Takeoff driveline shudder/shimmy

[2021QCBH]

2026 CC/6.5 Hurricane 4x4

Well, didn’t make it to 1000 miles before the first real issue. Needed to tow this weekend so I hooked up about 4000lbs. Highway and acceleration is fabulous and overall towing is great.

I was mostly running highway on the first part of the trip. The 2nd part is 2 lanes so some stops. On medium acceleration as the truck passes through about 5 mph range it has a pretty healthy shudder/shimmy. No other odd vibrations and is smooth as silk otherwise. Frequency seems to be about how fast the driveshaft would be spinning at very low speed. This is a 2 piece with a carrier bearing so I’m assuming it’s got issues with the slip joint or something.

I thought it may be green torque converter clutches during lockup but I confirmed lockup happened after the shimmy issues. Lockup happens just after the shift to 2nd and the shimmy stuff is all very low speed in 1st gear.

Off to the dealer it goes…..

 

[RiffWrath]

I have no experience with towing. I use friends trucks for that sorta thing

Did you turn on or off the Tow Mode switch while this shimmy was happening?

I’m unaware whether your model even has one but asking anyway.

 

[2021QCBH]

Tow mode is weird with the new drive modes. You select it via the dash and it auto engages 4 auto. Don’t want that on but the shimmy goes away in 4 auto like I’d expected since it’s putting less power through the rear driveline. I leave it in auto towing and it does just fine so I don’t see the need for tow haul and adding unnecessary 4x4 shifts.

 

[RiffWrath]

Tow mode is weird with the new drive modes. You select it via the dash and it auto engages 4 auto. Don’t want that on but the shimmy goes away in 4 auto like I’d expected since it’s putting less power through the rear driveline. I leave it in auto towing and it does just fine so I don’t see the need for tow haul and adding unnecessary 4x4 shifts.

I wasnt aware thats how tow/haul mode worked. I just thought it held lower gears a bit longer and engine braked when coming to a stop.

I use it cause it makes my truck sound meaner with the GT exhaust. Sounds cool when im slowing at a light. Sounds growly.

Thats all it does on my 22 GT anyway.