94 Trans shift 1-2 harsh after warm-up

[Mitch1994Blazer]

I have 70k on my 1994 Tahoe ( actually still called a full size Blazer that year ) and it shifts smoothly through all 4 gears until I am fully at operating temperature, then my 1-2 shift become quite harsh, with the 2-3 shift very firm.

I also seem to be getting a little whine in First gear.

Is there some sensor that I should check, or is my transmission failing?

I've done several fluid changes, using Castrol High Mileage fluid. It has helped, but I still have the condition.

Thanks for any suggestions!

Paul...

 

[lesterl]

Could be valve body wear.....

 

[Jounier11]

you could use lucas tranny aditive next 30k when you do that tune up on the tranny but really it does sound like that tranny is ready for a rebuild a complete one probably 2k or 3k if its a 4x4 at a professional shop.