How To Identify Your 4L80e Transmission
The 4L80e transmission was introduced as the successor to the TH400. As a matter of fact, the transmission has been extant since 1991. This transmission is computer controlled and there are only very few transmissions that can compare to it especially if the process of elimination is applied. Like the 4L60e/700R4 twins, there has been quite some significant improvements since its introduction.
Consider the 4L80e as a TH400 enhanced with an overdrive gear. Both the TH400 and the 4L80e are legendary for their factory-built, bulletproof reliability. While the both transmissions tend to operate with similar specs, the 4L80e will require a new driveshaft especially when one needs to be swapped for the other.
This is majorly because it is a little longer (with just a few inches) from the TH400; a massive transmission indeed. To this end, it is essentially important to take accurate measurements of the tunnel size of the car especially if swapping will be involved. This is because it often requires a large tunnel size that is even larger than what the car may allow.
Of course, only the 4L80e transmission gets the overdrive gear, these transmissions are both designed to utilize the same forward gear ratios. Obviously, it will be no brainer to determine which is which, when observing both transmissions side by side.
Number of bolts
Another easy way to identify the 4L80e transmission is by the number of bolts it has on the pan. You can be sure to have identified this transmission when you count the bolts and get 17. As is the case with all longitudinal transmissions, bolt counting is always the easiest way of identifying them, as they all have a different number of bolts. However, it’s only the TH400 and TH350 that share the same number of bolts. 4L80e’s successor 6L80e has 20 bolts.
Availability of a computer control
If you don’t know how to identify your 4L80e transmission, you can begin by looking for a computer control. Your ability to determine whether it is computer-controlled or not will give an insight as to where it belongs. One good way to identify a computer-controlled transmission is by locating the circular wiring harness connector. So, from this point, you can easily determine where it belongs. Any transmission that does not possess this feature is simply classic and not computer-controlled.
Comparing the 4L80e transmission with 4L60e transmission
Identifying 4L80e transmissions is quite easy. These transmissions are generally designed with two-speed sensors which are located on the driver side. Unlike the recent units which have an upper both hole, early 4L80e transmissions do not have any top bolt hole in the bell housing.
While there are separate cooler lines (which are about 10-12 inch apart on the passenger side of the transmission) in the late 4L80e transmission, the early units have closely related cooler lines located in the front of the bell housing area. Like the 4L60e, the 4L80e utilizes an overdrive gear that is very much aggressive. Ultimately, the 4L80e is far heavier than the 4L60e, weighing 27 pounds more in weight.