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Wheel Offsets - Torana & Commodore

Started by _jklumpp_ , Aug 24 2009 04:17 PM

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11 replies to this topic

#1 _jklumpp_

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Posted 24 August 2009 - 04:17 PM

Can anyone help me out with the offsets for both LJ & commodore wheels.
I am trying to work out the diff width needed to run Commodore rims & diff in an LJ... any help appreciated
will likely be running 15x7 rims - 205/50/15 tyres....

Cheers,

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#2 _jklumpp_

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Posted 25 August 2009 - 09:48 PM

Anyone?
From what I can find, +38 seems to be a common number refered to as Commodore offset...

Does a 'P' number represent offset? ie. my sprintmasters have 18p cast in them - does this mean +18mm offset?
I measured from the mounting face to the rear rim lip as 108mm on my sprintmasters. The wheel/tyre size calculator link suggest that an 18'ET' offset would be 106mm face to lip (backspace)... so seems close?

So if this is all correct, the dif would need to be 20mm wider each side to keep the same track?

Surely someone on here know this stuff?

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#3 _evil UC hatch_

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Posted 25 August 2009 - 10:38 PM

Chopper crunched the numbers for me a while ago for a similar comparison, and that was about the answer I got from memory.

going from the standard torana offset to the details I supplied of the 16x8 wheels I have. I came to the conclusion that with using the skyline borgwarner as I plan too the difference will be minimal without changing the diff length.

I cant remember the full details though but the info is here somewhere....

I will see if I can find it, but might be tough

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#4 ls2lxhatch

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Posted 25 August 2009 - 10:52 PM

It would be safer to measure the actual Commodore rim you intend to fit. I would not be surprised if you find small variations in the offset from one rim manufacturer/style to another.

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#5 _evil UC hatch_

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Posted 25 August 2009 - 11:04 PM

here is that thread I mantioned, note that the info was given using the difference in diff width with the skyline borg warner and my particular wheels, borgy is 10mm wider

http://www.gmh-toran...ic=14036&st=125

difference between the two diff, borgy/bango measurements are on the first page I believe

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#6 Growla

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Posted 25 August 2009 - 11:21 PM

P18 refer to the offset of the center of the rim.

So yes a p38 will need 20mm more width in the diff per side to keep the same track.

However the backspace is the distance of the hub mounting face to the edge of the rim.
so a p18 offset on a 7" rim will have a different backspace to p18 8" rim.

Offset calculator

The link may help you.

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#7 _jklumpp_

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Posted 26 August 2009 - 11:15 AM

Thanks Guys,
yes Growla, that was the web-site I was using... So a 18p it eh same as what that web-site refers to as ET18...

So I know the off set of the Sprintmasters - can anyone varify the offset of Commodore?

Thanks for the link Evil - Syline diff is about 100mm wider than LJ, so I would still have to have it shortened....

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#8 _evil UC hatch_

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Posted 26 August 2009 - 11:21 AM

I think there can be a little varyiation on the offset of the commodore wheels, do you have some you plan to use or are you looking for the most common to use as a reference? I dunno what the offsets usually are anyway, but surely someone does

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#9 ls2lxhatch

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Posted 26 August 2009 - 11:40 AM

The Commodore factory rim offsets and center bore diameters vary considerably throughout the range. Aftermarket rims will also vary again.

To build a diff without deciding on and measuring the rims first is asking for trouble.

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#10 _jklumpp_

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Posted 27 August 2009 - 08:30 AM

Yeah, I hear ya LS2... I think I will keep the banjo running until I have all the bits sorted, then tackle the whole thing at once...

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#11 _CHOPPER_

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Posted 28 August 2009 - 12:37 PM

18P is the same as ET18. Most Commodore rims are +43, but some range from +27 to +48 depending on model. Commodore centre bores are 69.5mm for VB-VZ commodores. VE is apparently 66.9mm. 4 cly Commodores used 13x5.5" Torana rims. 13x4.5" Torana rims are +19 while 13x5.5" Torana rims are +32. By rights, the factory optional 13x6" Torana rims should be +25.

Hope this helps.

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#12 _jklumpp_

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Posted 29 August 2009 - 07:39 PM

Thanks Chopper, that's what I was looking for.
Strange thing though - I just bought some Commodore Simmons, and the seller has said the backspace is 120mm - which I work out to be around ET18 on a 15x7 rim?... doesn't seem to add up.... will have to wait & see when the rims arrive...