James
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| posted on 11/4/03 at 11:38 PM |
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Wishbone brackets bolts
For ease I've purchased the wishbone bolts from MK along with their crush tubes and washers.
What I'm concerned about is that the shaft of the bolt (the non-threaded part) is 36mm in length with the I.D. of the bracket being 47mm. This
means that the bolt it 'sitting' on the thread at one end of the bracket. This makes me wonder if there will be an issue of either the
thread collapsing/being damaged under the weight of the car or the bracket wearing heavily caused by 'cutting' from the thread.
I realise that the pressure of the nut face on the bracket should mean that most of the weight is supported away from the bolt hole so am I worrying
unduly?
Thanks,
James
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Rorty
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| posted on 12/4/03 at 02:33 AM |
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I've been wondering when someone would bring this one up!
In theory, you're right in thinking the threaded portion of the fastener should be outside the bracket.
In high tech situations, you should actually use AN/MS etc shear bolts(US military/aerospace etc), which have grip lengths in multiples of
1/16", which will allow you to choose one of the correct length. The shank should just protrude through the bracket, and the area of transition
between shank and thread lies under the washer. All AN/MS type fasteners have the same length of thread per fastener diameter.
In reality, as you're using a crush tube, and the size of the fastener is most likely overkill, I wouldn't worry. As long as the crush
tube is done up tightly, then the crushtube (asuming its ends are square to its axis) takes the radial load off the thread, and virtually makes the
whole crushtube/bolt/bracket one solid pivot.
Cheers, Rorty.
"Faster than a speeding Pullet".
PLEASE DON'T U2U ME IF YOU WANT A QUICK RESPONSE. TRY EMAILING ME INSTEAD!
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Rorty
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| posted on 12/4/03 at 02:40 AM |
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The top fastener in the pic below is a "standard" bolt, the rest are AN fasteners.
 
Rescued attachment AN_bolts.jpg
Cheers, Rorty.
"Faster than a speeding Pullet".
PLEASE DON'T U2U ME IF YOU WANT A QUICK RESPONSE. TRY EMAILING ME INSTEAD!
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James
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| posted on 13/4/03 at 10:07 AM |
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So I was worrying unduly then. 
Thanks mate- thought it was worth checking just in case.
Cheers,
James
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Alan B
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| posted on 13/4/03 at 12:24 PM |
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Rorty wrote (?)......
"the area of transition between shank and thread lies under the washer"
and
"As long as the crush tube is done up tightly, then the crushtube (asuming its ends are square to its axis) takes the radial load off the
thread, and virtually makes the whole crushtube/bolt/bracket one solid pivot"
Very key points IMO, and very well put.
At lot of basic bolted joint theory is widely misunderstood...(most people wouln't be aware that there was any more to it that just bolt - nut
- tighten....)
In other words, great question - great answer......
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