What causes the rear differential to jump up and down rapidly going down the road?

[The motor guy]

I was behind a chevy Tahoe and you saw daylight under the tires as it would shimmy up and down rapidly at 60mph. Maybe like 1/2" of travel up and down would be my guess

 

[Astro14]

Worn out shocks and badly balanced tires.

 

[spackard]

In addition to the above, overinflated tires will help exaggerate the bounce.

 

[UncleDave]

It could be a number of things.

Even a brand new rig can exhibit axle hop on certain freeways.

 

[dishdude]

If you see a tire bouncing up and down like a basketball on the highway it's a blown out shock or strut.

 

[The motor guy]

If you see a tire bouncing up and down like a basketball on the highway it's a blown out shock or strut.

Wow because that was a pretty late model Tahoe. 2017 maybe?

 

[dishdude]

Wow because that was a pretty late model Tahoe. 2017 maybe?

6 years old, who knows how many miles.

 

[The motor guy]

6 years old, who knows how many miles.

True. Guess the shocks are still good on my dodge at 17 years and 217,000 miles

 

[ctechbob]

True. Guess the shocks are still good on my dodge at 17 years and 217,000 miles

Probably not. You might not experience the hopping axle, but rest assured they're not damping like they did when they were new.

 

[dumkid]

Lumpy tires? Even out of balance tires don't usually cause severe vibration, just annoying vibration. The shocks could be blown but it takes more than blown shocks to make the wheels hop

 

[Chris142]

Separated tire

 

[The motor guy]

Probably not. You might not experience the hopping axle, but rest assured they're not damping like they did when they were new.

No but it still goes down the road good enough lol

 

[The motor guy]

Separated tire

It was both side evenly. Really easy to see when they have that antisway bar on the back of the differential

 

[JHZR2]

Probably not. You might not experience the hopping axle, but rest assured they're not damping like they did when they were new.

I was surprised how firm and hard to compress the original shocks are on my 1991 Mercedes, when I took them off back in May. I was expecting to replace them, and coukd barely compress them enough to do the reinstall. Bilstein or Sachs…

 

[The motor guy]

I was surprised how firm and hard to compress the original shocks are on my 1991 Mercedes, when I took them off back in May. I was expecting to replace them, and coukd barely compress them enough to do the reinstall. Bilstein or Sachs…

I pull a trailer around with 1100 pounds I'd tongue weight with my 2500 ram and it does fine still.

 

[pcoxe]

Worn out rear universal joint causing the drive shaft to become unbalanced.

 

[tblt44]

No to Universal joints but could be a tire or shock issues

 

[Trav]

I was surprised how firm and hard to compress the original shocks are on my 1991 Mercedes, when I took them off back in May. I was expecting to replace them, and coukd barely compress them enough to do the reinstall. Bilstein or Sachs…

That car came from another time and universe compared to many of today's cars.