Machining wheel mating surfaces to change offset?

[Cloudsurfer]

So heres one for the smart, engineering types:

Is it possible for a good machine shop to re-machine the mating surfaces of a wheel to increase the offset? I have turbo twist hollow spokes on my car (18x10 ET40) that I would love to take to about ET45, so it possible for a shop to take off 5mm of the mating surface to achieve this?

I realize this would have to be done with extreme precision, but I'm inclined to think its possible since the machining of those surfaces are the last step performed in normal wheel manufacturing, and a shop that can precisely deck cylinder heads I would think could perform this properly.

Any input on this would be greatly appreciated.

Patrick

[MNBoxster]

Hi,

You do not want to remove any material from the wheels...

Happy Motoring!... Jim'99

[Rodger]

Normally a shop would use a vertical mill with an endmill bit to resurface a head. They run the bit back and forth across the head until it's level. It's crucial to ensure the head is properly leveled prior to starting the milling, to ensure the head is milled evenly.

With a wheel, I'm sure the preferred method would be to install the wheel on a lathe, then move in with a cutting bit at the center of the wheel, then bring the bit outward to remove the necessary amount of material. This would probably be done in several small cuts.

They're two completely different processes, but any machine shop (automotive o otherwise) with a large lathe can do the job.

[Cloudsurfer]

Jim-

I fully realize that this is probably not Kosher as far as Porsche is concerned, but I dont see why, if dont correctly, this would cause any concern for failure.

The real concern as far as I see it, is ensuring that the wheel's centerline is aligned perfectly parallel to the lathe so that, once milled, the mating surface is still parallel to the wheel centerline to avoid shimmies and vibration, etc.

Patrick

[MNBoxster]

Hi,

It can be done and on a Lathe, not a center pass machine. But, you're going to significantly weaken the wheel at it's main attachment point, not adviseable...

Happy Motoring!... Jim'99

[Cloudsurfer]

Jim-

I thought about the potential weakening to the wheel center, however (and please do correct me if I am wrong), the center hub area is solid alloy, as its where the lug bolts go through, so taking off a few mm of material shouldnt have a profound effect on the overall integrity of the wheel as a unit, or am I completely off base with my thinking?

Patrick