Slow/idle speed back and forth roll

[redgst]

2019 2500 w only 900 miles.

I've noticed now randomly when I'm at a slow almost idle speed the truck feels like it's on oval tires / has a slow/fast forward movement.
It's not a shake or death wobble tho from what I've read... And as soon as I give it some throttle... It's all good.

Any thoughts?
Thx

 

[tron67j]

Could be a high spot on a brake disc. Brake discs don't warp, what happens is tiny bits of metal from road debris gets thrown up on the disc and the heat essentially welds the metal to the disc. This is the wobble/thump that people feel, that little high spot passing by the pads. Possibly what you feel, as the spot moves past the pad wheel rolls more freely and, with same or no pressure on brake pedal when that spot gets to the pad, the pads now have something to grab. Turning a rotor essentially smooths the surface again, it cannot/would not fix a rotor if it were to warp.

 

[crash68]

Brake discs don't warp, what happens is tiny bits of metal from road debris gets thrown up on the disc and the heat essentially welds the metal to the disc.

Close but the material that builds up on the rotors is from the brake pads themselves. It's more likely to happen if you brake hard and keep the pads against the rotors in one spot.
Another cause which people call warping is uneven torque of the wheel lugs that causes lateral run-out

 

[RandomRam]

Feels almost like a jerk from a manual transmission in 1st gear at idle?

 

[tron67j]

Close but the material that builds up on the rotors is from the brake pads themselves. It's more likely to happen if you brake hard and keep the pads against the rotors in one spot.
Another cause which people call warping is uneven torque of the wheel lugs that causes lateral run-out

Yep, that does it too.

 

[Hydraplane]

In just about every one of these "new Hemis" I've owned, when just off idle in 1st gear the RPM will hunt.

 

[pacofortacos]

With that low of miles, if it sits a lot, it could be flat spots on the tire. Usually takes some driving for them to go away.
I run into it all of the time as my truck sits for weeks on end.