[Baffler]

Hey Martin,

I know it's a different beast but had a similar issue when breaking with my S80 back in 2019. Replaced the following:

Disks and pads front and rear (ATE).
Front bottom ball joints (Lemförder).
Front wheel bearings (SKF).
NS driveshaft (J&R).

Front control arm bushes were in very good condition with little travel.

All four brake calipers traveling nice and free.

No noticeable play in the inner tie rods or outer track rods.

Vibration still there. Swapped the front brake disks around...still there. Baffled!

Had my tyre chap balance all four wheels, fit the fronts to the rear and vice versa. Still present but vastly improved after balancing. You may wish to consider this if not already done so.

Whilst there I asked him to carry out a four wheel laser alignment and, with the car in the air, we discovered some play (gear lash) in the steering rack. I brought the car home and managed to get some adjustment on the rack and pinion. Sorted!

Not sure if the 900 has this rack adjustment but just thought I'd share my experience.