What is the Clunk?

[gschretter]

Axle Housing Flex.

Jeeps with high hp (400) have the same problems.

The axle flexes causing the yoke to slip a little

Your u-joints bolts (stock) flex.

When you slow down everything is flexing back.

Why does low HP not do it.
Simple they cause less stress and take longer to build the flex.

Switch over over to all Tom Woods drive shaft and u-joints and YOKES!!!
Everything will go away. Of course it will cost about $3,000.00

What you have done is stretch out everything and have stress the steel.

On my chevy my yokes come with straps. I have not seen straps since 81 Jeeps. If you have straps that is the best place to start.

I can do a 1/2 mile burn out in my jeep in 4x4. The first time I did it I broke all 4 yokes and the bolts all broke from the straps. I replace with u-bolt and heavy duty yokes and not have one problem..

I hope I helped a little.

I am learning about these new chevys but suspension I know inside out.

[airtight_python]

Good deal. That sounds resonable but I think the problem will just have to stay there until something major breaks. Thanks for the input everyone.

[skipr]

Originally Posted by LT-Z71drvr

Texas-
The noise is different, but I think the two problems are related.
Like when you shift from D to R, or vice versa.
I think that there is just that much play in the driveline.
It would seem to me that over time it would wear something
out...
I guess we'll see...
Might hafta go get a Ford!!!
LOL!!

I am sure you are right. It's driveline the ring and pinion bashlash, the best way to tell is drop the driveshaft at the pinion yoke and twist the yoke back and fourth yo may get as much as an inch of play, if so don't listen to GM open that cover plate and check wear on ring gear teeth, and the differential pinion shaft (not the pinion gear) if pinion shaft is sloppy you can expect a differential snap in future. And beleive me it's not a pretty sight.Oh and going to Ford is not the anwser, You think those trucks are trouble free?

[Bigbluechevy]

I have a 2004 Crew Cab 5.3L and I here a clunk when the automatic transmission changes from 2nd to 3rd gear. Is this normal, or a manufacturing defect? If anyone has the Technical Service bulletin for it, could you please post a link or cut and paste it in here? Thanks.

[superboog]

I had the same problem with my 2000 Z71 4WD soon after I bought it from the dealership. It was used with 48k and a dealer installed 6" lift. I took it back to them with an extended warranty and they were reluctent to asume responsibility for the problem until I mentioned the fact that thousands of trucks have lifts and this particular dealer wouldn't warrantie there own lift kit. Anyway they did fix the clunk to the tune of $2,700. They said it was the yoke and some shims that have to do with the transmision and transfer case.

[rhansme]

2001 Chev Z71 4WD and I had the "clunk" from day one. They greased it at first, but it did not last long. Then I got the nickle slip yoke installed. I now have over 55K miles on it and still no loud clunking like before the nickle slip yoke was installed!

[Sonny01]

I had the clunk and changed the transfer case fluid out for the new improved stuff and the clunk instantly went away.

[budone]

Originally Posted by vnotaro

I've experienced the same clunk about 50% of the time since the truck was new (2001). GM has put out at least one TSB on this but I don't know the number.

TSB 05-07-30-012

[travis712]

Dads.. 2003 1500 4.8 4x4. Has the clunk. We bought it used at around 60,000 miles. Always has done it, don't know if it does it in 4x4 but in 4x2(99% of the time) it always does it. I think it does it between 1st and 2nd though. I'll see later.

[yakk]

my 04 Z71 ext cab clunks between 1st & 2nd, usually at low speeds.

[travis712]

^same, dads is a ext cab too.

[twomorestrokes]

Just like the piston slap noise: Normal.

"This is normal operation. Do not attempt repair. This is from the sum of normal tolerances built into the various driveline components working together".

On a couple of my trucks I used to pull the driveshaft every so often and grease the splines with the special blue GM stuff, but it always came back. I'm happy that this HD doesn't seem to do it. Yet. Maybe the other noises are just drowning it out.

I heard it first on this very forum: Welcome to the Clunkerado Club.

[budone]

Originally Posted by twomorestrokes

Just like the piston slap noise: Normal.

"This is normal operation. Do not attempt repair. This is from the sum of normal tolerances built into the various driveline components working together".

I heard it first on this very forum: Welcome to the Clunkerado Club.

Yeah Piston slap is normal...... I had a 2002 Tahoe that had that.... My goodness, those whpo never heard it swore I let the oil run dry!!!!

[Rammer500]

Sounds like we are talking about 2 different clunks. One is when you accelerate from a stop and the other is when the transmission shifts from 2-3 or 3-2. My 02 Xcab Z71 and my 05 CC z71 both have the shifting clunks. It's most noticeable when you slow down and then accelerate, the transmission shifts from 3rd to second. It's also noticable when lightly accelerating.

Here's the TSB on this one. it's from 04 but I'd bet GM added 05 as well.

A/T - 4L60-E/4L65-E, 2-3/3-2 Shift Clunk Explanation

Bulletin No.: 01-07-30-042B

Date: January 16, 2004

INFORMATION

Subject:
Information on 2-3 Upshift or 3-2 Downshift Clunk Noise

Models:
2004 and Prior Light Duty Trucks
2003-2004 HUMMER H2
with 4L60E or 4L65E Automatic Transmission (RPOs M30, M32)

Supercede:

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


The other clunk is the slip yoke on the driveshaft. I've read the TSB on this one, but I didn't save a copy of it. Dealers lube it and GM also has a nickel plated replacement.

[budone]

Originally Posted by Rammer500

Sounds like we are talking about 2 different clunks. One is when you accelerate from a stop and the other is when the transmission shifts from 2-3 or 3-2. My 02 Xcab Z71 and my 05 CC z71 both have the shifting clunks. It's most noticeable when you slow down and then accelerate, the transmission shifts from 3rd to second. It's also noticable when lightly accelerating.

Here's the TSB on this one. it's from 04 but I'd bet GM added 05 as well.

A/T - 4L60-E/4L65-E, 2-3/3-2 Shift Clunk Explanation

Bulletin No.: 01-07-30-042B

Date: January 16, 2004

INFORMATION

Subject:
Information on 2-3 Upshift or 3-2 Downshift Clunk Noise

Models:
2004 and Prior Light Duty Trucks
2003-2004 HUMMER H2
with 4L60E or 4L65E Automatic Transmission (RPOs M30, M32)

Supercede:

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


The other clunk is the slip yoke on the driveshaft. I've read the TSB on this one, but I didn't save a copy of it. Dealers lube it and GM also has a nickel plated replacement.

Yes, 2005 was added. I stated earlier there are other TSB's concerning the Silverados and Sierra's.