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Topic
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Hello experts.
I have a 2004 Avalanche Z71 with 5.3L. It has 123K on it and over time it has established a clunk between 2nd & 3rd Gear. I am 58 years old. I bought the truck new and me and this truck are going the distance together.
I replaced the trans, transfer case with GM rebuild units (no third Party) and also all new U-joints.
IT still has clunk at low speeds between2-3 gear. Sometimes louder than others.
Under acceleration and more pressure the trans shifts without clunk. It is only at low speed (very little acceleration or pressure) that the clunk is their.
I have given up on the local mechanics which say it is inherent. It is not, This clunk came over time and I want it gone.
I like road trips and I don’t want to take her out until this is resolved.
Any suggestions
thank you
Daniel Helme
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Replies
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Gmule:
Thank you for responding. Yes, the rear has been inspected and gauged accordingly.
I looked on old blogs from 2004-2009 and others have had this issue with no resolve.
I am wondering if the converter can have anything to do with this.
As the car warms up and is driven the clunk between 2nd & 3rd at low speed is more consistent.Note that it doesn’t occur every time. It is primarily intermittent
13aceofspades13
Thank you for your respnse.
It does not jerk, it is just a clunk between 2nd & 3rd
Please read my response to GMule.13aceofspades13:
sorry, I didn’t answer part of your question.
It does not shift hard or jump. It actually feels sloppy, like one gear (2nd) releases then it takes a second for 3rd gear to engage and when it does it clunks.
Note that this clunk can be very loud at times. It can be heard if you were walking on the sidewalk.Dan
This is more common with the clunk on take off issue, but take a look at your rear springs.You should have round plastic pads attached to the top of the overload spring at the ends. What can happen is the pads come lose and when the rear end torques the springs slap causing a loud clunk. Like I said its more common at takeoff but its worth looking into.
Sloppy shifting in the 4l60e can be helped greatly with replacing the plastic accumulator for a metal one and installing a corvette 4th band apply servo. Both are not to hard to do and an absolute must for towing with the 4l60e.
Bsosborne1
Thank you for your response. I will let you know on the pads. Im starting to think of the solenoids also.
what do you think.
The trans is new GM rebuilt (2 months ago) and I’m not sure if they replaced the solenoids but, 2 times now it did not downshift to 1st gear at red light. When I started it was in second then downshifted.What do you think, can this be a multiple issue with converter and solenoid combined issue.
At only two months old, I would be looking to get that trans warrantied. If these problems are just starting then it could be the trans. It could be the solenoids, you could have a stuck valve, you might have debris in a bore….It could be lots of things. If its a new unit…None of that is your problem. Have the parts dealer deal with it.
As for GM transmissions….GM built an inadequate transmission for that truck from the get go. The is a long and storied past with the 4l60E in trucks. GM has lost plenty of money in warranty work on these trucks due to constantly failing transmission. Some are good, most are not. I would not use a GM unit. Their are lots of great transmission re builders out there who have come up with solutions to the 4l60e’s problems. If I was looking for a 60E I would use one of those guys. 4l60e’s were ok in s10s and cars. Not in 6000lbs trucks.
Now let me say that I own a z71 that has a 4l60e with 225,000 miles on it. I’ve made it last that long by fixing the problems before they happen and babying it. I also only run Amsoil ATF and flush it at the change intervals. So it can work if you get a good one.
Bsosborne1
The 2nd -3rd shift clunk was in the original trans also. This is why I dont think it is in the transmission its self. Their is something else going on that no-one seems to be able to identify.
Thank you
DanWell it was worth a look.
Was your old transmission not down shifting also?
Do you know the clunk is coming from the trans and not the driveshaft or rear end?
Do you have the electric locking rear differential?
Are you running an aftermarket tune or performance chip?
Have you inspected the transmission cross member mount for damage to the rubber isolator?
Bsosborne1
Yes, I am using super chips but it did no good, so I’m back at factory settings.
The one thing I do notice, when i put it in tow mode the clunk is much less in intermittent’s and loudness.
This is another reason I am thinking Solenoids or converter.
I am bringing to another shop next week. I am in south Florida and their are many wannabe mechanics so, it gets expensive for their guessing.Dan
Two of the things that tow/haul mode does is change the shift pattern and raise the internal line pressure.
Both of those should relate to the transmission so it shouldn’t carry over to a new unit…unless its a cooler line blockage or a blockage in either the radiator cooler or if equipped the auxiliary cooler.
If your taking it to a trans shop talk to them about putting in the corvette servo. That will raise the pressures and firm up the shifts…both good things for the 4l60E. I know of no draw backs to going with it.
Did you get a new torque converter with the rebuilt trans?
2004 Chevy Truck Avalanche 1500 4WD V8-5.3L VIN T
Vehicle » Technical Service Bulletins » All Technical Service Bulletins » A/T – 2-3 or 3-2 Shift Clunk Noise Information
•A/T – 2-3 or 3-2 Shift Clunk Noise Information
# 01-07-30-042H: Information on 2-3 Upshift or 3-2 Downshift Clunk Noise – (Jan 14, 2014)
Subject: Information on 2-3 Upshift or 3-2 Downshift Clunk Noise
Models: 2014 and Prior GM Passenger Cars and Light Duty TrucksEquipped with 4L60-E, 4L65-E or 4L70-E Automatic
Transmission (RPOs M30, M32, M70)This bulletin has been revised to add the 2013-2014 model years. Please discard Corporate Bulletin Number 01-07-30-042G.
Important :
For 2005 model year fullsize utilities and pickups, refer to Corporate Bulletin Number 05-07-30-012.
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 more pronounced 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.
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