Increasing negative offset in wheels
03-08-2006, 09:59 PM
#16
I was comparing a 951 CS 8 inch rim Adam B bought a while back ..it had a factory offset of 52mm. When I put the 8" CS rim from my GT next to it (factory offset of 60mm) it was obvious that the inner face was machined down to 60..so I appears Porsche milled 8mm off the forged 52mm 8 inch CS rim to make the 60mm offset 928 CS rim....I haven't looked at my other set of CS rims to see if they are different..but don't think they are...
later,
Tom
89T
later,
Tom
89T
Originally Posted by cfc928gt
Yes, the face can often be safely machined down some. I have a wheel guy with 25 years in the business who did that on one of my sets. He machined off about 4 -5 mm. Any more than that and you need to reinforce the holes.
03-08-2006, 10:09 PM
#18
Captain Obvious
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Originally Posted by FlyingDog
Tom, Is the thickness from the hub face to the bottom of the lug hole the same or different?
Liek I said before, the hub face gets machined first, then the lug holes are drilled to a specific depth.Now if one could buy a set of rims that don't have the hub face and holes machined yet (only the pilot holes for the lugs are needed), they could make whatever offset they desire.
03-29-2006, 09:38 PM
#19
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Originally Posted by Imo000
I believe they have one mould for various offsets. The problem is not how thick the “hub” part of the rim is but rather how deep the stud holes go. I think they machine the offset of the rim first, then they drill the stud holes. These holes will determine how thick the mounting material will be on a rim. Once the holes are drilled there is only so much material left to do any additional machining.
03-29-2006, 10:15 PM
#20
Captain Obvious
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Originally Posted by Hacker-Pschorr
FWIW - I just measured the stud holes on the 2005 997 18" wheels I bought. On the rear wheels 10x18 et58 the stud hole is just under 1/2 inch.
03-29-2006, 10:31 PM
#21
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Originally Posted by Imo000
You mean the distance between the mounting surface and the bottom of the hole is 1/2"?
03-29-2006, 10:40 PM
#22
Captain Obvious
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Wow, that's not much and that's factory spec, right?
This makes me think about the other tread where the mounting surface was machined and ~5mm (~1/4") was removed.
This makes me think about the other tread where the mounting surface was machined and ~5mm (~1/4") was removed.
03-29-2006, 10:42 PM
#23
Three Wheelin'
Between the 997 and the Cayman, we have some nice wheels to chose from in 928 land. 18's and 19's. Both of those cars have ET 57 fronts vs ET 60 on the 8 inch CS front wheel. The rears either fit or can be spaced out. Plus, they are getting cheaper on ebay as time goes by.
Oh yeah. And no machining required.
Oh yeah. And no machining required.
03-29-2006, 10:45 PM
#24
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Originally Posted by Imo000
Wow, that's not much and that's factory spec, right?
This makes me think about the other tread where the mounting surface was machined and ~5mm (~1/4") was removed.
This makes me think about the other tread where the mounting surface was machined and ~5mm (~1/4") was removed.
I just measured the fronts - same as the back, just under a 1/2"
Yes these wheels are getting damn cheap. There are 2 sets of 19" 997 wheels with a friendly 928 offset for $1,100 on ebay right now.
