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Old Jun 12, 2018 | 09:23 AM
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Default centre bore question

Is the correct centre bore for a C3 70.3? Im looking at a set of spacers and the seller said they are 70.3 centre bore with a wheel centering lip.
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Old Jun 12, 2018 | 09:35 AM
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No, it’s 70.6 for C3’s. Newer GM’s are 70.3.

Last edited by 69autoXr; Jun 12, 2018 at 02:30 PM. Reason: .
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Old Jun 12, 2018 | 09:41 AM
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Thanks!
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Old Jun 12, 2018 | 02:06 PM
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Old Jun 12, 2018 | 02:20 PM
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Hmmm seems like there’s not much selection online for 70.6 centre bore spacers
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Old Jun 12, 2018 | 02:30 PM
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go to motorsport-tech.com and you can order exactly what you need
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Old Jun 12, 2018 | 03:13 PM
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Default Go with the best. Dorman !


I keed I keed. These are mock up units only.


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Old Jun 12, 2018 | 04:11 PM
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Originally Posted by 69autoXr
go to motorsport-tech.com and you can order exactly what you need
thanks. I sent them an email with my request
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Old Jun 13, 2018 | 02:04 PM
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That place quoted me $325 for the set, a lot more than I expected for a set of spacers.

Would the attached ones work just as well?


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Old Jun 13, 2018 | 02:37 PM
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Sounds like you're looking for adapters rather than spacers. The bore on those above is too tight, you'd have ~0.002" interference at the radius. I'm not a machinist but I don't think you'd ever get it to go on.

edit: I think for a press fit you'd be looking for ~0.0005" interference across the diameter, this is approximately eight times that interference across the diameter.

Last edited by 69autoXr; Jun 13, 2018 at 02:47 PM.
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Old Jun 13, 2018 | 02:38 PM
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I don’t want adapters. I just need spacers to push the wheels out more since they have 6” backspace
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Old Jun 13, 2018 | 02:53 PM
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Ok, I was going from the photo you posted which appear to be adapters (1" thick with pressed-in studs).

How big a spacer do you want? I had motorsport-tech make me 10mm hub and wheel centric spacers and they charged me $70 for the pair in 2012.
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Old Jun 13, 2018 | 02:56 PM
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I’m looking to get 3” in the rear and 1.5” in the front. The wheels I’m getting are 18x10.5 with +25 offset and 6.34” backspace.

I need some beefy spacers to get them far out enough to fill up the L88 rally flares
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Old Jun 13, 2018 | 03:07 PM
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Originally Posted by titanle
I’m looking to get 3” in the rear and 1.5” in the front. The wheels I’m getting are 18x10.5 with +25 offset and 6.34” backspace.

I need some beefy spacers to get them far out enough to fill up the L88 rally flares
You need adapters to get that kind of thickness. Bolt adapters to the hub, bolt the wheels to the adapters.

Maybe check the classified ads to see if anyone has something similar for sale.

Can't you get wheels in your size that are closer to or have the correct backspace?

Last edited by 69autoXr; Jun 13, 2018 at 03:08 PM.
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Old Jun 13, 2018 | 03:11 PM
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Sorry I got confused for a moment. Spacers have holes for the existing studs and they just push out the wheel a little

adapters have a new set of studs which the wheels would bolt to and the adapter would mount to the car.

so yes I would need adapters. Any place to get them at a decent price?
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Old Jun 13, 2018 | 03:16 PM
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Originally Posted by titanle
Sorry I got confused for a moment. Spacers have holes for the existing studs and they just push out the wheel a little

adapters have a new set of studs which the wheels would bolt to and the adapter would mount to the car.

so yes I would need adapters. Any place to get them at a decent price?
Not that I know of, I haven't looked at buying adapters in almost 20 years. I bought mine at VBP but I don't think they carry them anymore, and they were probably in the $300-400 range at that time for a set of four.

Last edited by 69autoXr; Jun 13, 2018 at 03:16 PM.
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Old Jun 13, 2018 | 03:29 PM
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They’re selling for the same price now. But in the long run I think it will work out cheaper than getting a set of 12” wide wheels and paying for 3xx wide tires
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