700r4 Transmission

700R4 Transmission

The 700R4 transmission is an automatic transmission with overdrive (AOD).  It uses the turbo-hydramatic technology that was developed and produced by General Motors.  The 700R4 transmission was first introduced in 1982 and was used in several Chevrolet and GMC vehicles.  The non-electronic version of the 700R4 transmission was produced through 1992 and can be found in vehicles as late as 1993, however somewhere around 1990 it was renamed to the 4L60.

At this point electronic controls were added to the transmission, making it a 4L60-E.  The 700R4 transmission remained a staple transmission in GM’s line up in the traditional or electronic version until 2001, when it was replaced with an updated version known as the 4L65-E.

The 700R4 transmission is a highly sought after aftermarket transmission, primarily due to its low first gear, with the ability to retain an overdrive for comfortable highway driving.  It has a very strong aftermarket following and many aftermarket parts can be picked up for it.  Allowing you to add anything from a shift kit, to horsepower upgrades (to make it withstand more horsepower).

A common question is rather or not the 2wd version of the 700r4 transmission can be adapted to work in a 4wd.  The answer is yes, but at an expense.  Since the tailshaft is longer on the 2wd version you will need to do one of two things.  You can buy a special adapter that’s thicker to account for the extra length of the tailshaft (not recommended), or you can remove the tailshaft from your 4wd version and install it in the 2wd.

When searching for a donor 700R4 transmission it is recommended that you get one out of a vehicle that is, at a minimum, later then 1984.  Prior to 1984 they were manufactured with a 27 spline input shaft, but that was later updated to a 30 spline shaft to better withstand the power of the Chevy small block v8’s.  There were also a number of other upgrades that occurred between 1984-1987. So the 1987 and later 700R4 transmission is usually the most desirable.

Through its entire production cycle the 700R4 transmission always had the same gear ratio, this gearing ratio was: First – 3.059:1, Second – 1.625:1, Third - 1:1, Fourth (aka overdrive) – 0.696:1 and the reverse was 2.294:1.  It is a very desirable transmission, and one that you can’t really go wrong with.

700R Transmission / 700R4 Identification

The 700R4 transmission is easily identified by taking a peak at the oilpan. The pan has a rectangular shape that is longer front to rear than side to side, and is held on by 16 bolts.  The 700R4 transmission was offered in both a two-wheel drive and four-wheel drive variety.  The 2wd version has a longer tailshaft, and can be seen in the first image above, while the 4wd version has a shorter output shaft and different tailhousing that allows you to bolt up a transfer case.

For 700R4 identification it's best to pick a model that's made after 1987.  When selecting, try to make sure that it has 30 splines.  Then take a look at the ID numbers on the transmission.  The best way to tell if it's an 82-84 model is to look at the ID.  It will look something like "9 TA Y O0 M 12 N", if it's a 85-86 model the ID looks like "6 MD 146 A", 87-88 looks like "7 YK M Y 45335678-141 A" and if it's 89 and later it looks like "2 YD M 2 145 C". 

The first thing you need to do when identifying by the serial number is to find the series that it belongs in (the number will be different from those shown above, but the pattern is the same).  Then look at the first number, and that's the year it was manufactured.  IE if it's an 86, the first number is a 6 in it's pattern, and a 92 has the first number of a 2 in the example above.

Around the 1996 area, a bolt-on bellhousing was released, so if you see one with a detachable bellhousing you know that it is (was) more than likely originally a 4L60-E and not a 700R4 transmission.  There are several how-to articles out there on the internet on how to convert the electronically controlled transmission back to mechanical, which is often more desirable for hot-rod scenarios.