poping noise from rear axle going over pot holes

[wicsmith1997]

My Ex-Father in-law whom I get along with well informed me he hears a kachunk noise every time I go down his driveway and for every pot whole I hit. After 5 - 10 minutes of jumping on the bumper and shacking the vehicle at park was finally able to reproduce the sound.

If you put your foot on the receiver ball and push it toward the tire opposite the side your on and grab the wheel well and rock the vehicle side to side it starts to make a metallic popping sound which sounds like its coming from behind the wheel rim.

Best way I can describe this sound is if you've ever had a thin piece of metal that had a concavity to it and you was able to pop that concavity back and forth that is similar to the sound I am hearing.

Our guess is its some play in the Axle. Does this sound correct to you all? Does it sound normal?

1997 4.0L ohv 223k miles, 4x4 with control trac
Vehicle seams to run fine otherwise, Strait no sensation of drifting while driving. No odd rumbling noises while driving.

Any helps or suggestions appreciated.

 

[my pos mounty]

The "side to side shake test" you describe will always result in a "clunk" from a solid axle vehicle.
What you hear is the inevitable slack in side to side motion due to the design of the rear differential. The axles come closest together in the middle of the carrier. They are held in place by circlips. To prevent those circlips from dropping off there is a cross pin that goes between the ends of the axle shafts, basically pushing the axles outward, holding the circlips in a groove in the spider gears. The clunk is created by the axles sliding back-and-forth and smacking the cross pin. Nothing to worry about with that noise.
I would look on the passenger side of the rear axle assembly and look for the "third shock". If you have this attached to the rear axle assembly, that could be the source of your noise.
Other things to check are your rear shocks, their mounting points and your u-joints on the rear driveshaft. This is all assuming that the noise he hears IS coming from the rear of the truck.

That pic clearly shows the circlips, the spider gears and the axle end. The cross pin was removed when I took this pic since the pic was for illustration purposes of where the circlips are. The cross pin goes down the middle of the axle ends.

 

[ahodges]

Well I would agree that the noise you are talking about hearing is most likely the "third shock". It's a sway dampener that attatches horizontally from the rear axle to the frame. It is common for these to adventually go bad. Like my pos mounty said it could also be your rear shocks. My money is on the third shock.

 

[wicsmith1997]

I've never heard of this "third shock" I'll have to Look into that possibility this weekend. Is this "third shock" unique to explorers?

 

[ahodges]

Only the 4 door explorers and mustangs have them I hear..