Found my Clunk Clunk noise

[JayMan]

Well, starting about two months ago, my GMC Sierra started making the dreaded CLUNK CLUNK noise. Most noticeable at low speeds, especially over potholes and speed bumps.

 

Checked the bushings on the frame for the front torsion bars. Fine.

 

Checked the rear driveshaft yoke. Fine.

 

Broken spring? No

 

Loose u-bolt for springs? No

 

Loose shackles? No.

 

Steering intermediate shaft? Fine.

 

This was driving me bonkers.

 

Finally, managed to figure out it would make the same noise in Park if I really bounced the rear, but not the front. So I tracked down a couple of friends who are, and I'm being VERY polite here, "gravity challenged." Real nice fellows, just the "mass" I needed.

 

Back in my heated shop, I rolled around on my creeper and had their combined 500 lbs of weight bounce the rear end in unison.

 

The nice Rancho 9000x shocks I put in last fall were making the noise!

 

The lower bushings in both shocks are kaput, soft and mushy. So the noise was metal-to-metal contact.

 

I had kept the OEM shocks and put the OEM rear back on. No more noise.

 

So after spending all that money on those nice shocks, they do that to me.

 

We learn something new every day, don't we??

[lrymal]

So after spending all that money on those nice shocks, they do that to me.

I think it would be time to contact Rancho. These are the bushings that you place the bolt through, right? Heck, those bushings are cheap. Just press the Rancho ones out and replace them.

 

But, I'd still contact Rancho.

[JayMan]

Yep, those are the same bushing in the eye where the bolt goes through.

 

Still waiting to hear back from Rancho. I suppose I could use my press to press in new bushings, but for what I paid for those things, I'm really ticked.

 

I got the Rancho 9000x shocks just to get a better ride. I always leave them set on "1" or Soft.

 

With the OEM shocks back on the rear, the ride is noticeably stiffer. Good thing I still need the 6 sandbags in back for winter traction.

 

I've had old shocks do that to me, but that was like +20 years ago. Usually by the time the bushings were shot, the shock was leaking and ready to be tossed out.

[lrymal]

I got the Rancho 9000x shocks just to get a better ride. I always leave them set on "1" or Soft.

Yeah, usually, the bushings are the very, ultimately, last things to go out on a shock. Kinda weird. But, I remember when I got my Ranchos that the bushings were not all the same. They had different shines, or something---as if they were not of the same batch. I'll keep an eye out on mine.

 

I keep my front setting on 4 and the back on 3. For me, anything less on the front makes the truck too "floaty". I recall how amazed that I was that having the back on 5 or above affected the ride more than the front, especially when hitting expansion joints. Anyway, it is a grand ride.

 

Your experience has made me decide to keep my Monroe Reflex shocks which I was going to sell---the Ranchos replaced them. Hopefully, the Reflexes will be on storage shelf for a LONG time.