LMM: Chasing a clunk

[gpn]

I have a new clunk noise that has been getting worse. Truck is the LMM in signature with ~154k miles. Been leveled for most of its life but ran the stock z71 tires until 142k miles. Now it has 285/70r17s w/ 17x9 wheels.

My steering box had some play so I replaced it with a reman which sucked so I quickly replaced that with a redhead, which is awesome. The reman box didn't change the noise so I also added kryptonite lower ball joints and tie rods from dmaxstore. The UCAs are kryptonite from dmaxstore as well and those were installed at 142k miles. I grease the fittings regularly when I change the oil and when I rotate tires (works out to every 4-5k miles).

The clunk appears to be coming primarly from the driver side and it only occurs when there is significant side load during a turn. If it clunks on a right turn it won't do it again until I make a left and it shifts again. If I keep turning the same way it will only clunk the first time. I had the whole wheel assembly off to put the lower ball joints and tie rods in yesterday and tightened everything back to the standard torque specs.

I've googled around and the only thing that even sounds remotely close to my problem had something to do with the body mounts. The clunk reminds me of someone smashing the imaginary brake on the passenger floorboard. But it comes from the driver side.

 

[RPM Motorsports]

Sure it's not the steering shaft? My LBZ would do it at a slight left turn and while hitting a bump. Also had a clunk from the torsion bar cross member bolts loosening.

 

[WVRigrat05]

My LMM does the same thing, I learned when I had it towed the other day that the LCA bushings have some play and t bar crossmember bushings are shit. Jack up at the frame and stick a bar between the frame and LCA and try that, also the crossmember. If that's not it, it's most likely cab mounts.

My trucks always been leveled and has 100k, and is mostly highway so I'm sure yours is about like mine with the higher miles.

 

[gpn]

I had a similar clunk in my LBZ that I sold before I fixed it. On that truck the plastic steering bearing rattled and I replaced the intermediate shaft and bearing and that stopped the steering column rattle but didn't fix the clunk.

On the torsion bar cross member I checked the rivets into the frame and they all appear tight. Any other bolts that loosen up?

The bumps on the road don't change the clunk at all and I live in Tucson where the roads are horrible and bumps are everywhere. My LMM is super smooth over the bumps especially since I replaced the UCAs. I could also describe the clunk as a crunch noise.

 

[WVRigrat05]

I had a similar clunk in my LBZ that I sold before I fixed it. On that truck the plastic steering bearing rattled and I replaced the intermediate shaft and bearing and that stopped the steering column rattle but didn't fix the clunk.

On the torsion bar cross member I checked the rivets into the frame and they all appear tight. Any other bolts that loosen up?

The bumps on the road don't change the clunk at all and I live in Tucson where the roads are horrible and bumps are everywhere. My LMM is super smooth over the bumps especially since I replaced the UCAs. I could also describe the clunk as a crunch noise.

The rivets will be tight, the bolts that hold the crossmember in go though some cheap rubber bushings, the ones in my LLY were completely gone at 200k.

 

[gpn]

Have you replaced the LCA bushings yet? What you recommend for replacement bushings? I'll check the t bar bushings as well.

 

[WVRigrat05]

Have you replaced the LCA bushings yet? What you recommend for replacement bushings? I'll check the t bar bushings as well.

I have not, have too many other projects going on and backs ****ed up again, I plan on doing poly (or some type) of poly bushings. Rubber seems to get too soft too quick.

The GM replacement bushings for the t bars only last about 30k when leveled from my past experience, def need a poly bushing or the stuff you can buy and cut your own.

 

[gpn]

Can I swap the bushing without unloading the torsion bars? Think I might do that and see if it fixes the problem.

 

[WVRigrat05]

Can I swap the bushing without unloading the torsion bars? Think I might do that and see if it fixes the problem.

You'll have to pull the t bars

 

[RPM Motorsports]

Take the pre load off, pull the keys, slide torsion bars forward about 4". The crossmember will drop out after the two outer bolts are removed.

 

[TheBac]

You dont need to pull the torsion bars to replace the crossmember mounts.

http://www.dieselplace.com/forum/71...ar-support-crossmember-mount-replacement.html

 

[kubitza123]

I'd say the steering shaft as mentioned above , the bushings mentioned above, or if it does it when you drive over some washboard type shit hold the brake pedal with your left foot and see if it goes away.

I noticed on my 04 that when I hit washboard the brake pedal has enough play makes damn clunking noise as well.

Also check your brakes since they have also been known to clunk/rattle.

 

[oscyjack]

Sounds like the iss and column bushing to me. You're due for lca bushings too at this point

 

[NC-smokinlmm]

I believe there was a recall on the cab mounts for the 08. Mine were replaced by GM in 2011, it was rattling and clunking in turns and small bumps.

 

[gpn]

I swapped in a set of 905-509 t-bar bushings and no change. The old ones were in great shape with 153k miles and most of that time with leveling keys installed. Now I have a TPMS sensor going out. I'll probably get that going and just go on my road trip with the clunk.

 

[WVRigrat05]

I'm very surprised they weren't bad.

My control arms have about 1/4" of movement can't duplicate a rattle though.

Did flex my cab hard in my yard (never done that) it popped and creaked like hell, think I found my thud.

 

[carl.swoyer]

Check out you intermediate shaft on the steering column.

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