Shift Slam

'98 Chevy Z71, 5.7 with auto trans... bought it new and now have 76K miles... all 3 of the incidents have occurred after driving on the interstate for several hours, usually after long trips towing my bass boat.
When I exit off and come to a stop everything seems fine. It's when I go to take off again the transmission slams into each gear as if there are no clutches, bam, bam, bam, in each gear and it will not shift into overdrive. Yesterday was the 3th time this has happened since I bought this truck... I've learned to "fix" the problem by stopping, turning off the engine and restarting it.. alls fine again..
Anyone have an idea of what it might be? Could it be the torque converter not disengaging after slowing down and stopping? My guess is the computer just farted and needs to be reset by turning it off and on again...
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
My '99 Yukon does that, it goes into tow mode and firms up the shifts automatically. It will do that if you lead foot it repeatedly ala 18 yr old race boy. (don't ask we all have our moments) That's why the newer trucks have a tow / haul switch now.
--
John
"anything you say can & will be misquoted & used against you"
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Thanks for the input.. but '98's and earlier models didn't have the tow mode as an option, at least mine didn't... I've experienced the tow mode your talking about in another truck my buddy had and this is "something like" that but when I say it shifts hard, this shifts hard. It shifts with NO transition, just from one gear to another... By the way I've done 2 filter and fluid changes, 1st @ 30K and 2nd @ 60K... pan was as clean as a baby's behind both times. This has got me guessing as to what really happened.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Does even letting up on the gas cause the HARD shift? I notice with my truck that there are occasional times wherre it will shift harder than normal, mostly from 1st to 2nd gear, but if I feather the throttle just before the shift you can hardly feel the shift between gears.

----------------------------------------------------- users trucks from this group listed below ----------------------------------------------------- http://users.eastlink.ca/~mikemcneil/index.htm
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
No, it doesn't seem to be related to the gas pressure or not when it's in this mode. It makes no difference what I do, easy on the gas or not when it's ready to shift, it shifts.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
My 1997 K1500 did the same thing at 55000. The dealership had to replace the valve body in transmission.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here. All logos and trade names are the property of their respective owners.