have a ??? for you NNBS owners

[lechez71]

I'm looking into getting a 2007 silverado nnbs. i test drove a truck that i really like and hopfully the deal will come thru. when i drove the truck i noticed a clunk or pop noise when you come to a stop or take off. It's kinda hard to explain but guessing it could be a differential, suspension, or the slip yoke in the tranny binding up, but i have no clue so asking if any of you have this problem, or heard of this? its 2wd if it helps any. I have a buddy with same clunk noise in his truck and he bought his new hasent given him problems but dont feel or sound right but could just be me.

[1slo4.8]

No clunk noise here

[pl4yboy]

None here either.

[jansen]

Probably a u joint.

[GraniteBlueNNBS]

I get that noise in mine some times, I would not worry myself... mine is a 5.3 with the 6 speed.

[BrutalSierra]

is it an excab? Maybe its the carrier bearing.......

[Ray@NP]

pull the drive shaft and lube the slip yoke splines

[Slow08]

no noises here

[conekiller01]

Pretty sure there is a TSB on the slip yoke splines drying out need to be greased like ray said I once saw a write up for installing a grease zerk in it dont recall where though ....

[bartjo06]

Pretty sure there is a TSB on the slip yoke splines drying out need to be greased like ray said I once saw a write up for installing a grease zerk in it dont recall where though ....

Here you go:

#09-04-21-003A: Clunk Noise at Stop or From Launch (Clean/Lubricate Rear Propshaft Slip Yoke Splines) - (Jul 8, 2009)


Subject: Clunk Noise at Stop or from Launch (Clean/Lubricate Rear Propshaft Slip Yoke Splines)


Models: 2007-2009 Chevrolet Avalanche, Silverado, Suburban, Tahoe 1500 Series

2007-2009 GMC Sierra, Yukon, Yukon XL 1500 Series

All Equipped with 4WD



Attention: This bulletin contains a procedure to clean/lubricate the rear propshaft slip yoke splines and replace, if necessary. Check the history on this vehicle. If the lubrication procedure has been performed previously, then continue on and replace the transfer case rear output shaft.


Condition
Some customers may comment on a bump feel or clunk noise at a stop or on launch. Customers may also comment that the bump feel or clunk is noticed after the vehicle has come to a complete stop and that it feels as if the vehicle was bumped from behind.

Cause
This condition may be caused by a slip/stick condition between the rear propshaft slip yoke and the transfer case rear output shaft splines. Braking to a complete stop can force the propshaft slip yoke forward into the transfer case while the vehicle rebounds slightly backward after stopping its momentum.

Correction
Note: The clunk noise may also be due to fuel movement in the fuel tank when not completely full. If the condition is eliminated after filling the fuel tank, the noise is isolated to the fuel movement in the tank. Please make no repair attempts, as this noise is considered an operating characteristic.

Clean/Lubricate Rear PropShaft Slip Yoke Splines
Remove the rear drive shaft. Refer to One-Piece Propeller Shaft Replacement in SI.
Inspect the rear propshaft slip yoke splines.
Note: Protect the transfer case rear seal from Brake Clean.

Clean the rear propshaft slip yoke splines with Brake Clean or equivalent and a shop towel.
Assure that the splines are free of rust or other foreign material.
Lubricate the spline with Automatic Transmission Fluid, P/N 88861003 (in Canada, 88861004).
Reinstall the rear drive shaft. Refer to One-Piece Propeller Shaft Replacement in SI.
Road test the vehicle and verify that the noise is gone.
If the vehicle has a repeat concern after lubricating the slip yoke splines, replace the rear output shaft.
Replace Transfer Case Rear Output Shaft
Note: Do Not replace the output shaft unless the cleaning and lubrication procedure is ineffective.

Remove the transfer case assembly. Refer to Transfer Case Assembly Replacement in SI.
Disassemble the transfer case. Refer to Transfer Case Disassemble in SI.
Replace the transfer case rear output shaft. Refer to the Parts Information below.
Assemble the transfer case.
Reinstall the transfer case assembly.