Quick shift

[Tweek]

My tranny in my 80- Vette seems to shift very quickly from 1st tru 3rd, even when I give it a foot full. It also doesn't downshift quite like I think it should, it will kick down if full trottle it but seems to lag any other time, any ideas?

Ron

 

[cntrhub]

First things first. Get the engine and trans nice and hot. Meaning, take a nice 10/15 minute ride. Now check the Trans fluid level. Engine running. Trans in park. Pull the stick out and clean it off. Install stick and send it all the way home in it's housing. Wait literally 2 seconds. Pull the dip stick and read the level. Keep the tip down, so the fluid does not walk up the stick and give you a false reading. Where is the fluid level?
What color is the fluid? Does it smell burned or look black? A brown red or crimson color is normal.
Check the vacuum moduator or the vacuum hose from the modulator to the carb. Check for cracks or leaks from the hose's ends. Remove the hose from the carb and modulaor fitting. Place a vacuum tool to the hose assmebly. Will the hose's integrity keep vacuum?

 

[69MyWay]

My guess is a bad vacuum modulator, and or bad vacuum line.