I've searched and found numerous threads about different clunks but not what I'm experiencing. The only time I hear/feel a clunk is when I start up a long hill and the truck shifts back down into 4th there is a violent clunk from just under my feet. That's it. I'm thinking either a U-joint or the connection between the driveshaft and transmission must be the problem. Anyone else experience this or know the problem?

Thanks

 

Wow!! Either no one has any ideas or the news is so bad nobody wants to be the one to shatter my world

 

Does it clunk when it goes into 4th from third every time or only after its had a big load on it aka going up a grade and when you are back onto level road? I know of them clunking and banging when shifting down into 3rd when you're going 80+mph but not going back into forth. Sometimes my truck over revs a bit when it shifts down a gear, probably just confusing the ECU with the throttle though.

 

If it's DOWNSHIFTING from 4th to 2nd, it's gonna bang and clunk. Before accelerating up a hill, hit the OD button.

 

I can be driving along at 40 in town or 75 on the interstate. When I get to a steep grade and the trans initially downshifts to take the grade there is a hard clunk that you both hear and feel. It's not normal and hasn't always been there. This does not happen at any other time. It feels as though there is momentary slack in system and suddenly regains it.