Thread: 1st gear slip and bang

2 times in a row now, I leave my car sitting for a week, get back in start the car drive a mile or 2 hit a street light, light goes green, I apply throttle but for maybe a second I don't go anywhere.. then it bangs into gear and I take off... I drive it for 3-4 days after and the issue never re-accurs..
Would a trans go shift kit band aid that issue?

Check your fluid mine did that when it was like half quart low


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Bill and I agree it seems it happens most in impala's even though it's the same trans... The input clutch causes issues like this. Our impala has done it.

https://www.youtube.com/watch?v=RC3w1qmzSE8 Part 1
https://www.youtube.com/watch?v=RqwwYQkOewQ Part 2

So when it revs the car starts moving instantly? I'd get a pressure gauge hooked up like in the video and try.

Yeah..for some odd reason the impala guys complain like crazy abotu this issue. Makes me think their OSID (aka factory tune) has something in it that helps add to the issue.

this tranny has had a overkill tune on it for 4 years now though,
Bill do you think a transgo shift kit would fix/bandaid the issue?

Originally Posted by 1963SS

I can't speak about the 4T65 transmission but on the 4L60's a Transgo and a tune are usually a bad idea. Since the Transgo kit tends to raise the line pressure so does an ECM change. Too much of a good thing is not necessarily a good thing.

Shift kits on 4t65e's actually lower trans pressure as far as I know. Shifts get faster due to the springs being stiffer (not directly related to pressure, just modifies the cushion on the apply lines), and the computer recognizes it's shifting faster and will then adapt using pressure.