[DeTomaso] Bolts

Ross Harvey chaos at ross.aero
Thu Mar 8 15:58:34 EST 2012


Err, wait a minute, grade 8 is not "better" than grade 5 and cannot
necessarily be substituted.  It is a little bit stronger (150 kpsi vs
120 kpsi) but it is way more brittle.  Preload becomes vastly more
important and the usual rough approximation of preload, torque, is
often not accurate enough.

As a general rule, if you make steel twice as strong you also make it
ten times more brittle.

And for this reason, the aerospace equivalent of grade 8 is rarely
used in aircraft.  Yes, it saves a little weight and size. No, it's
not worth it.  A classic mistake involves bolting a propeller on with
hardware-store grade 8 bolts.

I'm sympathetic to people who want a higher class of hardware, I'm
like that, but if you are that guy the solution is usually to buy some
nice aircraft bolts. I wish there was a way to do that for metric
fasteners.

On Thu, Mar 8, 2012 at 8:57 AM, bill gaino <gaino at earthlink.net> wrote:
> Jeff, I would at least use a grade 5. If you gotta buy them ..you may as well get grade 8. The bell house will break before the bolts do. IMHO Bill 1362
>
> -----Original Message-----
>>From: Jeff Detrich <jjdetrich at gmail.com>
>>Sent: Mar 8, 2012 11:23 AM
>>To: 0 <detomaso at realbig.com>
>>Subject: [DeTomaso] Bolts
>>
>>Do the bolts that attach the trans and bellhousing to the engine need to be
>>grade 8?
>>
>>Thanks,
>>
>>Jeff
>>6559
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>
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