Why does my '97 Chevy Silverado transmission shift hard when it gets hot?

[Rob]

I recently dropped the pan and replaced the fluid and filter. I think it's a 460LE transmission. It mainly shifts hard after a long highway run at near constant speeds. Any suggestions? Thanks!

 

[george 2]

see if you need to add more transmission fluid

 

[Gene B]

sounds like cooler line stopped up to a certain degree. if fluid does not get cooled down enough will be too thin to work properly.

 

[ttompetty]

CHECK THE FLUID LEVEL WHILE THE VEHICLE IS IDLING,, DOES THE FLUID SEEM BROWN OR SMELL BURNED.. WHEN U REPLACED THE FILTER ARE U ABSOLUTELY POITIVE YOU HAVE THE FILTER ON THERE TIGHT, DID U REPLACE THE O-RING OR RUBBER THAT COMES WITH THE NEW FILTER IF IT DID,, IF NOT OR YOUR IN DOUBT YOU MAY HAVE A SLIGHT LEAK AS THE FILTER IS TRYING TO DRAW FLUID UP,,,ART.. ALSO,, IM SURE U DID CHECK THAT U HAVE THE CORRECT TRANS FLUID....

 

[Mac]

Might be the temperature sensor/switch.