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Hello people, could I please pick your brains on this...

At 70,000kms, my 2010 NC2 AT is scheduled to be in the dealership tomorrow for them to hunt down the cause of a rather mild steering wheel vibration. It is not akin to steering feedback or the right-left-right movement one would associate with out of balance tyres. Started noticing it about a month ago when tyre noises started. Dealership said my tyres were scalloped. No worries had all four tyres replaced and the noise went away. Also replaced stock suspension to coilovers since the ride was becoming bouncy and body roll was getting too excessive for my liking. My wheels have passed the tyre fitter's test prior to balancing, so no bent rims anywhere according to him, and an alignment has also been done. And oh, wheel lugs nuts are presently torqued to 100Nm.

The vibration has remained since. As I said, it's not severe, but enough to annoy and suck out one's confidence when driving. I note as well that the steering wheel and cabin vibrates slightly while idle at 'D' - it has been rock solid prior. Could this be a sign of worn engine mounts, and if so - could worn engine mounts cause steering vibration while on the move?

I will be asking the dealership to conduct a thorough inspection on the following:

- engine mounts
- tie rods
- ball joints
- control arms
- steering column/steering shaft
- wheel bearings
- wheel hub / wheel centric-ness

As a last resort if the above all pass their test - I will ask them to move the front tyres to the back and see if it could indeed be a faulty rim.

What in your opinion could be causing this issue?

Standard wheels?
What tyre pressure are you using?
What brand, model and size of tyre is currently fitted?

Standard wheels , 32F/31R, new Kumho 205/45/17 KU39s...

Hmmm...weird.
You shouldn't have any suspension issues at 70,000km unless it has been damaged.
I doubt engine mounts but there could be some other drive train issue.
Mine has no problems at 87,000km including track time so I'm at a loss.

no one can tell you but most vibrations in steering come from wheels / tyres. Mechanics normally want to experience the fault.

Well...I got my ride back last night with front wheels swapped to the back and torqued to my preferred 100Nm. It appears that 90% of the vibration - mild as it was - is gone, with the remaining 10% being what I would attribute to mainly feeling a lot more with the relatively new coilovers. But most of it now is just standard steering response. Felt even better this morning while going through a familiar rough patch, the steering felt planted instead of twitching. Feels like it's no longer the pits (an exaggeration of course - I'm just anal) driving the thing and most important of all my confidence has come back!

So it appears there is perhaps a slight anomaly with one of the rear wheels. The tyre fitter did mention that one of them had a "heavy spot"; with one requiring more balancing weights than the other. With non-directional tyres and a rather aggressive negative camber I can fortunately leave the wheels where they are and remount the tyres each time a cross rotation is done.

Now to sit back and hope the issue never returns, and look forward to my new FSTB arriving!