Tim Ashfield

I have fitted 996 17 inch alloys to my '95 Carrera 2.
Before purchasing the wheels I checked that the fit would be OK and every piece of advice was that it would be fine. On fitting the wheels I fitted brand new high gloss wheel nuts the finish extends onto the dome profile (this profile is identical to the originals) that contacts the wheel. My car is in for service, on removing the wheels it is evident that only a very small ring on the domed section contacts the wheel fitting. This is easily seen due to the finish on the wheelnuts. The profile must differ from the 996's wheel bolts. The Porsche specialist servicing the car has not seen these wheels fitted to a 993 before and is concerned at the safety aspects.
Has anyone any info or experience about this issue. Many thanks.

Tim Ashfield

Kim

Thanks for the thread which seems to suggest that some people believe them to be identical and others do not.

This is worrying considering the safety issue. When I get the car back I will be getting a friend of mine who owns a state of the art engineering business to investigate the profiles fully and will post the results.

Tim.

Tim Ashfield

Kim

My thoughts exactly - I will let you know.

Thanks
Tim

cmoss

I'm neieve... Educate me... If one where to mount 996 wheels, why not just use 996 lug nuts?

Are the threads different between the 993/6?

Chris

Tim Ashfield

Kim is correct the 996 uses bolts whilst the 993 uses nuts. The threaded studs that the nuts secure to are splined into the hubs and therefore the only real solution is to use wheelnuts, the only reason this is apparent on my car is because of the new nuts that I have fitted where the finish has extended onto the shoulders. With the original nuts you would not see anything as the shoulders are plain alloy. It is concerning me that people are driving cars with wheelnuts that are potentially insecure. I will post my findings.

Tim.

E. J. - 993 Alumni

I do know one time I was at Sebring in an old car, I forgot the specific wheel nuts I normally use for the track tires. I put on the ones from my street tires and everythig seemed fine until the first turn. Sebring is mostly concrete, so what I tought were the expansion joints were really the wheels vibrating on the bolts as the nuts were not truly tight. Turned into a huge nightmare, but that is a different story. So my story backs up your experience, although my car was not a 911.

E. J.

Jim Michaels

Some of the aftermarket (non-factory) lug nuts do not have the same shoulder shape as the factory lug nuts. My origional alum lug nuts and the factory steel lug nuts have the same shoulder shape, but that shape differs from the shape of a set of aftermarket alum lug nuts I bought from a well-known P-parts distributor. I could tell just by holding them both up beside one another. Now the aftermarket lug nuts may work fine, but I'm afraid to use them. BTW, even with the factory lug nuts, you may not get even force contact all the way across the shoulder because the lug nut seats in the wheels may not be molded very precisely, especially with some aftermarket wheels.

Instead of machining to fit (which may be difficult), why not just torque those suckers down tight enough to *make* the shoulder and the seat fit one another. I'm just kidding; please don't try that at home; you could break something; maybe the torque wrench would be the first to go.

Tim Ashfield

Don't worry I'm not going to bust my torque wrench! But the original and aftermarket shoulders appear identical at least to the naked eye.

Todd

What about factory 996 wheels with 993 part number??
Same thinhg apply?

Tim Ashfield

Can't comment my wheels have the 996 part number.

Tim.

Viken

[quote]Originally posted by Todd:
<strong>What about factory 996 wheels with 993 part number??
Same thinhg apply?</strong><hr></blockquote>

Exactly! Several 993 wheels were used on the 986 and 996 cars. As such, the factory 996 bolts and the factory 993 nuts will work on all the wheels just the same.

Tim Ashfield

Thanx -I have no reason to doubt the info and the answer may well be that the aftermarket nuts are very slightly different (although not to the naked eye) which is worrying in itself. As I have said I am going to get this checked by my engineer friend and will post my findings.

Tim.