4l60e 3-2, 2-3 Hard Shifting

[silverad03]

I have an 03 Z71 and the last couple or three weeks the transmission has been down-shifting violently from third to second gear, and I can also feel it when it upshifts from second back into third when I get up to speed.

 

I notice this condition most when I'm on residential streets and I have to slow down for a car in front of me turning, or when I slow down to turn off a major street onto a side street. I'll give it some gas to resume speed and the truck doesn't really respond at all for a full second or more, wait for it, wait for it...BAM!! the transmission downshifts into second very violently, there's a very loud CLUNK and you can feel the transmission buck, and the truck takes off like it just got goosed in the back end. Of course it only needed second gear just to get some momentum going again and then it shifts right back up into third a few seconds later with a solid clunk again and a slight jerk in the power delivery. I'm not driving it like Mario Andretti so that is not the case (although the transmission doesn't buck when I anticipate with a 3/4 throttle because the transmission shifts faster). I've tried driving like an old man with a feather on the pedal when it's time to resume speed and sometimes it helps, often it doesn't.

 

I travel to work almost exclusively on city streets that wind through residential neighborhoods so I'm in the 2-3 gear range a lot. Not only is this very annoying, I'm starting to be concerned about drivability in the winter because it shifts so violently it could potentially cause a loss of control on a slick street.

 

First of all, what could be causing this issue? I think it has to change from the 1-2 clutch band to the 3-4 clutch band, which has always caused a clunking condition, but why is it not shifting right away and then bucking? Possibly the 3-4 solenoid is sticking?

 

Second of all, is there a TSB out there for a PCM update related to shifting? Not only does it needs to shift softer, but I think there wouldn't be nearly as much clunking going on in the first place if the shift wasn't so slow that most of the driveline backlashes and then slaps forward again when it moves from the 1-2 solenoid to the 3-4 solenoid.

 

BTW, I already have the nickel plated slip yoke.

 

Ok, I'll stop typing, what you guys think?

[silverad03]

Well, after posting this topic, I found another topic that addresses the normal clunk issue. What that thread does not address is why the shifting elevated from a livable clunk to a violent, bucking clunk.

 

I'm going to check my transfer case fluid when I get home - maybe my case has sprung the inevitable leak and I haven't noticed it yet.