hub question - centre bore........

[SeventyNine]

righty, so i made a blunder with my hubs......and being a second year automotive engineering student i should really know this but.

my audi wheels are 57.1, i've had the hubs machined down to 57.1 and they don't fit, from what i can measure with my trusty woolworths ruler is that they are a little bigger than 57.1.

so, what do i ask my good friend to hactually machine them down to? considering 57.1 - 57.1 is an interference fit.......

[kee]

as far as I'm aware, as long as it fits over it shouldn't matter really. i am quite probably wrong.
presumably the weight of the car will be on the bolts non?
in which case, shave a mil off and i would imagine that would be ok!

wait for someone with a bit more knowledge to answer before you set out and get the re-machined ;D

[SeventyNine]

ok ;D

wheel studs/nuts are in tension which takes the shear force acting on the wheel, the centre bore carries the wieght of the car and any vertical forces actingin on it (in shear)

I know the theory but I have no idea as to how big I should make them

[arthurbrown]

Can you have the hubs & wheels in the machine shop & work by trial & error till they slide on snugly but you don't have to force them.
Chasing off 1mm at a time might be too much you see.

[Lewis]

Dip the hubs in liquid nitrogen and refit.

Sorted.

[gotwood]

When I usually make hub spacers/adaptors I make the the spigot to an outer diameter of exactly 57mm . This gives a nice fit with no slack .

[slater]

the idea is the wheel i/d is 57.1mm to fit over the 57mm spigot on the hub

For all it matters you could just take a bit off with a file.

[SeventyNine]

thanks for that you guys, i was gonna take them down to 57 but thought i'd ask first.

i can't be bothered to file them down, its easier to take them to uni and ask my pal to wizz them round

[kee]

Ah i see.

so would wheels with a bigger centre bore cause trouble then?

[slater]

Nope not relly.

[Odin]

Is the centre bore fit on the spigot that important? I thought the friction against the hub caused by the bolts being tightened was the load-bearing bit, and the spigot just helps with alignment when fitting.

I'm rolling too-large centre bores at the moment and have noticed a slight wobble tbh. :-\

[slater]

yeh basicly the spigot is just for alignment.

You will find it is quite useful if your using wobble bolts or big spacers (maybe even sleeve nuts) but other then that its pointless.

[SeventyNine]

wheel nuts are loaded in tension, not shear. its the centre bore that takes the vertical loads.

a bolt has no shank, therefore it should take no shear force at all.

[Adam]

Apr 20, 2008 18:01:28 GMT SeventyNine said:

wheel nuts are loaded in tension, not shear. its the centre bore that takes the vertical loads.

a bolt has no shank, therefore it should take no shear force at all.

The friction take the vertical load. The centre bore shouldn't take any weight unless you don't do your nuts/bolts up tight enough!

[Team Blitz]

Apr 20, 2008 18:01:28 GMT SeventyNine said:

wheel nuts are loaded in tension, not shear. its the centre bore that takes the vertical loads.

a bolt has no shank, therefore it should take no shear force at all.

If that was true, then all those cars out there with OE wheels fitted to their smooth slab-sided hubs (with no centering external hub nubs) would have wheels falling off in the parking lot.

See every Capri Mk1 using the German Atlas dif, for example. There is no "hub" for rear wheel fitment. The studs center it. The studs take all the shear. Back to school with you, then, young man.

[slater]

Indeed. Think of it the same as a keyway on a shaft and pully. Lots of people mis-interprate the keyway as 'driving' the pully but in reality its there to align the 2 parts, if the pully was to come loose it would muller the keyway/key in no time at all.