New for 2001 is the 4L60-E HD, a heavy-duty version of the 4L60-E designed to withstand the higher torque loads of GM's LQ4 6.0-liter gas engine in the GMC Denali. The 4L60-HD features a host of more robust parts that provide increased strength, which allows owners of these luxury sport utilities to enjoy excellent powertrain performance at a reduced overall vehicle weight.
NEW OR CHANGED FOR 2001 MODEL YEAR
· Light-Weight Transmission Case for C5 Corvette
· LS1 Opel Omega Application
· Strengthened Input and Reaction Gearsets with 5-Pinion, Powder Metal Carriers
· Heat-Treated Stator Shaft Splines
· Aluminum Stator Shaft Bushing
· Induction-Hardened Turbine Shaft
· Heavy-Duty Low/Reverse Roller Clutch
· Additional Friction Plate in the 3-4 Clutch
· Improved Input Carrier and Reaction Shell Thrust Bearings
· Shot-Peened Output Shaft
· Revised Valve Body Calibration
4L60-E HD STRENGTHENED INPUT AND REACTION GEARSETS WITH 5-PINION, POWDER METAL CARRIERS (4L60-E HD)
The input and reaction gearsets are each composed of a sun gear, pinion (or "planetary") gears and a ring gear. Both gearsets now use five pinion gears instead of four. The additional pinion gear spreads torque loads around to reduce the load supported by any one gear, in both compression and bending. Together with this change is a switch to higher-quality bronze batwing washers, which ride under each pinion gear and serve as a bearing surface.
Additionally, the pinion gear carrier in each gearset is now made with powder metal. Powder metal parts are formed by pouring a fine metal powder into a die, which is then subjected to extreme heat and pressure to cause the powder to flow and fuse into a solid material. This process allows for more precise detail on each part, and for more consistent parts and higher strength.
HEAT-TREATED STATOR SHAFT SPLINES (4L60-E HD)
The stator shaft is a fixed, hollow shaft splined to the torque converter stator roller clutch on one end and attached to the pump assembly, which is fixed to the transmission case, on the other end. The splines that mesh with the hub of the stator roller clutch are now heat-treated for added strength. Heat treating involves subjecting a part to a sequence of heating and cooling cycles to relieve internal stresses in the metal in order to attain a desired hardness and strength.
ALUMINUM STATOR SHAFT BUSHINGS (4L60-E HD)
The turbine shaft is the main shaft transferring torque from the torque converter into the transmission. It connects to the torque converter turbine assembly on one end and the overdrive carrier assembly on the other. The shaft rides inside the fixed, hollow stator shaft and is supported by two bushings. These bushings are now made out of aluminum instead of a steel-backed bronze. The aluminum is a superior material that can handle higher loads.
INDUCTION-HARDENED TURBINE SHAFT (4L60-E HD)
The turbine shaft is the main shaft transferring torque from the torque converter into the transmission. It connects to the torque converter turbine assembly on one end and the overdrive carrier assembly on the other. This shaft is now induction hardened for greater strength. Induction hardening is a type of heat treating in which a part is subjected to a sequence of heating and cooling cycles through the application of strong electric current. These heating and cooling cycles relieve internal stresses in the metal in order to attain a desired hardness and strength.
HEAVY-DUTY LOW/REVERSE ROLLER CLUTCH (4L60-E HD)
A roller clutch is a type of one-way clutch with a series of rollers riding in ramps in an outer race. The ramps are shaped such that the rollers can run free in one direction, but are wedged against the outer race if the clutch is rotated in the opposite direction, thereby locking the clutch. The low/reverse roller clutch is activated in the first-gear position and thus sees the highest torque loads. This clutch now has larger diameter rollers to withstand the increased loads.
ADDITIONAL FRICTION PLATE IN THE 3-4 CLUTCH (4L60-E HD)
This clutch now has seven friction plates instead of six, as well as harder core steel in those friction plates. The changes results in higher shift energy capacity.
IMPROVED INPUT CARRIER AND REACTION SHELL THRUST BEARINGS (4L60-E HD)
The input and reaction gearsets have various components, such as sun gears and pinion gear carriers, rotating at different speeds in close proximity to one another. At these interfaces, thrust washers or bearings are used to reduce friction and support any load that may occur between the parts. In the case of the interface between the reaction shaft and the reaction sun gear and shell, a heavy-duty, needle-type thrust bearing is now used in place of a thrust washer in order to withstand increased loads. On the opposite side of the reaction shell, where it rides against the input pinion carrier, the thrust bearing has been upgraded to withstand higher loads.
SHOT-PEENED OUTPUT SHAFT (4L60-E HD)
The output shaft is the final shaft in the flow of power through the transmission. It transfers torque from the output planetary gearset to the drive shaft and on to the rear axle. This shaft is now shot-peened in high-stress areas to increase strength. Shot-peening involves blasting a part with beads of a harder material in order to relieve surface stresses to produce a higher fatigue life.
REVISED VALVE BODY CALIBRATION (4L60-E HD)
As with any new engine application, the calibration of the hydraulic system, such as line pressure and shift timing, has been adjusted to optimize shift feel given the revised engine torque curve. Additionally, the springs in the accumulator valve (a spring-loaded device that absorbs a certain amount of fluid pressure in a circuit to cushion clutch engagement according to engine torque) have been replaced with stronger ones to withstand higher fluid pressure.
CONTINUING FEATURES AND BENEFITS
The 4L60-E and 4L60-E HD use a two-piece transmission case with a 360-degree bell housing that completely encloses the torque converter assembly, instead of traditional three-piece construction with a partial bell housing. The result is a dramatic increase in powertrain stiffness and significantly reduced levels of noise and vibration.
This bell housing is modified to suit the wide range of vehicles the 4L60-E serves in, which includes a large line of trucks as well as the Firebird.
ELECTRONIC CONTROLLED CAPACITY CLUTCH (ECCC)
The 4L60-E and 4L60-E HD use an electronic controlled capacity clutch (used instead of a mechanical lock-up clutch). This clutch uses sophisticated electronics to maintain very small amounts of slip between the pressure plate and the torque converter housing cover. The ability to precisely control continuously variable amounts of slip leads to reduced torque pulses and allows the clutch to be applied at lower vehicle speeds and with smoother engagement. This results in improved drivability and better fuel economy.
ADAPTIVE SHIFT CONTROL
The 4L60-E and 4L60-E HD use sophisticated electronics to modify shift patterns as conditions dictate. The Powertrain Control Module (PCM) monitors factors such as throttle position, vehicle speed, gear range, temperature and engine load. The PCM also measures changes in the operating condition of the vehicle, which occur naturally over time as components wear. Based on these measurements, shift timing and hydraulic line pressure are adapted to maintain optimum shift feel under different conditions - for example, during heavy hauling or trailering. This results in improved drivability and fuel economy. The PCM also allows the system to self-adjust for minor variations in each new unit, ensuring that every customer experiences consistent performance, and ensuring that the transmission will produce a constant high level of performance for the life of the car.
ABUSE AND SHIFT TORQUE MANAGEMENT
When a driver mistakenly subjects a vehicle to an abusive maneuver, such as moving quickly from drive to reverse while rocking the car to get out of a snow drift, abnormal wear can occur. The 4L60-E's PCM helps to protect the powertrain by retarding spark to reduce engine output during such situations. Similarly, the PCM briefly cuts engine torque prior to each shift to reduce driveline lash, thus producing smoother shifts.
A common problem in climbing or descending hills is "shift business," which is the tendency of the transmission to hunt between gears. The PCM addresses this issue by sensing when the vehicle is operating on a grade and selecting and holding an appropriate gear, based on throttle position, engine speed and other factors.
SECOND GEAR START
The second gear start option on the 4L60-E and 4L60-E HD provides an extra measure of security and control in hazardous driving conditions. By moving the gear selector to the D2 position, the driver can reduce engine torque to the drive wheels, increasing control during initial acceleration on slippery roads.
--Steve Ford, Total Integration Engineer, 4L60-E and 4L60-HD.
I'd 'guesstimate' the capacity is 380 foot pounds +/-
Thanks! True to his word, my Dealer coughed up two paperback service manuals the size of Boston Phone Books that I am wading through. Bedtime reading...;>) I have also been clumping around in the annals of GM