8L90 upgrades?

AJMBLAZER · August 25

113,****** miles on my truck. Transmission shifts okay. Had the GM service update done with Mobil fluid at about 30,000 miles. Looking to do a pan and filter fluid change this fall and considering some upgrades. Has anyone else done things such as a shift kit, deeper pan, or the transmission cooler bypass valve?

What did you do? Which brands did you use?

CamGTP · August 26

I don't know of any actual shift kits anymore because everything is controlled by the computer now. There are fix it kits for the valve body to correct known issues with the 8 speed but not actual shift kits of the old days with Th350's, or 4L60 and 4L80e transmissions.

If the transmission runs hotter, I believe they still have a thermostat on the cooler lines of those trucks. You can mod the thermostat to always be open to reduce the fluid temps. I do that on all the 6 speed trucks to reduce the fluid temps by 40 degrees or more. A deeper pan isn't really required.

If you really want it to shift faster or better you have to tune it. But tuning a 2019+ truck is insanely expensive to do and not really worth it if my opinion. Plus you need have a tuner that really knows these new computers well, I wouldn't trust just anyone.

Gangly · August 26

You can replace the Thermal Bypass Valve (TBV) and that helps tremendously with keeping the transmission temps down. A key to a long transmission life is proper fluids, and proper fluid temperatures. If you want to keep your transmission going for the long haul and haven't replaced the thermal bypass valve, I would suggest it.

AJMBLAZER · August 26

I've got one of the Superior bypass valves on the list of upgrades. Hearing not to bother with a deeper pan. I might just add a drain plug to the factory pan and call it good.

I guess shift kits were the wrong word. Looking at the Sonnax upgrades to make things work a bit better/more original.