Clunky rear end when hitting bumps in the road

[Zach]

What could be some culprits of this? It sounds like something is loose, but I can't find what it might be. Things I've checked...

 

The bed is solidly mounted to the frame

Exhaust is solid

Nothing obviously loose under the truck

Nothing is in the bed of the truck

 

It kinda sounds like it could be coming from the driver's side...could it be a suspension part? Wondering if I need to change out some bushing back there. Thoughts welcomed.

[Thomas Perkins]

You live in Atlanta,cool.I live close to Columbus.Do you ever come there.If so stop by the house in your 720 and you can check mine out.I live in Ellerslie,google map it.It is 13111 Warm Springs.Rd.Are your tires leaning in.Mine was long time ago,I took it to Columbus Springs and they fixed it.It was causing the inside of my tires to wear.That was back in 2009.It wollered the hole out and he welded it and put new bushings in it.I had new poly put on and they still look new and it rides smooth.Don't believe that rubber is better,rubber wears out.I've had these on for 14 years.My tires wear even and I get over 60,000 miles from them.People on here may say other wise but I've had my 720 for 29 years.I know.I also had new ball joints put on.I put Rancho shocks on front and rear long ago.

Edited March 14, 2023 by Thomas Perkins

[bottomwatcher]

Check to make sure your spare tire is tight to the frame. A loose spare tire will make a dull thunk.

[wayno]

Check the U-joints and play in rear axle, you will likely need to remove the driveline to check the U-joints properly.

[datzenmike]

On a bump?

 

Loose shock absorber.

Stone caught between bed and cab.

Broken leaf

Loose U bolt.

Loose lug nuts.

[DwayneOxford]

Had similar noise in 2WD, figgerd it out when ball joint gave up.

[datzenmike]

Clunky rear end when hitting bumps in the road

 

No ball joints back there and I don't think a loose differential or U joint would do this only on bumps.

[jagman]

If your spare tire is still under the bed of the truck check to see how tight it is to the frame.  Mine loosens slightly over time and causes a noise when the road is rough.

[powderfinger]

It's also very common for your tailgate to make noise when hitting bumps if it isn't closing tight which is very common. Not sure I would describe that sound as a clunk though. Either way something to check.

[Stoffregen Motorsports]

Also check for loose U-bolts.

 

Shock bushings that aren't tight enough will clunk over bumps.

 

Agreed on the tailgate and spare tire. Those are the most likely causes of a rear end clunk.

 

I have also seen loose fuel tank filler necks hit the body over bumps.

[DwayneOxford]

Long ago learned that location of such noises is deceptive.

Suggest you ride in bed and listen.

[datzenmike]

 

Back in the '60s a friend's dad worked for a large Ford dealership in Toronto and they had a customer complaint of a strange sound that they couldn't find. It was a '50s sedan and they took everything apart and the customer had it in and out of the shop and every mechanic took a try finding it to no avail. Eventually Ford bought it back and it sat in the back of the lot. On occasion a mechanic would try his luck on it but generally that car beat them every time and it was hated. Well one day a mechanic got the great idea of riding in the engine compartment while someone drove it around. This particular ford had the hood that hinged at the front so he laid across the engine and the went for a ride, sure enough the sound was there. Having a hard time maintaining his balance the mechanic reached over and grabbed the radiator cap.... and the noise stopped!!! 

[Stoffregen Motorsports]

That's a great story. Buy-back for radiator cap.

[Zach]

It was the spare tire.

[datzenmike]

[bottomwatcher]

What do I win?

[iceman510]

See the "winning" thread.

 

 

Edited March 22, 2023 by iceman510

[datzenmike]

A free Georgia emissions approved burn barrel.