XF 300 Sport... minor vibration driving me mad

[StevieBee]

2018. XF 300 Sport estate. 27k miles.

Started to develop a small mild vibration over 40mph but noticeable at lower speeds. Was serviced a couple of weeks ago (Bosch Service Centre) and paid for full diagnostics. Came back with a clean bill of health including wheel balancing.

Got them balanced anyway - and the tracking. Tyres all good

Drives fine otherwise.

It's not a massive thing but is noticeable.

Any ideas? Driving to LeMans next week!

[fatboy b]

Buckled wheel? But it’d surely have been spotted at balancing to vibrate at 40mph.

[StevieBee]

fatboy b said:

Buckled wheel? But it’d surely have been spotted at balancing to vibrate at 40mph.

That was my thinking.

[Simpo Two]

Is the vibration proportional to road speed? Or per gear? Or always the same?

[StevieBee]

Simpo Two said:

Is the vibration proportional to road speed? Or per gear? Or always the same?

Good question.... it's proportional to speed.

[Simpo Two]

StevieBee said:

Good question.... it's proportional to speed.

Must be something to do with the wheels/tyres, brakes or anything after the gearbox, I'd suggest.

I'd go for buckled wheel - courtesy of ECC Highways most likely - or maybe brakes?

Could a buckled wheel pass the balancing test but still cause vibration I wonder? Maybe try the spare, if you have one, in each position and see if it stops it.

[fatboy b]

Simpo Two said:

StevieBee said:

Good question.... it's proportional to speed.

Must be something to do with the wheels/tyres, brakes or anything after the gearbox, I'd suggest.

I'd go for buckled wheel - courtesy of ECC Highways most likely - or maybe brakes?

Could a buckled wheel pass the balancing test but still cause vibration I wonder? Maybe try the spare, if you have one, in each position and see if it stops it.

In my experience - yes. I had a couple of fronts done and I was shocked at the state of one wheel, but it drove smoothly.

[5s Alive]

Simpo Two said:

Maybe try the spare, if you have one, in each position and see if it stops it.

If it does then have a very close look at that tyre. The slightest bulge or distortion in the sidewall can cause vibration, without steering wobble even if it's on the front. Had this on my daughter's car and it was a barely distinguishable bulge on the inner sidewall.

[remedy]

fatboy b said:

Simpo Two said:

StevieBee said:

Good question.... it's proportional to speed.

Must be something to do with the wheels/tyres, brakes or anything after the gearbox, I'd suggest.

I'd go for buckled wheel - courtesy of ECC Highways most likely - or maybe brakes?

Could a buckled wheel pass the balancing test but still cause vibration I wonder? Maybe try the spare, if you have one, in each position and see if it stops it.

In my experience - yes. I had a couple of fronts done and I was shocked at the state of one wheel, but it drove smoothly.

Indeed. I had new front tyres put on my XKR and the fitter called me over to show me the buckle on 1 wheel. Looks like it hit a big hole or kerb at some point. But it's never lost pressure. I will get it repaired at some point.
I thought it was the cause of the judder I got on initial braking. They balanced the wheels without issue and I later found out the judder is normal on an auto because of the discs slightly warping when sat on the brakes, after heavy braking.