Greasing NNBS (2008) Silverado intermediate steering shaft.

[Mossyoakglock]

In the never-ending battle to find my front end clunk, I came across the GMT-800 issues of the intermediate steering shaft clunk. I figured I'd give that a shot since it's something I can do relatively quick and easy. 

This was the official TSB and procedure from GM:

https://www.4x4us.net/documents/2010-10-04_231157_intermed_shaft_lube.pdf

In some other reading, people just used a grease gun and stuck the hose into the steering shaft since that grease kit has not been available for a while now. I'm sure this is not my issue but going to give it a try. Has anybody greased their NNBS steering shaft and how did you go about it?

I plan on using some Moly grease I already have in my gun since it's pretty tacky.

[newdude]

Upper intermediate shaft issues are not all that common on GMT-900s.

 

Most common are the lower intermediate shaft and the u-joint on it, the steering gear mounting bushings and the sway bar to frame mounts breaking.  

 

Have you checked either of those 3?  

[Mossyoakglock]

I replaced the sway bar bushings along with the end-links. I did check the lower shaft and didn't find any play in it. I also checked the bolts and everything on the steering gear and didn't notice anything. 

 

I'll check the lower steering shaft again. My thought on it maybe being the intermediate shaft was after reading about the GMT800's and a possible knocking. I had read that some people with '08s were having the issue. Maybe some where using the old ISS from the previous platform. For $50 I can replace it so not too much lost if it doesn't work.  

 

It only happens when going straight and over a small bump in the road. Doesn't happen when turning or anything. 

Edited December 15, 2021 by Mossyoakglock
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[Supreme Pizza]

Before replacing any more parts - You could always start with the free stuff. Les Schwab will do a free shakedown and road test. Then they give you a written estimate that pinpoints what they think needs to be done. At that point, you can evaluate their suggestions to determine if its correct. Then you just have to decide if you want to fix it, or let them do it. Those guys evaluate these rigs all day long, so they have a lot of experience inspecting them.

 

Just an idea. Might not be a good idea, but oh well.

[rbdjr]

10 hours ago, Mossyoakglock said:

In the never-ending battle to find my front end clunk, I came across the GMT-800 issues of the intermediate steering shaft clunk. I figured I'd give that a shot since it's something I can do relatively quick and easy. 

This was the official TSB and procedure from GM:

https://www.4x4us.net/documents/2010-10-04_231157_intermed_shaft_lube.pdf

In some other reading, people just used a grease gun and stuck the hose into the steering shaft since that grease kit has not been available for a while now. I'm sure this is not my issue but going to give it a try. Has anybody greased their NNBS steering shaft and how did you go about it?

I plan on using some Moly grease I already have in my gun since it's pretty tacky.

That is a older service bullitin, they replaced that bullitin with a updated shaft now, also check the bearing/plastic bushing on the bottom of the colum, somtimes that plastic bushing wears out also, You can take the steering shaft off the truck and yes work some moly EP grease down below the splines (very messy unless you have that expandable rubber plug from the kit) but it will be back in 60 days. I would check the bushing bottom colum and replace ittermet shaft with the latest design, 

[Mossyoakglock]

We don't have a Les Scwab down here and every place here charges a diagnostic fee. I might have to go that route if I can't track it down. 

 

I had read about the bushing on the bottom of the column as well. When I hear the clunk, I don't feel anything in the steering wheel. If I do replace the steering shaft I might as well replace the bushing since I'll have the shaft out. 

 

At one point I thought I felt the clunk in the driver's floorboard but it could have just been the road.

 

Edit: I just looked and it appears that the new, updated green bearing was only for the 800 platform, not the 900s.  

Edited December 16, 2021 by Mossyoakglock
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