I know that I have asked this before.. but.. When my Suburban gets HOT.. on a hot day, my tranny shifts really hard.. I mean it CLUNKS.. on a cold day or even below 70, its fine all day.. but when its 85 and 90, and I drive from LaCrosse to Rochester, by the time I make 52 and get off of 90 , it clunks to down shift and to up shift..
help, opinions, options..
thanks the rat..
Rat
It may not be the Transmission .. those trucks are known to develop some rear differential play due to HIGH MILAGE..
To me that would be the cluck you are hearing.
Does the trans shift smooth thru the gears? most the time you can or make them clunk when the truck is shifting up to or down to second gear.
Try accelerating a little bit harder and see if it still does it., my guess is .. it wont.
If it is determined to be rear diff,change fluid and use synthetic fluid.
My 1996 have the same sound when I purchased 2 years ago and I found it to be rear diff play due to high mileage and swapped out fluid to a synthetic and added a possi-traction additive since I have a possi rearend.Very rarely does it now.
I have never heard of the trannys to clunk, only the transfer case,( chain stretched)and rear diffs.(gear play)
JMHO….Hope this helps some.
I will be in the Rochester area for a few more days.. if you are interested shoot me a pm.. I have been traveling from LaCrosse to Rochester on a daily basis for a few months now..
and you can tell how hot it is by if the truck clunks or not..
I have a GOOD scanner ,we can hook it up and go for a drive and watch it and PM’d you my number 
Late model GM’s with the 4L60E tranny, are known for a 2 to 3, and 3 to 2 clunk. my truck has done it since day one. there is a GM TSB on it. I don’t buy the TSB, but that is what it says, and my tranny hasn’t blown up yet, and i have 160k on it.
Quote:
Document ID# 1430424
2003 Chevrolet Chevy Suburban – 4WD
——————————————————————————–
Information on 2-3 Upshift or 3-2 Downshift Clunk Noise #01-07-30-042B – (Jan 16, 2004)
Information on 2-3 Upshift or 3-2 Downshift Clunk Noise
2004 and Prior Light Duty Trucks
2003-2004 HUMMER H2
with 4L60E or 4L65E Automatic Transmission (RPOs M30, M32)This bulletin is being revised to add the 2004 model year. Please discard Corporate Bulletin Number 01-07-30-042A (Section 07 – Transmission/Transaxle).
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.
Perch,
Thanks for the information…my 2003 silverado has had this problem from the start and often wondered what was wrong… had the truck in for warranty service and the mechanic changed u-joints, checked the trasfer case, and rearend. Still clunks but pulls the boat just fine
I am aware of that TSB on the newer trucks,and I dont agree with them either,but I do believe Rat’s burb is an older model (1990’s)and they were prone to have differential noise due to high mileage and gear wear.
We will see if he gets a hold of me and we check it out 
Quote:
I am aware of that TSB on the newer trucks,and I dont agree with them either,but I do believe Rat’s burb is an older model (1990’s)and they were prone to have differential noise due to high mileage and gear wear.
We will see if he gets a hold of me and we check it out
yeah, he never said what year it was, so i just threw that out there, in case his fell into those years.
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