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8L90 upgrades?

AJMBLAZER
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AJMBLAZER Enthusiast

AJMBLAZER

Posted
Posted

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 Senior Enthusiast

CamGTP

Posted
Posted

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 Senior Enthusiast

Gangly

Posted
Posted

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 Enthusiast

AJMBLAZER

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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.

  • 9 months later...
ebarden83 New Member

ebarden83

Posted
Posted

The revised stator plate might be nice so you don’t get the cold start 1-2 jarring shifts. My tranny shop also recommended me a different brand torque converter. I’m only at 75k so I don’t know yet what I’ll do. 

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