Took the driveshaft to a couple of rebuild shops today. Spun it on the balancers, heard plenty of knocking, took videos and sent them to the warranty company. Will hear back tomorrow.

Took a couple of pics of the slipjoint and driveshaft behind the slipjoint.

Noticed the absence of any lubricant and the blackened areas on the spline...



...and the lack of any seal or old grease between the joint and rest of the shaft. Is that normal for Jags?



Thanks!

 

So we lubed the slipjoint today and put it back in the car at the request of the warranty company. We ran the car on the lift at about 40-70mph and the buzz and some knocking were still there but diminished.

I took it out on the road and the noise was diminished by about 60-70%, which was a lot better than I expected. Only heard it a few times when reducing throttle. Looks like it is the slipjoint, now it's a question whether the grease will keep it bearable or whether it returns in full force.

 

Is that knocking at a particular rpm range? I'm getting some buzzing that is coming from the rear of the car but only happens around 1900 rpm. It seems like a resonance that only comes out around 1900 and more than a light throttle.

 

Yes, that's exactly the range it's occuring in. Cruising around town at about 40mph, and it buzzes with small throttle movements to maintain that speed up and down hills.

The driveshaft is an empty tube behind the slipjoint, so it can easily transmit the sounds from the joint to the end of the shaft.