[Tigers] Crossmember Installation Headache

[Jim]

I must be missing something...when I go to my local industrial  
supplier, they only have 2 kinds of 'inch' bolts... UNC and UNF ! All  
my taps and dies are the same. What's different about SAE?? Or is that  
a U.S. term for a world standard?
I bought new UNF grade 8's for the crossmember... Ran a long tap  
though... No problem at all...reused those nice thick stock washers  
though...
Also, I don't see a need for those 'long thread' 3/8" UNF bolts for  
the fulcrum pins... If you reach into the crossmemer, you can feel all  
that extra thread sticking through the threaded backing plate... Just  
use shorter bolts with the normal length thread and they will still  
stick out the back a little...

Jim
B382000446


Sent from my iPhone

On 2010-07-14, at 4:19 PM, "Would U. Believe"  
<mcdangerous at verizon.net> wrote:

> Here's a dumb question:  Since these bolts are such oddballs in the  
> US,
> what's to stop people from using a 1/2-20 SAE tap and just  
> installing new
> Grade 8 SAE 1/2-20 bolts?  Just curious.  If that's an insane idea,  
> is there
> a source for suitable and appropriate replacement crossmember bolts
> anywhere?  Thanks.  M
>
>
> On 7/14/10 10:57 AM, "Smit, Theo" <Theo.Smit at dynastream.com> wrote:
>
>> Good question! I re-read the various standards (at least as  
>> described by
>> Wikipedia) and combined with the Alpine parts reference cited  
>> earlier I don't
>> think that these are British thread after all.
>>
>> BSW (British Standard Whitworth) in 1/2" has a 12 thread pitch,  
>> while BSF has
>> 16 threads per inch. We know that the chassis bolts are 1/2-20. UNF  
>> is spec'ed
>> at 1/2-20 while UNC is 1/2-13.
>>
>> So the question that remains is, are these bolts made with a 60  
>> degree thread
>> profile or not? If they are, are they designed for an interference  
>> fit (which
>> might explain why a standard die will remove material from the bolt  
>> threads)?
>>
>> As already stated, these bolts have a longer threaded section and  
>> shorter grip
>> length (thanks Mayf!) than a standard SAE bolt, so you can't easily  
>> go to your
>> local ACE hardware store to buy replacements. Using a thread die to  
>> put extra
>> threads on a store bought bolt is dangerous because it causes  
>> stress risers at
>> the root of the threads - conventional bolts have the threads  
>> rolled into
>> them, which essentially forges the threads into the bolt and  
>> strengthens the
>> threaded area.
>>
>> Theo
>> ________________________________________
>> From: tigers-bounces at autox.team.net [tigers-bounces at autox.team.net]  
>> On Behalf
>> Of Carmods at aol.com [Carmods at aol.com]
>> Sent: Tuesday, July 13, 2010 3:07 PM
>> To: tigers at autox.team.net
>> Subject: [Tigers]  Crossmember Installation Headache
>>
>> Jul 13, 2010 09:52:38 AM, Theo.Smit at dynastream.com  wrote:
>>
>> they're British fine thread which is almost but not quite  the same  
>> as SAE:
>>
>>
>>
>> Theo,
>>
>> Are you sure those bolts are British Standard Fine Thread  (BSF)?
>>
>> What size are they?
>>
>> John Logan
>> _______________________________________________
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