Spotter’s Guide: 4L60E Transmission

By Jeff Smith

It’s all about control. The automotive world is increasingly regulated by digital electronics, and hot rodders might as well take advantage of these amenities. If you look at the progression of new cars for the last 30 years, it’s all about digital management of every aspect of the automobile — including automatic transmissions.

This story will look at the evolution of the 4L60E, which is essentially a digitally controlled 700-R4. We’ve done the research so you don’t have to wade through all the inaccurate chaff to pick out the seeds of the best 4L60E. We’d also like to thank Jimmy Galante at Racetrans in Sun Valley, California, for his technical guidance with this story.

Let’s start with a brief history. The original 700-R4 was built in 1982 as a Corvette four-speed automatic with overdrive. This gearbox is different because it applies an overdrive to First gear to create Second. Third gear is 1:1, with overdrive again engaged to create Fourth.

This first version was designed with a bolt-on extension housing and employed a throttle-valve (TV) cable intended to signal engine load to the transmission via throttle position, instead of a using engine vacuum. Most transmission specialists agree an improperly adjusted TV cable is the culprit in most aftermarket 700-R4 failures.

In 1993, GM wisely converted to electronic control, eliminating the cumbersome TV cable while changing its nomenclature to 4L60E. The numbers decipher like this: 4 is the number of forward gears, L (longitudinal) for rear-wheel drive, 60 equates to a maximum 6,000 pounds of gross vehicle weight (GVW), and E for electronic control. Later transmissions were upgraded as 4L65 and 4L70 for use in heavy-duty trucks.

The 4L60E has now been in production for more than two decades and has experienced multiple performance updates that affect interchangeability. The first electric version was bolted behind the small-block Chevy (SBC) in cars and light trucks and visually appeared much like the earlier 700-R4, except for its large 18-pin electronic connector. The next major change was a six-bolt extension housing in 1993, compared to the original four-bolt.

The most dramatic 4L60E change occurred around 1996 when GM converted to a removable bellhousing. This move allowed adapting multiple engine bellhousing patterns to the same case. For torque converters, the earliest 700-R4 transmissions used a 27-spline converter. Later 1984-’97 700R4 and 4L60 versions were of the 298mm family line, with a 30-spline input and a 1.70-inch diameter hub.

With the introduction of the LS engine family in 1998, later 4L60E transmissions employed a third different input, also 30-spline, with a larger 300mm torque converter that is substantially thicker (about ¾-inch) than previous versions. There followed a fourth and most recent 4L60E evolution that accommodates an input shaft reluctor that does not effectively interchange with earlier converters.

Trans Swapping

Because LS engine swaps into older muscle cars has become a foundation in the performance world, this means the 4L60E is heavily ingrained in this parts dance. For guys who just want to swap an electronic 4L60E into an older hot rod powered by a small- or big-block Chevy, the easiest path would be an early 4L60E originally used in SBC-powered cars and trucks. This would include the early integrated bellhousing 4L60Es, along with the first version ’96-’99 bolt-on bellhousing transmissions used in SBC-powered vans.

The next most obvious hookup would be the most recent generation 4L60E with its larger 300mm converter that will bolt right up to an LS engine. In most cases, you can use the 4L60E trans with its 298mm style converter behind a normal, six-bolt LS crank flange engine (4.8L, 5.2L, 5.7L, 6.0L, and 6.2L). Truck engines such as the 4.8L, 5.3L, and 6.0L used a dished flexplate to place the starter ring gear in the correct position. The 298 and 300mm references are to converter diameter — 300mm equals 11.8 inches.

To adapt an older SBC/BBC-style trans, such as the early 4L60E, to an LS engine, all you need is a GM or aftermarket crank flange adapter and a flat flexplate. The adapter mounts between the crankshaft and the flexplate with the center portion of the hub protruding through the flexplate. This extends the short LS crank flange by 0.400-inch to the 1.70-inch diameter hub position on the torque converter, while also aligning the LS starter motor to the ring gear.

There is an exception to the above information. The 1999 and 2000 4.8L and 6.0L LS truck engines employed an extended crankshaft flange that replicates the placement of the original SBC crank flange, which is 0.400-inch closer to the converter than “normal” or flush LS cranks. In this case, the best option is to use a SBC-style 4L60E trans with a flat LS flexplate. Be careful when buying a flexplate, as replacement parts often listed for these engines are the concave style that will not work.

For those who desire to adapt a late model LS style 4L60E to a small-block Chevy, the best approach is to find a 4L60E transmission originally built for the small-block Chevy. This trans will have the bolt-on bellhousing with the traditional SBC/BBC bellhousing pattern.

Builders, however, are often faced with using what they have or can buy cheaply. Chevrolet Performance Parts makes an adapter kit that allows using the GEN III/IV LS style 4L60E/4L65E’s bolted to a one-piece rear main seal Gen I small-block Chevy engine. The kit (PN 19154766) includes an aluminum spacer (roughly 0.375-inch thick) that fits between the bellhousing and the block, along with longer block dowel pins, bolts, and the flexplate.

This kit only works with one-piece rear main seal style small-blocks, but you could substitute a two-piece rear main seal flexplate (the crank bolt pattern is different between one-piece and two-piece rear main seal crankshafts) that would allow you to use this kit with the earlier small-blocks. It would also be possible to build your own spacer. TCI Automotive offers longer dowel pins.

Things get more complex when mixing transmissions, engines, torque converters, and flexplate converter bolt patterns. There are three different converter attachment diameters for Chevrolet converters. The earliest and most common TH350 and TH400 torque converters used either a 10.75- or 11.5-inch bolt pattern that is measured from the crank centerline to the center of one bolt hole and multiplied by two. LS engine converters use an in-between 11.1-inch bolt pattern. Thankfully, the 11.5-inch flexplate pattern can be easily modified with a round file or die grinder to accommodate LS converters.

For those wanting to swap a 4L60E into an earlier car, you also need to think about speedometers. There are several companies, such as ShiftWorks, that offer a cast aluminum tailshaft housing that will drive the original speedometer cable. This will cost between $500 and $600. Many of the stand-alone controllers will indicate speed, but this requires using their display.

Another option is to use the 4L60E’s stock VSS (vehicle speed sensor) signal to drive an electronic speedometer available from several companies, like AutoMeter, Classic Instruments, SpeedHut, and others. Or, you could use an electronic speedometer and drive it with a GPS signal. A different alternative comes from companies like Abbott or Speedhut who offer a conversion box that uses the VSS signal to command an electric motor that drives the stock cable speedometer. SpeedHut’s version is about to come online, and we are told the cost should be around $400.

As you can see, there are multiple variations on the 4L60E transmissions that make it very easy to wander down the wrong performance path. Mistakes are easy, especially if you are mixing and matching engines and transmissions. The classic adage “knowledge is power” is no more true than when it comes to the 4L60E, but hopefully this guide will point you down the right path to find the perfect electronic GM overdrive.

Trans Length Chart

This TCI chart calls out the different 4L60E transmissions and their lengths compared to a typical TH350. The bellhousing pattern refers to either small-block Chevy (SBC) or LS Gen III/IV engines.

Trans Tips

You can quickly identify later 4L60E versions by the RPO code cast into both sides of the case. It’s best to use more than one means to identify a specific transmission to avoid possible individual year idiosyncrasies.

*Weight with fluid, minus torque converter.

Parts List

Sources: Abbott Enterprises;abbott-tach.com, Auto Meter Products;autometer.com, B&M Performance Products;bmracing.com, Chevrolet Performance;chevrolet.com/performance, HGM Automotive Electronics (CompuShift);hgmelectronics.com, Painless Wiring;painlessperformance.com, Powertrain Control Solutions;powertraincontrolsolutions.com, Speedhut;speedhut.com, TCI;tciauto.com