2017 Sport CC Rear End Wobble

[Bigskyroadglide]

If you just replaced rear rotors, I would suspect one of those could be out of spec. I've seen them warped out of the box new

 

[Daniel12]

If you just replaced rear rotors, I would suspect one of those could be out of spec. I've seen them warped out of the box new

This has been present from the last rotors and these rotors. I guess they still could be the culprit. I’m not sure what the acceptable runout is on one of these rotors. I used a dial caliper and measured 7 thou on the outer edge of the rotor on my rear driver side which is where it feels like the vibration is coming from.

Do you guys think this vibration could be from a driveshaft? Or are driveshaft vibrations typically a more intense and consistent vibration?

 

[Bigskyroadglide]

Op if I read all the information you have posted correctly, this is a 2017 4x4 crew cab with air suspension. You've recently installed rear control arms and brakes and rotors and have had your tires road forced balanced
All in an effort to get rid of a shake at speed. You've loosened the rear parking brake pads and this helped but the shake is still present. You found a rub mark in your gas tank and evidence of it being rubbed by the driveshaft. So, if this summary is correct,

I'd focus on why the drive shaft rubbed the tank. Which is a real question.

All your other efforts have not solved your issue.

In addition, if you have a crew cab, I believe you have a carrier bearing which could be bad causing driveshaft vibrations and letting it hit the tank.(??)

So short of mounting a gopro under your truck to watch for vibrations that’s my mechanical thoughts.

As to tires, even roadforced balanced, will not compensate for a broken belt or a flat spot in a tire. Have you moved front to back to eliminate this variable?

Good luck

 

[Daniel12]

Op if I read all the information you have posted correctly, this is a 2017 4x4 crew cab with air suspension. You've recently installed rear control arms and brakes and rotors and have had your tires road forced balanced
All in an effort to get rid of a shake at speed. You've loosened the rear parking brake pads and this helped but the shake is still present. You found a rub mark in your gas tank and evidence of it being rubbed by the driveshaft. So, if this summary is correct,

I'd focus on why the drive shaft rubbed the tank. Which is a real question.

All your other efforts have not solved your issue.

In addition, if you have a crew cab, I believe you have a carrier bearing which could be bad causing driveshaft vibrations and letting it hit the tank.(??)

So short of mounting a gopro under your truck to watch for vibrations that’s my mechanical thoughts.

As to tires, even roadforced balanced, will not compensate for a broken belt or a flat spot in a tire. Have you moved front to back to eliminate this variable?

Good luck

Thanks! Yes 2017 Ram 1500 with air suspension. It is a crew cab with a short box so it has a 1 piece drive shaft.

Measures taken so far:

- New tires (Michelin Defender LTX) with 3 rounds of RoadForce balancing. All with 18lbs or less of roadforce
- Alignment which noted one of the rear tires was toed in a bit, which led to the new control arms
- New brakes, rotors and parking brakes with all new hardware (about a year ago)
- Rear upper and lower Freedom Offroad control arms (yesterday)
- Front CV axles (passenger side has a bit more play on the intermediate shaft than the driver side but that doesn't seem to be the location of the vibration) about a year ago
- Backed the parking brakes all the way off which helped with the vibration from 0-100kmh (yesterday)

The driveshaft never made contact with the fuel tank. There is a little gouge out of the tank and a mark in the corresponding spot on the driveshaft around the whole circumference. The driveshaft is not able to flex anywhere near enough to make contact with the tank so I'm assuming something flew up from the road and made the mark on the tank.

I'm going to try swapping wheels and tires with a friend who has a Ram with no vibration, and see if that cures the issue. If not, then I'll remove the front and rear driveshafts and get a driveline shop to balance them and possibly replace the U-joints if needed. Short of this, I'm almost out of ideas lol

 

[Bigskyroadglide]

Well, it appears you have checked the boxes. It may be unsolvable but, even Michelins could have a broken belt or a flat spot. Hopefully the tire swap will reveal something.

In my opinion, It would take a good size rock to damage a driveshaft enough for it to be out of balance.