"clunk" under drivers floor board

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sleepdoc

10 Year 15 Year
Joined
Oct 12, 2010
Threads
57
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253
Location
Edmond, OK
I have been hearing a clunk under my 01 LC (184K) for a few weeks. My go-to cruiser mechanic. Dirtdawg, has moved to Colorado so I have been forced to get advice by text and find someone else to do the work. The new guy put it up on rack today and checked everything from sway bars to control arms. He only saw a little play in the upper control arms and suggested we do those if I can't live with the clunk.

Clunk happens routinely when I brake fast at a stop light or accelerate from a stop. I also feel the thud under drivers floor board. All bushing are original and do not look bad but he also suggested changing sway bar bushings while he had it since they are relatively cheap and easy.

No squeaking at all just the clunk and feeling a thud.

It is just a daily driver with no intentions of going off road.

Thoughts on other things to look for? Thanks for help.
 
Could very well be the inner sway bar bushings.
 
Do you have sliders?
 
Ramathorn15 said:
Do you have bolt on sliders. I hit mine pretty hard at 100s and the top of the frame bracket got pushed close to the body. I could feel them hitting the floor board periodically.
Click to expand...

Same here. I had to loosen mine and pull them back down so there was the 1/2" gap to the rocker.
 
Possibly your diff bushings or steering rack bushings.... have same noise since 100s and those are (at least I’m pretty sure) the culprit. Check driveline as well
 
Sleepdoc- as you can see from all the various assessments; posting the d’tails: year & mods on your truck in your sig line helps keep guessing to a minimum.
 
Have you checked the play on your cv shafts / drive flanges?

This is my 100 when I brought it.





sleepdoc said:
I have been hearing a clunk under my 01 LC (184K) for a few weeks. My go-to cruiser mechanic. Dirtdawg, has moved to Colorado so I have been forced to get advice by text and find someone else to do the work. The new guy put it up on rack today and checked everything from sway bars to control arms. He only saw a little play in the upper control arms and suggested we do those if I can't live with the clunk.

Clunk happens routinely when I brake fast at a stop light or accelerate from a stop. I also feel the thud under drivers floor board. All bushing are original and do not look bad but he also suggested changing sway bar bushings while he had it since they are relatively cheap and easy.

No squeaking at all just the clunk and feeling a thud.

It is just a daily driver with no intentions of going off road.

Thoughts on other things to look for? Thanks for help.
Click to expand...
 
The play on my 100 is pretty bad.... The splines on the drive flange are worn-out pretty bad. It can sound pretty gnarly when you coast and hit the accelerator or when you go from drive to reverse when stopped. (that's what i was doing in the video). Attached is a picture of the drive flange and the splines that tend to wear out.


shoboat90 said:
Forgive my ignorance, but is this play in the video bad or normal?
Click to expand...

SmartSelect_20180909-070618_Google.webp
 
THanka for input.
No sliders.
Mechanic said cv looked good. No cracks in boot. There was some grease on both sides but he thought it was from over greasing the zerk above the boot. (Sway bar maybe?)
I definitely feel it under my feet. We didn’t see any play in LCA, only Upper.

He didn’t look at differential bushings which is also what @DirtDawg suggested. I will get those checked too before we do anything else.

And I will try to do a description in my signature so to alleviate some of the questions about my set up.
 
shoboat90 said:
Forgive my ignorance, but is this play in the video bad or normal?
Click to expand...
New OEM front drive shafts, hub flange and cone washers has near zero play.
 
Worn hub flange teeth are more readily visible from back side. Number one cause for this is improper wheel bearing service.
Hub flange teeth worn.webp

New hub flange.
Hub flange new (2) 06LC 196K.webp


Clunk from worn hub flange & axle is associated with shifting from D to N to R with foot on brake.

Thud clunk when slowing then accelerating without stopping "Propeller shaft clunk thunk" is associated with under greasing aft or forward slide yokes of propeller shafts.

Stabilizer (AKA sway bar) worn bushings & links are associated with lack of stability on winding roads.

sleepdoc said:
THanka for input.
No sliders.
Mechanic said cv looked good. No cracks in boot. There was some grease on both sides but he thought it was from over greasing the zerk above the boot. (Sway bar maybe?)
I definitely feel it under my feet. We didn’t see any play in LCA, only Upper.

He didn’t look at differential bushings which is also what @DirtDawg suggested. I will get those checked too before we do anything else.

And I will try to do a description in my signature so to alleviate some of the questions about my setup.
Click to expand...
No grease zerks in CV boot area of a stock front end suspension. Some aftermarkets ball joint, UCA or LCA do have grease zerks. If these aren't grease regularly, they may develop a clunk as you described.

Bad UCA or LCA bushing could have a hard stop a or heavy footed acceleration THUNK. @DirtDawg knows his stuff, now a second has confirmed. YOU know what needs done!
 
All good suggestions so far on what the clunk could be, all I shared with @sleepdoc to pass on to his mechanic. Just for reference, things that I know are good since my last servicing on the rig:

-CV shafts and flanges show no play and wheel bearings are tight (recently repacked)
-When I had it last, no excessive play in the front end (BJs, bushings, steering, etc.)
-Driveshaft was lubed every time it came in

As I mentioned in private conversation, I would first check sway bar bushings/hardware and front differential mounting bushings. Once those are ruled out, I would start chasing a potential suspension issue.
 
Yet another reason I love Mud- I had some drivers footwell knocking, similar to earlier poster my mechanic couldn’t find anything loose. hub flanges replaced a month ago, no leaky cvs.

Just checked and Sure enough my driver side slider front bracket had worked its way upwards, likely due to a couple of big hits at cruise Moab. Thanks @Ramathorn15 (owl expedition FTW)
 
I’m hopeful that my clunk was also my slider. It was definitely touching the cab, so I loosened them up, readjusted them, and shimmed the top of the front mount with a 1”x1/8” piece of flat stock to angle the slider away from the cab. Hopefully that’s all that it was. It’s been driving me nuts. Thanks to those who suggested that.
 
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