Shuddering on light acceleration

AusVolvo

Hi guys, I hope someone might be able to give me some guidance, my 2009 XC60 has a shudder on light to medium acceleration, it can be quiet violent and shake the whole car and is worse going uphill.
The shudder mainly appears when in 3rd gear between 20 & 50 kph but sometimes starts just before it changes from 2nd gear.
I initially diagnosed it as front CV shafts as I was aware they were becoming worn so I ordered a set of new "Original Performance" shafts from Nashville in the US which I have installed, the shudder has improved slightly but is still there.
If I accelerate harder it reduces the shudder, if I reduce acceleration it becomes less obvious.
Is there a common problem with these when using aftermarket shafts? It still seems to me to be a CV joint frequency, it doesn't feel like a rear tail shaft uni joint type vibration as this is generally a higher frequency, the only other things I can think of might be engine/transmission mounts, I've checked the engine movement when parked and it seems quiet normal & not excessive. I'm a motor mechanic but have been out of the game for many years so may have lost most of my diagnosis skills.
I have read on another forum about the XC70 being very fussy with CV shafts if they were non genuine, could this be the case with the XC60's as well?
Thank you for any guidance and all input is appreciated.

timbo

The T6 motors chew through the engine torque mount. It's the dogbone shaped one on the Rh side of the engine bay that sits above the engine mount. It will give an audible harmonic vibration. It's worth checking it shouldn't have any free play on the front bush. If you can move it with your hand it's fkd.

AusVolvo

Thanks Tim, Ill check it out, the engine has very little movement but its worth a closer look, cheers :-)

AusVolvo

I've checked both the top and the lower engine torque mounts, they are both good with no movement or cracks in the rubbers, I did not however that the LH inner CV joint has some play when I rotate the wheel eg. i rotate the wheel forward and backwards a couple millimeters & the inner shaft does not move, this is only a couple of millimeters of tyre movement, the outer shaft has no play, neither do the RH joints.
I spoke to another mechanic & he suggested that if it was the CV joints it would be there all the time but with my old XC70 the joints were buggered & it only appeared on light acceleration or when the vehicle was turned sharply & heavy acceleration. I also spoke with a transmission specialist who said they do a lot of the valve bodies on these due to shudder but he said the shudder is generally there all the time including at high speed.

shlowsby

Hi, @AusVolvo I know it's been a long time since you reported the issue, do you remember what the cause turned out to be?

I'm experiencing a similar problem on my XC90 with the same AW TF-80SC transmission. The vehicle vibrates around 1500 - 2000 RPM when under load, with the vibration most keen in 3rd gear. It disappears at higher revs.

I've tried replacing bevel gear oil and transmission fluid, and removed the Haldex fuse to isolate the problem, but the vibration persists.

Prontel

shlowsby Did you manage to solve the problem?