The steering clunk associated with the half shaft issue the 2000+ Bonnevilles have is noticeable when turning at low speeds, like in a parking lot. It can, and will, happen on perfectly smooth driving surfaces. The clunking Justin is referring to will occur when going over bumps at road speed.

It'* not that, but thanks for the suggestion. The clunk sound is coming from under the driver-side floorboard and/or the driver'* side steering mechanics. Everything stated online fits this problem'* symptoms, but for some reason the Technical Service Bulletin for this Gm problem doesn't include my 1998 Pontiac Bonneville SSE. Not as far as I've seen. I called for the lube kit at a GM dealership, for a 1998, and the part number matches the one for this respective TSB. The bulletin mentions 2000 Bonneville, but not the 1998 so my questions are, shouldn't it? Is there something I'm missing? Is the relube procedure any different with my vehicle than the common way?

Steering - Steering Column Clunk Felt/Heard on Turns
Bulletin No.: 06-02-35-010
Date: May 09, 2006
TECHNICAL Subject:
Clunk Felt/Noise Heard From Steering Column, Steering Gear and/or Front of Vehicle During Maneuver and/or Steering Wheel Rotation (Replace Intermediate Shaft)
Models:
2001-2004 Cadillac Seville - with RPO JL4
2001-2003 Oldsmobile Aurora
2000-2005 Pontiac Bonneville
Attention: This bulletin ONLY applies to the above listed vehicles. All other cars with a similar condition should refer to Corporate Bulletin Number 01-02-32-001G.
Condition:
Some customers may comment on a clunk type noise coming from the front of the vehicle while driving during a turning maneuver. This condition may also be felt through the steering wheel when the vehicle is stationary and the wheel is rotated from steering stop to steering stop. Some vehicles may only exhibit the noise once for every 360°of wheel rotation. On all other vehicles, this clunk noise will be noticed during low speed acceleration or deceleration, typically in light turns of the steering wheel.
Cause:
This condition may be caused by inadequate lubrication of the steering intermediate shaft which results in a slip stick condition possibly resulting in the clunk noise.

Read this thread:

https://www.gmforum.com/2000-2005-90...re-ask-223290/

I should mention, mine has been doing that for 10 years. It has never gotten worse.

Can you refer me to the information that applies to my year 1998? Also, the previous owner had a similar problem and the half shaft was replaced. I'm trying to figure what exactly this is. Thanks!

I know when i worked at the chevy dealer they kept changing the bulletins they started having us replace them then grease them then replace them then grease them. I dont think they ever found a real fix.

I saw videos on how to lubricate this, but not specifically for a 98 Bonneville SSE. I just need the simplest solution, I will try to tackle this tomorrow per cliche instructions, hoping my car is built the same way. If anyone knows tips please let me know. I will also keep searching this forum.

I'm starting to think this is the half shaft, even though most symptoms point to the intermediate steering shaft. I know these facts:
The half shaft was replaced once already about 5 years ago;
The clunk sound started while turning corners, now sounds also when going forward or backward from a stop, or stopping;
Clunk sound is not always present, and is worse some days then others;
Sound is not felt through the steering wheel, but instead through the floor boards;
TSB which points at this problem, isn't for this year vehicle;
Mechanics say it'* the rack, or they don't know.
I will try to get a third opinion today.

How to test to see if it is the intermediate shaft:

1. Locate a large area (parking lot) where the vehicle can be turned in a tight circle.
2. Turn the steering wheel to the right and/or left all the way to the steering lock, then off the steering lock a 1/4 turn.
3. Drive the vehicle approximately 5 km/h (3 mph) in a circle, preferably over rough pavement or seams on the road surface.
4. If a clunk is felt in the steering wheel, the MOST likely cause is the I-shaft - not the steering gear.