RazMan
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| posted on 4/9/07 at 06:00 PM |
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quote:
Originally posted by daviep
Okay so far nobody has explained how slotted spacers can cause a wheel stud to shear!
Ahem!
quote:
Originally posted by RazMan
The extra support from the hub ensures that you get the wheel absolutely central (ensuring good wheel balance) and also takes the shear forces away
from the studs.
[Edited on 4-9-07 by RazMan]
Cheers,
Raz
When thinking outside the box doesn't work any more, it's time to build a new box
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ChrisGamlin
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| posted on 4/9/07 at 08:17 PM |
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quote:
Originally posted by Avoneer
It's not about asthetics - my wheels & tyres are damn close to the bolts holding the trailing arms, as I found out on Saturday at
Elvington.
Pat...
Hi Pat
I had the same issue with my book rear end with the wheels I had, so used the cheapy 5mm spacers on each side for loads of trackdays without any
issue, but a properly fitting / machined set would be better obviously.
The alternative (as Ive accidentally found) is if you have split rims, make them an inch wider on the outers only. Having rebuilt my Compomotives to a
7.5" rim on the back, the (205-60-13) tyre is held more stable by the wider rim and central to the (now wider and more outboard) rim so rolls
less under cornering, meaningvno clearance issues without spacers, despite using exactly the same rubber.
What about using M12 (or 1/2" whatever you're using) button head bolts if they are shallower than a conventional bolt head? You can get
them in fairly high tensile strength and its all in double shear anyway with no force other than the clamping force on the bolt head, so the
comparative lack of meat on the head won't be an issue.
Chris
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Avoneer
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| posted on 4/9/07 at 09:00 PM |
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Chris - did you get some "rubbage" from the front bolts that hold the trailing arms?
If so, that would make me feel a whole lot better knowing it was more of a design floor than something i've done or used.
Pat...
No trees were killed in the sending of this message.
However a large number of electrons were terribly inconvenienced.
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ChrisGamlin
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| posted on 4/9/07 at 09:03 PM |
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Yep I managed to "polish" the front bolts which are right in line with the edge of a 205/60 13 tyre on mine. With a 185 I didnt have an
issue because the tyre wasnt quite wide and big enough to touch them when flexing.
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daviep
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| posted on 4/9/07 at 09:12 PM |
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Wheel studs should never be in a sheer situation if they are tightened to the correct torque. I can't think of the correct terminology but what
I'm getting at is that the wheel studs only hold the wheel against hub. They don't drive the wheel (think of knock on wheels) and they
don't support the weight of the car either. All these forces are transmitted by the friction between the wheel and the hub not by the bolts.
Has anybody experienced wheel bolts shearing when they have been tightened to the correct torque every time?
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Avoneer
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| posted on 4/9/07 at 09:12 PM |
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I wonder how common this is on live axle track days as I've never heard it mentioned and it could have saved me an A048!
Looks like my bushing wasn't to blame after all.
Gonna start a new thread and see how common it is and probably get a 5-10mm spacer.
Cheers,
Pat...
No trees were killed in the sending of this message.
However a large number of electrons were terribly inconvenienced.
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ChrisGamlin
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| posted on 4/9/07 at 09:20 PM |
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Ah that's a pain, yours was a bit worse than mine then, which only just brushed it and didnt damage the tyre other than a minor rub mark on the
edge of the sidewall akin to a minor curbing incident.
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Avoneer
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| posted on 4/9/07 at 09:41 PM |
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I can only imagine that the 48's didn't help either as they are so damn sticky, the chassis must have been moving on the corners and the
wheels not!
Pat...
No trees were killed in the sending of this message.
However a large number of electrons were terribly inconvenienced.
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RazMan
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| posted on 4/9/07 at 09:59 PM |
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quote:
Originally posted by daviep
Wheel studs should never be in a sheer situation if they are tightened to the correct torque.
You may be right and the shear issue is probably a secondary concern and would only happen with a wheel that has not been torqued up correctly.
Centralising the wheel on the hub is paramount so the hubcentric spacer is essential for this reason - even 1mm off centre (very likely with long
studs) will produce a hell of a wobble.
[Edited on 4-9-07 by RazMan]
Cheers,
Raz
When thinking outside the box doesn't work any more, it's time to build a new box
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ChrisGamlin
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| posted on 4/9/07 at 10:04 PM |
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Unless you've got slack in the panhard rod then it shouldnt move Pat, maybe a couple of mm with the flex in the bush I guess but not a lot. I
think its more tyre flex than anything else though.
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Avoneer
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| posted on 4/9/07 at 11:04 PM |
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Yeah - I was just over exagerating.
With my tyres down at 16psi, I can imagine how much they could flex on hard cornering.
Pat...
No trees were killed in the sending of this message.
However a large number of electrons were terribly inconvenienced.
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ChrisGamlin
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| posted on 5/9/07 at 08:06 AM |
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I guess in theory by the time the tyre is back round to that point it shouldnt be flexing that much (ie most flex will be at the 6-o-clock position
where it touches the road, probably no flex at 12-o-clock), but having seen photos of how much tyres flex its going to have an effect most of the way
around the tyre to some degree or other.
Chris
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RazMan
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| posted on 5/9/07 at 07:45 PM |
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Just a thought - you could maybe fit some of
these to steady your universal spacers. This would at least centralise them as long as the OD fits the spacer's bore size.
Cheers,
Raz
When thinking outside the box doesn't work any more, it's time to build a new box
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