Highway speed vibrations. 15 V70 FWD

[MartinKa]

Hi guys,

I've been battling a slight vibration in my FWD P3 V70 for a few months now. Vibrations start at highway speeds 50+mph and get worse with increased speed. Its never real bad but it can be felt through the steering wheel and seats. The one weird thing about it is seems to come and go when cruising at a constant speed, at least it feels like it.

Things I've done:
Front lower control arms.
Alignment
All new engine mounts
Tried 3 sets of wheels
Checked bearings, struts and all front end ball joints.

Two sets of the wheels act the same, thus I believe they are okay. I've not had them road force balanced but they are spot on on a normal balancing machine. Ball joints feel tighter than most aftermarket joints i've used, no play can be felt in the wheels. Bearings and brakes are good, no pulsing under braking. Struts are a bit tired as the car has around 200k miles on it, but they do work and move smoothly.

Changing engine mounts helped reduce a bit of the vibrations. Before vibrations used to be very noticeable in the seats, after changing its a lot better but still some remained. Putting it in N during driving does nothing, vibrations remain exactly the same.

Can a worn CV cause my issues? They are original at 200k and a bit of rotational play can be felt in the inner joints. (Very little, but visible)

I'm hoping somebody has had a similar issue and can give me pointers what to check next.

[scot850]

Have you checked intermediate bearing on the RH axle for wear? What about the inner and out tie-rods, and as you are feeling the vibrations through the seat, have you checked the rear suspension for worn bushes?

Neil.

[MartinKa]

Have you checked intermediate bearing on the RH axle for wear? What about the inner and out tie-rods, and as you are feeling the vibrations through the seat, have you checked the rear suspension for worn bushes?

Neil.

The intermediate bearing has been on my mind a few times but i have not taken it apart enough to really feel it yet. Inner and outer tie-rods are tight. The rear suspension is a definite possibility though. I did check the rear with a crowbar and while some bushes are old looking they still felt okay. But.. I'd say most of it is original to the car..aka 200k miles old.

[scot850]

At that mileage the rear suspension, if original, is probably needing some love. I am about to get organizing for a refresh on an 02 XC70 which has 250,000 miles on it. Some of the bushes look ok, but we know there is an issue as the rear tires are wearing strangely.

Neil.