Mk 1 Octavia VRs terrible vibration

[paolow]

Can anyone suggest a cause?

I have a Mk1 Octavia VRs hatch that has an odd problem.

First noticed about a year ago - at motorway speeds it made a 'thrumming' sound - bit like when you live in a flat and upstairs has a washing machine on a spin cycle. ie - distant but an 'unbalanced high speed sound'
Fast forward 6 months and, on a long (12 hr) road trip it became evident, but still not a problem that after a time of high speed / low speed driving a more pronounced 'thrumming' but also a lower frequency shaking of the car. It was almost as though one of the tyres had a 10mm x 10mm 'egg' coming out of it that would shake the whole car as it rotated. (ive looked and cant SEE anything - but I am not a road....) The tyres seem fine to me and I have had a new pair of fronts (hankooks) that have had no affect whatsoever on the effect since. The odd thing was that this is quite forceful after a run whereas during 'short commute driving' the car is perfect.
Fast forward to today where a spirited and private 'lepton plus' burst literally had the whole car shaking.
Something is the matter - but I do not want to give the car to a garage and have them indiscriminately change parts
My thoughts are:
its been getting progressively worse
it gets worse the greater the road speed, though is still evident at low speeds at lower frequency.
it can't be the tyres - was evident before and after the tyres
Only FRONT tyres - mind.
it MUST be something in the drivetrain
my engine works fine - I Dont THINK that is the problem
The steering wheel is 100% smooth even when the car is shaking..In fact - it is dead smooth - so it seems perfectly balanced.

[SWR Performance]

Driveshaft joint about to die, I would guess... don't know the proper term in English, as it's not my regular language..

[Pumaracing]

Yes it's a driveshaft. Wheel and tyre balance problems mainly manifest at a specific speed where the resonant frequency of the wheel rotation matches that of the suspension. Driveshafts manifest over a much wider speed range and are worst during hard acceleration and deceleration.

You might find a torn rubber boot on one side but if not the play in the joint will tell you which side is failing. Best to get it fixed before it breaks and you end up in a hedge.

[paolow]

Thanks guys. I did consider a driveshaft / driveshaft joint but it doesn't grumble at all on full lock etc. That said - I appreciate there is more to a driveshaft than a CV joint!
Its only done 60k - though it is 8 years old so it will be more town driving than not which won't have helped.
Amazing really that it can have such an effect on the car - though as its been 'going' for a while so I'd better get round to addressing it!

[Simon says]

Also agree with above but ..... make sure the drive-shaft damper (if fitted) as not broken away from its fitted position an flaying up and down the drive-shaft when its spinning, its an easy visual check this one while your up there give the wheels a spin in the straight ahead position and make sure the shafts are running true (no bobbing up and down) then move onto the inner and outer CV joints