GM’s 4L80E overdrive automatic is the latest in a continuing legacy of rugged Turbo-Hydramatic transmissions from Chevrolet. Fifty years ago, the TH350 and the TH400 transmissions were a new generation of dependable three-speed automatics from GM’s Hydramatic Division. The TH350 light-duty automatic introduced in 1969 was conceived for small-block V-8s while the TH400, introduced in 1964, with its higher torque capacity was engineered to handle big-block power.
At the cusp of the 1990s, GM changed the way it designated its automatic transmissions. The 700-R4 became the 4L60 that meant four forward speeds (4); and a longitudinal design (L); 60 for torque capacity, which would be a 6,000-pound vehicle weight rating. When these automatics became electronically controlled in the early 1990s, an “E” designation swiftly followed.
GM took the assets of these two transmissions, the TH400 and the electronically controlled 4L60E, and adapted them to modern technology: electronic control and stronger internals. The 4L80E, which entered production in 1991 for trucks, was conceived on the heels of the 700-R4 and 4L60, although it shares quite a bit with the tried-and-true TH400. Think of it as an overdrive TH400, which means it’s capable of handling gobs of torque compared to the lighter-duty automatics.
The 4L80E has gear ratios of 2.48:1 (First), 1.48:1 (Second), 1.00:1 (Third), 0.75:1 (Fourth), and 2.07:1 (Reverse). When the 4L80E was introduced, torque capacity was vehicles up to 8,000 pounds and engines producing up to 440 lb-ft of torque. The uprated 4L85E, introduced in 2002, is rated for vehicles up to 16,500 pounds and engines producing up to 460 lb-ft of torque. Adaptive learning technology enables the 4L80E/4L85E to “learn” your driving style and adapt to it as a result. If you’re installing a 4L80E/4L85E in a classic Chevy, controllers are available from the aftermarket.
Designed and built with the best performance parts available, the four-speed Street Smart 4L80E from Performance Automatic has an improved gear ratio spread for vehicles that need the most from their transmission. The Quik Connect Program is also included with all Platinum Transmission packages. Performance Automatic’s Quik Connect Program is a comprehensive program containing easy-to-follow instructional videos along with personalized technical assistance. It is personalized service needed in today’s high-tech hot rod world. The Quik Connect Program is tied to specific products, including the 4L80E, offered from Performance Automatic. These products will have a special designation with the part number. Once the customer registers the product, they will have access to the complete program.
Inside the Performance Automatic 4L80E are significant improvements that add torque capacity and durability. A hardened input shaft gets you off to a good start with greater torque capacity. Performance Automatic gives the 4L80E greater pump capacity for higher volume and pressure. It fits the 4L80E with Raybestos clutches and a higher capacity intermediate band for solid hook-up. Modifications are made to the valvebody for crisp shifts and precise shift timing. A heavy-duty sprag improves durability. A heavy-duty locking torque converter fitted with improved frictions eliminates slippage and excessive heat. Heat is a 4L80E’s greatest enemy. In short, Performance Automatic yields a 4L80E engineered to handle 700+ horsepower and comparable torque.
1. The Performance Automatic 4L80E is a proven street/strip (read: overdrive) automatic designed for big-blocks and high-power small-blocks, and the beloved LS. We’re building a 4L85E with uprated high-performance hard parts and frictions. The result is greater horsepower and torque capacity.
2. The 4L80E/4L85E looks like a lot of monkey motion inside. However, how power travels through this transmission is simple. We’re most interested in what Performance Automatic does to give the 4L80E greater capacity. Durability comes from better clutches and rugged bands, hardened input shaft, improved sprag, and five-pinion planets.
3. Performance Automatic begins with a hardened input shaft as a means to increasing torque capacity. Higher planet capacity is what comes next.
4. High-performance Raybestos clutches and bands are employed throughout the 4L80E. The bottom line is greater holding power. Greater clutch and band holding power means less heat and less heat makes for a happy and long-lasting transmission.
5. Transmission shops have different approaches to building. Some prefer to soak frictions in transmission fluid before assembly while others install dry. The logic behind soaking the frictions is to get an accurate read on clearances during assembly. Not all transmission builders will agree on this one.
6. Increased torque capacity comes from this 4140 steel billet forward clutch hub from Performance Automatic. The forward clutch is fitted with Raybestos frictions and plates along with a Torrington thrust bearing. The result is greater torque capacity, holding power, and smoothness.
7. This is the 4L80E’s four-pinion rear low gear plantary gearset. You can upgrade to the five-pinion planet, which improves torque capacity by spreading the load over a greater area.
8. The overrun clutch drum and new overdrive roller clutch are assembled using the new Raybestos clutches and plates. New bushings have also been pressed in.
9. This is the four-pinion overdrive planet for the 4L80E. The 4L80E and 4L85E both have four-pinion overdrive planets. The 4L85E differs from the 4L80E in that both the low and intermediate planets are five-pinion on the 4L85E, thus increasing torque capacity.
10. Servo sizing has a direct effect on band holding performance and slippage. You want the largest servo size available, which prevents slippage and unnecessary heat. A billet aluminum servo is suggested when power goes over the top. Stock servos tend to break in extreme power applications.
11. The direct clutch package gets a fresh complement of Raybestos clutches and upgrade apply piston.
12. Raybestos heavy-duty clutch frictions and steels are employed throughout each Performance Automatic 4L80E build. Clutch plates are heat-treated and can withstand heat much better than original equipment.
13. The 4L80E geartrain package has had all the clearances checked and have been carefully assembled by Performance Automatic’s professional staff. Here it is being loaded into the case, this is also when the front pump gasket is installed.
14. New bushings are installed throughout the 4L80E regardless of the condition of existing bushings. Each is coated with transmission assembly lube for a slippery start up.
15. Teflon sealing rings replace the old-school iron rings because they do not break. Installation is tricky. However, if performed correctly these seals outlast anything out there.
16. The front pump assembly has been checked for scoring and wear issues. The pump is then assembled and filled with assembly lube.
17. Front pump seal issues bite us in the posterior most. The seal flange must face the outside of the pump with the seal lip pointed toward the inside. Finally, the seal lip must be generously lubricated. The outside perimeter gets a super thin film of Permatex’s The Right Stuff.
18. The front pump assembly is then carefully guided into the case using a #2 Phillips screwdriver as a guide.
19. Next up, accumulator pistons are inserted and the springs put in place in preparation to be installed.
20. The valvebody separator plate is modified by Performance Automatic for shift improvement and then thoroughly washed.
21. All valvebody check balls and springs are properly placed per Performance Automatic specifications, then, closely inspected before buttoning up the unit.
22. It’s now when the accumulator piston assembly is installed, taking extra care to be sure the springs and pistons are properly seated.
23. The completed 4L80E valvebody has new shift solenoids and pressure control solenoid. Shift problem issues can often be traced to these solenoids. Before concluding you have transmission failure, check the valvebody and solenoids for proper function.
24. Every Performance Automatic build is dyno tested for proper operation prior to shipment.
25. The Smart Shift from Performance Automatic is a simple solution for precision shift control. You don’t need a laptop or have to be a computer programmer to get results from this controller. Simply wire it up, plug it in and use the switches and dials to set it to your car. In short, the unit is well named.
What Does 4L80E Mean?
4 = Four-Speed
L = Longitudinal application (North/South)
80 = Torque capacity based on gross vehicle weight, where “80” means 8,000 pounds
E = Electronic control
|GM Transmission Weights|
Photography By Jim Smart