Test drove 04 Z71, clunk from 2nd to 3rd

jjrobo · April 27, 2006

I test drove a 2004 Ex. Cab Z71 this morning. When It got warmed up and I took off really slow, it seemed to clunk when shifting from 2nd to 3rd. I drove two others just like it and they seemed to shift the same, but without the audible clunk. I also thought that it shifted a little harder than the rest that I drove, but that could have been my mind playing with me since I could hear something. It only has 22,000 miles on it.

Is this something normal, or something that I should stay away from?

Thanks,

Jeff

ChevyTech007 · April 27, 2006

Subject: Information on 2-3 Upshift or 3-2 Downshift Clunk Noise #01-07-30-042C - (09/27/2005)

Models: 2006 and Prior Light Duty Trucks

2003-2006 HUMMER H2

2006 HUMMER H3

2005-2006 Saab 9-7X

with 4L60-E or 4L65-E Automatic Transmission (RPOs M30, M32)

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This bulletin is being revised to add additional model years and information pertaining to the 2005 model year vehicles . Please discard Corporate Bulletin Number 01-07-30-042B (Section 07 - Transmission/Transaxle).

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Important: For 2005 model year vehicles, refer to Corporate Bulletin 05-07-30-012 or newer.

Some vehicles may exhibit a clunk noise that can be heard on a 2-3 upshift or a 3-2 downshift.

During a 2-3 upshift, the 2-4 band is released and the 3-4 clutch is applied. The timing of this shift can cause a momentary torque reversal of the output shaft that results in a clunk noise. This same torque reversal can also occur on a 3-2 downshift when the 3-4 clutch is released and the 2-4 band applied. This condition may be worse on a 4-wheel drive vehicle due to the additional tolerances in the transfer case.

This is a normal condition. No repairs should be attempted.

pm26 · April 28, 2006

Now, that is very comforting. This basically says: folks, that is the way it is, if you don't like it, go piss up the rope.

I have hard time believing that any serious manufacturer would design a modern truck with a loud clunk when shifting. Unfortunately, Chevy is not the only truck that exhibits this behavior. If you want to experience a real clunker, go test drive a new 3/4 ton Dodge truck with a heavy duty 4 speed automatic transmission.

jjrobo · April 28, 2006

It has me a little worried. Almost all the GM trucks that I've test drove w/ 20 -25k miles on them feel like that. Only the one that I really want makes a noise as well. I don't know what to do.

Should I just not worry about it, or keep searching?

silverad03 · April 28, 2006

It has me a little worried. Almost all the GM trucks that I've test drove w/ 20 -25k miles on them feel like that. Only the one that I really want makes a noise as well. I don't know what to do.

Should I just not worry about it, or keep searching?

<{POST_SNAPBACK}>

Well from what I've heard it seems like almost all of the late model light duty auto trannys/transfer cases exhibit the clunk. I've driven a few automatic transmission vehicles and my 03 Silverado 1500 is my first vehicle with an electronically controlled transmission and it is a different beast than the old vacuum controlled trannys. It has taken me a long time to get used to the way this tranny is going to act, partially because it's a moving target with the system adapting all the time - I don't drive the same way constantly, sometimes I drive hard and sometimes I drive my truck easy and the tranny doesn't know what to do when I change the way I drive - which usually results in an overly harsh/sloppy shift and an accompanying clunk in the transfer case.

What I'm trying to say is that GM (and other auto manufacturers) seems to have tried to take something simple that worked and make it overly-complex - and in doing so, they have thought themselves into a corner and can't seem to figure out how to time a transmission shift quick enough so you don't get backlash...

Because of this, GM calls the sloppy shifting 'normal' so they don't have to spend any money to deal with it.

However, that being said, there are a ton of these trucks out there with the clunk and they are still running strong - just ask any of the guys around here, as many of them have well over 100k miles on their trucks.

ChevyTech007 · April 28, 2006

Its just the sound of the trans doing its business. I do not believe it will cause any premature failure. Let's not forget that it is a truck that is meant to be used for work and pulling. If you want a caddy ride, buy a caddy

cdmm151 · April 30, 2006

This is bull. I have both 2005 4x4 crewcab and a 2005 4x4 suburban. Both are 1/2 tons. The only difference in the drive train is the crewcab has an aliuminum driveshaft. Everythingelse is the same and the suburban has a smooth shift without any noise what so ever. I am going to the dealer in about a week and I am going to have him look into this mattter further.