vibration/shudder problem @ high revs VZ Calais

[goodday]

Hello guys

I have a 05 VZ Calais 5.7lt auto with 95000 kms on the clock. Well, I’m actually based in Dubai so it called a Chevrolet Lumina. Royale here.
Today out of the blue without prior problems I have a big shutter/vibration coming from what feels like the back of the car. Could also be coming from the transmission. It starts in the higher rev range between 3000+. It gets much worse the harder you put the foot down. It does this up to about 90kmph. Between 100 and 160 it’s smooth again no matter how hard you put the foot down. I’m not completely sure where it’s coming from, maybe the diff or somewhere in the drive line.

Does anyone have an idea as to what this might be. I’d simply take it to the dealer but the clowns here will take all your money if you have no idea yourself. I’d like to take it to them knowing a bit about what the problem is.

Any help would be much appreciated.
Regards
George

[Calaber]

From your description, it could be a couple of things.

The tailshaft is a two piece design, with a constant velocity joint mid-way, mounted in a rubber ring. This rubber can break down, allowing the tail-shaft to run off centre, creating a shudder through the car.

The second problem is the rear universal joint - I think it is actually a rubber ring on VZ's. This can also deteriorate, allowing the tailshaft to vibrate badly.

Jack the car up, slide under and check the tail shaft for sideways movement at the centre bearing. There should be very little. Push sideways and up and down towards the floor. If the rubber mounting is damaged, you might be able to see the damage.

The rear uni joint will be pretty obvious - you can see the damage if that is the problem, but try grabbing either side of the joint and twisting in opposite directions. You shouldn't be able to twist it at all.