead photo for reference.

It shouldn’t have been possible because of the taller torque converter, but we did it. Dibs at OC tells us that normally when you force the late transmission onto the early engine like we did, you tend to shove the torque converter into the pump and that often destroys the pump or other parts inside the transmission. As it turns out, he ended up pulling it apart, but we’d managed to not kill anything so no rebuild was necessary. OC Trans showed us some upgraded parts in our transmission, as well as some parts that they prefer to use to get built 4L60Es out for less than we have in this one. In the end, we decided to keep what we had because it wasn’t broken. But, if we ever do destroy it, our first stop will be right back here for a rebuild and upgrade.

It is possible to go from an earlier engine to a late trans- mission or vice-versa by swapping bellhousings, input shafts, pumps, and torque converters, but that will run you $700-$1,000. Fortunately, Pace Performance stocked this GMP adapter kit (PN 19154766) for $206.95 that allows us to use our later LSx 4L60E with our ’94 LT-1. There is also a kit that allows use of the earlier 4L60E with an LS engine (PN 12563532) that comes in under $100 even after adding bolts. So unless you have to have your transmission completely rebuilt anyway, it is probably going to be less expensive to use one of the two adapter kits if you do grab the wrong transmission.

Identification and the Differences
There are four main differences to the 4L60E that started in some ’92 GM vehicles (Corvettes) and ran for the next couple of decades. It looks very much like the 700R4 that it replaced, but don’t be fooled. They are so close that the 700R4 was also known as a 4L60 after just a few minor changes. The 4L60E has no kickdown or TV cable, and all of that work is done through solenoids that are run thanks to a VSS at the back of the transmission.

PhotosView Slideshow Like the transmissions before it, the original 4L60E had a one-piece case with a cast-in bellhousing and a four-bolt flange for a tailhousing or T-case. This one ran from roughly ’92-’96, and for obvious reasons might not be the best way to start when converting to a non-Chevy engine.

Like the transmissions before it, the original 4L60E had a one-piece case with a cast-in bellhousing and a four-bolt flange for a tailhousing or T-case. This one ran from roughly ’92-’96, and for obvious reasons might not be the best way to start when converting to a non-Chevy engine.

The next iteration included a removable bellhousing transmission that still used a four-bolt flange on the back end. Shown is a close-up of the four-bolt flange. While there are aftermarket kits to allow adaptation of this ’case to the six-bolt style that we are more familiar with, generally you are better off starting with a later case if you want six-bolts. The conversion for this four-bolt case is longer than starting with a six-bolt case. This transmission is sort of an odd duck to find, because not too long after came the one to the right.

This version of the 4L60E ran up until just a few years ago and is commonly known as the LSx 4L60E because it’s found behind Gen III and Gen IV GM engines. With a larger input and larger pump drive, it is better suited to the sort of abuse we dish out at low road and engine speeds. It also has a six-bolt flange on the back, making T-case adaptations easier and shorter.

The removable bellhousing, early input, six-bolt flange transmission rolled along around 1996, and is a much more common version than the removable bellhousing transmission it followed. The six-bolt flange makes it easier to adapt to many T-cases, and the earlier input and deeper bellhousing than its successor makes it easier to bolt to earlier one-piece rear main engines. But we slipped a ringer in with this picture. Look closely at the bellhousing, and you’ll see no bolt hole at the 12 o’clock position and holes below the starter are in different places than the ones in the bellhousing in the next image. This is a V-6 bellhousing. Buyer beware—it won’t work with your V-8.

Nomenclature
4L60E
4: Four forward speeds
L: Longitudinally mounted (there is also a “T” version (Transverse mounting, such as in a Corsica or Ciera))
60: Rated for a 6,000-pound Gross Vehicle Weight (although GM did put it in some larger trucks up to and over 8,000 pounds)
E: Electronically shifted

It is possible to go from an earlier engine to a late trans- mission or vice-versa by swapping bellhousings, input shafts, pumps, and torque converters, but that will run you $700-$1,000. Fortunately, Pace Performance stocked this GMP adapter kit (PN 19154766) for $206.95 that allows us to use our later LSx 4L60E with our ’94 LT-1. There is also a kit that allows use of the earlier 4L60E with an LS engine (PN 12563532) that comes in under $100 even after adding bolts. So unless you have to have your transmission completely rebuilt anyway, it is probably going to be less expensive to use one of the two adapter kits if you do grab the wrong transmission.

When 60 Is More Than 80
A lot of Jeep guys want to go right to the 4L80E for their porky or big-tired Jeep, but the fact is there are even four-door JKs running 4L60Es with no problems. The 4L60E is lighter, shorter, and has a better First gear ratio than the 4L80E does. While the 4L80E has less slip between Third and Fourth gears, it is hard to beat the First gear in the 4L60E for a rig that sees even occasional crawling. While there are other transmissions with huge followings and parts availability, more and more people are looking for that low First gear and Overdrive. The 4L60E is pretty much the Chevy small-block of the automatic transmission world with more aftermarket support and parts availability than any other auto today.

When 60 Is More Than 80 Model 4L60E 4L80E Length (in) 21.9 26.25 Weight (lbs) 163.2 254 Gear Ratios First 3.06:1 2.48:1 Second 1.63:1 1.48:1 Third 1.00:1 1.00:1 Fourth 0.70:1 0.75:1 Reverse 2.29:1 2.07:1 Maximum Torque (ft-lb) 360 440 Removable Bellhousing? Yes No

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4L60E Transmission - Automatic Rabbit Hole - Jp Magazine

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