PROJECT LML

some performance tuning and a cold-air intake. While we don’t really abuse all that power by doing boosted four-wheel-drive launches and burnouts around town every day, the stock Allison transmission is not going to be real happy at 900+ lb-ft of torque for long when you do get after the throttle on occasion. The Allison 1000 transmission has been a home run for GM backing these Duramax powerplants since they were released in 2001. They work great for daily driving and are incredible for towing, but obviously they were designed to handle stock power levels. Increasing engine output by 130 hp and 200 lb-ft of torque, you’ve almost got to expect something to give eventually. At some point we’ll go through and do a full build on this transmission with better clutches, an improved valve body and a big triple-disc torque converter, but for the time being that’s a big expense we’d like to put off a little longer. With that in mind, we’ll try and take care of this stocker by behaving the best we can and keeping the tuning down in a lower power level. There are a couple inexpensive ways we can improve the transmission and help extend its life cycle, however.

The EPC Solenoid. What is it and what does it do? EPC is short for Electronic Pressure Control and that solenoid does exactly what it states. Located within the transmission’s valve body, the EPC Solenoid controls the fluid’s line pressure, which will be how much pressure is applied to the clutch packs while cruising, accelerating and shifting through gears. The 2011-16 LML was set up to run at 80 psi of line pressure, and the EPC will spike pressure up to 250 psi during a shift. Once the shift is complete, pressure drops back down to that 80 psi until another shift occurs. Anyone with a knowledge of how the automatic transmission works would understand this, but in simple terms, increasing the line pressure on the clutches would put more force on the clutch faces and reducing the chance for slippage, which creates heat and will lead to premature failure.

 With the new external filter installed back onto the transmission, it was time to remove all the bolts and drop the fluid pan to gain access to the internal filter and valve body. This can be a pretty messy job, so be prepared with a large drip pan....

 With the old internal filter removed and properly discarded, you get a direct view of the transmission valve body. All these parts and solenoids are what tell the transmission what gear to be in and when to shift. In an aftermarket upgraded...

 While we aren’t quite ready to do a full build on this Allison, 496 rear-wheel horsepower with the Edge Evolution’s biggest performance setting tells us anything we can do to help the stock transmission live and hold a little longer will be...

 There is one key step required when changing the external transmission filter. Don’t forget to transfer the round magnet inside the top of the filter to the new filter before spinning it on. That magnet is important to keep in the transmission as it...