Resolved 2G AWD Driveline shuddering

[Jon Lane]

2g Tsi. Original LSD rear and axles, 190k mi. Rebuilt trans and TC 2k mi ago. 70k on carrier bearing, U-joints, rear wheel bearings. Just filled gearbox with 75w140NS and TC with Lightweight Shockproof.

Car developed a driveline and/or road shudder today with no previous symptoms. Completely throttle invariant; it happens increasingly as speed rises above about 25mph. Appears to come from center-rear of car, possibly rear. Feel it in the seat. Gets fairly bad by 45mph.

Anyone ever have this happen?

 

[danl]

Yes.

Bad carrier bearing, universal joint, or driveshaft weight fell off.

I’ve also seen it happen when the driveshafts are not at the correct angle, so make sure the nuts holding the carrier bearing to the studs are tight and the bushings are in good shape.

 

[Jon Lane]

Appreciated. That sounds right because the frequency is too high to be a wheel or axle rotation. It's uniform across the floorpan too, so it's not localized at one hub or the other.

It happened suddenly - might a carrier bearing or U-joint fail all at once? I'm thinking driveshaft weight right now...

 

[Jon Lane]

It was a split U-joint cap, the one at the diff input.

(For reference, if the car suddenly makes a mild rumbling or shuddering, worsening as speed rises, check the U-joints. And correcting my previous post, there was a mild increase with power-on or decel. It went almost completely away at neutral throttle.