Hi.

I've got an 09 XF with the supercharged 4.2 V8, and though I'm very happy with it, I have a growing concern about some vibration I've experienced 3-4 times now.

First time I noticed was going out of a parking garage, where there's a sharp right after the gate. To check the sound in the garage (it sounded like this: WROOOOOM) I floored it, but when I started turning there was an awful vibration in the car, I felt it very strongly in the steering wheel.

I stopped and checked every wheel bolt and they were all firmly in place, so at least the wheels weren't coming off.

I park at this garage regularly, and I tested the same turn later without going as fast, and there's nothing, all smooth.

I then recreated it by going fast again at the same place with vibration, and I thought "oh well, probably something with the tarmac or something, I'll just have to go slow here".

However, this afternoon when I went a bit fast to catch a yellow light with a right turn right after, I had the same uncomfortable vibration while breaking and going right. This is the third last turn before I come to my house, so I drive here regularly, and this is the only time I've experienced it.

So, my (possibly ignorant) thoughts so far.

It always involves:
- Speed, either accelerating or breaking relatively hard.
- Going right.

I only noticed it after changing to winter tires, though I can obviously go much faster on the open road than inside a parking house (at least if I want to park there again), and that's been all fine except this afternoon's experience.

I'll take it to a tire shop on Monday and have them check all four wheels, but I suspect it'd be more of a problem if it were the tires.

Any thoughts? Any similar experiences?

 

Could be slipping so the transaction control is kicking in? Accelerating when the wheels are turned often induce skidding. Just a thought.

 

I agree ^^

 

Hmmm, that might be possible. I guess I need to find a big parking lot and test going left and right and see if I get the same result, and then switch of the traction control and see how it behaves then.

 

Traction control does apply a rear brake to the inside wheel if you step on it in sharp turns. Seems more common in right turns. Not much extra gas is required to trigger this in sharp turns because the relative wheel speed is high due to the turning radius.

 

And the result is a semi-violent vibration? But now that I think about it, it is somehow similar to the traction control I've been used to front wheel driven cars...

Will find someplace safe and test it tomorrow, local time is almost 3 am here now, not sure if it's a good idea to go do it at this hour. :P

 

Well, the brake application is a vibration as it is applied and released rapidly as for ABS operation. The violence may be subjective or may be related to the traction actually available. On low traction surfaces the vibration is very mild.