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Centre spigot sizes for wheels and locating rings [anybody use them]


Atinod

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For my S3 de Dion [with 4 x 4.25" PCD all round], it appears that the front centre spigot size is 58mm diameter and the rear de Dion 64mm.

 

Does anybody worry about getting these right when ordering new wheels [for the Compomotive bulk buy actually] or using locating rings, or does everybody just let all the load go on the studs *confused*

 

Edited by - atinod on 12 May 2008 10:36:56

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I was shocked by this when I first got my 7, and enquired of CC who said it's perfectly OK to locate via the studs.

Personally I think it's not ideal, but you have no choice.

 

MY BLAT-O-METER

2008: 32 (to 12th May)

2007: 70

2006: 89

2005: 91

2004: 64

2003: 66

2002: 66

2001: 79

2000: 32 (divorce!)

1999: NRA

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I had a BMW 525TDS which had those daft metric wheels. When I swapped to a set of std wheels, I couldn't get the d*mn things to fit square (or round if you get my drift) and the balance was way out, as the spigot size was off by a couple of mm. The local garage fitted a set made of polypropylene (iirc) which fixed the problem. I'll ask where they got them from.

 

Alex McDonald

PASSED THE MOT!!!

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Hubcentric wheels fit on the hub spigot to ensure concentricity.

Tapered wheel bolts or nuts will only seat when the bolt holes are concentric with the bolt/stud centres.

Unless the two are very accurately machined, then the wheel and the studs etc must deform within the modulus of elasticity, until they achieve contact

So why would we need spigot rings with tapered bolts/nuts.

I ask. 🤔

 

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This has been of some concern to me lately as I have 3 sets of wheels (Ford PCD) that are all completely different re. centre hole size.

 

In theory, locating rings should always be used to transfer the cornering loads directly to the hub not the studs. The studs are there to hold the wheel onto the hub shoulder (tensile force) not take the shear forces that occur in cornering.

 

That said in a car as light as a caterham the forces will be considerably less than a car 3 times its weight. As I don't know the age of the studs on my car (and coupled with the fact that the front ones are a bit too short for my liking) I shall be replacing them just in case - maybe worth considering if your worried about it.

 

Regards *wavey*,

 

Giles

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Yes,

The studs should only be in tensile stress. But by not being wobbly; ie with spherical section nuts and bolt heads, they are being forced sideways to a degree dependant on their fitting accuracy.

But with a car as light as a Caterham, they shouldn't be overstressed. Ought to back that last up with some calculations, I suppose. *rolleyes*

 

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