Tranny Issues HELP

[Phat300]

We took our ruck (05) on short trip and when we got out on the highway the transmission seemed different. It was as if the torque converter wasn't locking up in high gear. RPMs were about 2200 at 60mph...just seemed as if it needed to another gear. When we stopped to check tranny fluid etc. (all was fine) I noticed that at 10mph if I took my foot off the gas then tapped it we heard a fairly loud "clunk" as if the front U Joint or torque converter had problems.......needless to say we took it to the dealer who said everything was acting just "fine".......

Any ideas on what was up? Obviously if I pick it up (this week) and it is still acting like this I'll put the mechanic in the truck with me........

[C1Trob]

My automatic seems to set me up at around 1900-2100 rpm @ 70MPH. Overdrive, or (4th) is on at that setting.

[Mike in AZ]

Sounds like it's not shifting into overdrive.

Torque converter lockup happens above 40mph after a few seconds with no throttle activity. This is in either 3rd or overdrive. Take it out and use it in "3" and sneak up on 45 mph. You should feel the tq converter lockup and see a 100 to 200 rpm drop. After you get that, shift to "D" and see if it shifts to overdrive. I'll bet it doesn't.

Mike

[JimGnitecki]

The numbers don't tally.

You are apparently seeing 2200 rpm at 60 mph?

With the stock 3.73 rear axle,

RPM at 60 mph in overdrive and lockup = 1798
RPM at 60 mph in 3rd with lockup = 2568

I suppose it might potentially be possible to see 2200 in overdrive withOUT lockup having occurred, but I would think that would have to be under some notable load (gradient or STRONG headwind) to be THAT high.

The "clunk" at 10 mph on application of WOT is also NOT normal.

Something is amiss, and if one Chevy dealer doesn't think so, I'd go to a smarter one.

Jim G