Noise from rear end suspension...

[Frankd1]

I noticed a new noise tonight, its a tapping or dull subtle thumping (best I can describe it) coming from the rear end when I go over bumps in the road.

I checked the end links for the rear sway bar when I got home and its not those. In fact, I replaced those end links a few months ago and they are still nice and tight when I grab hold of them and try to move them. The old ones were loose and made a racket, these new moogs seem great so far. I also replaced the rear swaybar bushings with polyurethane bushings from Prothane.

Once home I pushed down on the rear bumper repeatedly to try and replicate the sound. I was able to get the noise to come back - it seems to be coming from the passenger rear and is in sync with pushing down on the bumper. its as though two components are contacting each other as I push down and that's when you hear it....
The rear struts seem good though because there is no bounce when you push down and let go. The noise seems worse inside the truck when driving vs hearing it from the outside when I push down on the bumper.

I did have to push down quite firmly and use a bit of force to hear it. Maybe that's why it sounds worse when driving over bumps because the struts and springs are experiencing more compression forces than I can create with my arms?

I know this is tough to diagnose from reading a description on a computer screen, but has anyone come across this?

What other components in the rear suspension tend to make those noises?

Thanks

 

[Wooluf1952]

Check the bushings on the panhard bar.

 

[Frankd1]

I'll check the panhard bar as well as the control arms...I'm guessing the best way is to lift the rear end and support with safety stands, then gab the bar and see if there is movement in the busing? Or, can it be done weight on wheels?

I did replace the swaybar end links a few months back but I will check those as well, I'm sure its entirely possible that one of the nuts came loose a bit.

Thanks

 

[The_Roadie]

The Panhard bar resists side to side movement, so you can push the body sideways and see if that stresses the bar mounts enough. Or you could have a crack in a control arm mount, loose anti-sway bar end links, broken/loose bar bushing bracket, internally broken shock or loose shock bolt (missing shock centering tube/spacer), coil spring with a missing rubber isolator on the top, or even looseness in the spare tire carrier or some road debris rattling on top of the spare.

You might take one of the anti-sway bar links off to eliminate or focus in on that as a cause.

 

[kickass audio]

I am willing to bet it is your sway bar end links that are shot. Best way I found to see is to crawl under the truck and take your fist and hit on the sway bar where the end link attaches. If it rattles then you have bad end links and need to replace them. I found my original ones failed at 115k miles and I tested them on a bumpy road as well as just sitting in my driveway in park with the truck resting on the ground they rattled when I hit them with my hand. They should not rattle at all. But it could be like roadie said and you may have a bad bushing, never know until you crawl under and look.

 

[Frankd1]

I checked everything as suggested - all of the rubber bushings are intact and in good condition, all mounting brackets and hard points are solid with no corrosion, no cracks.
Nothing rattles, squeaks or wiggles.

I lowered the spare tire and raised it again nice and snug….after doing this the noise is gone! It had to be related to the spare tire carrier, I'm thinking some slack developed in the cable which caused the spare to knock around a bit when driving over bumps.

So, I guess I can consider this solved for now. If everything else checks out, have a look at your spare!

 

[The_Roadie]

Thanks for the report. First time that idea was actually the cause, but I haven't suggested it too many times. Sort of like mystery squeaks in the front end that end up being the hood stops.

 

[Frankd1]

No Problem!

Before I lowered the spare I slowly tried to turn the crank rod clockwise to see if the carrier was loose. There did seem to be some slack there....
I lowered the tire all the way down because I wanted to check up in that area anyway, and sure enough all was good. I raised it up again nice and snug and there hasn't been any noise since...

It must have worked itself loose somehow over time. Hopefully these carriers don't fail and I end up dropping the spare on the highway

 

[kickass audio]

I see you fixed it with your spare tire but did you check the tire pressure while down? My dad's tahoe has a slow leak on the spare tire and when it gets too low like less than 20psi the carrier is up all the way but it will wobble around. it sounds like a rubber mallet being hit on the frame when it moves around when low.

 

[Frankd1]

I didn't check the pressure, but good point and thanks for the reminder. I will do that today!