You got it Bill.
----- Original Message -----
From: "Bill Babcock" <BillB@bnj.com>
To: "'Barr, Scott'" <sbarr@mccarty-law.com>
Cc: <fot@autox.team.net>
Sent: Thursday, March 28, 2002 12:14 PM
Subject: RE: flywheel bolts
> Hard versus strong is easy to explain, but I'm not sure what physical
> parameters denote it, certainly not grade 5, grade 8. A strong bolt can
> stretch but won't break, a hard bolt won't stretch but when it reaches
> yield it cracks rather than stretching. The ARP bolts seem to be both.
> From my limited metallurgy reading (mostly associated with knife making) I
> think the "psi" number is strength, that is, they stick a sample in a
> measuring tool that tries to pull it in two. Hardness is a different
> number, which as I recall is measured by pressing a graduated diamond
> point into the metal and seeing how deep it penetrates with a specific
> force applied. Sometimes you see knives with little dimples where they did
> that. There are a bunch of other tests, like Charpy V-notch that tests the
> resistance to shear forces. And Brinell that measures another aspect of
> hardness. But it all distills down to "buy some really good bolts", and
> that basically means "pay ARP what they ask".
>
> I probably should read a couple of the metals books in my library. It's
> interesting stuff.
>
> -----Original Message-----
> From: Barr, Scott [mailto:sbarr@mccarty-law.com]
> Sent: Thursday, March 28, 2002 11:17 AM
> To: Bill Babcock
> Subject: RE: flywheel bolts
>
>
> Yes, I thought I'd switch to ARP bolts, anyway. I still don't know how to
> evaluate whether a bolt is "hard" or "strong", but at least I'm more
> comfortable that my flywheel bolts won't break... :-)
>
> Thanks!
>
> -----Original Message-----
> From: Bill Babcock [mailto:BillB@bnj.com]
> Sent: Thursday, March 28, 2002 1:17 PM
> To: 'Barr, Scott'
> Subject: RE: flywheel bolts
>
>
> Once I switched to ARP bolts I haven't had any more bolt breaking or
> stretching problems. I'm considering adding two more bolts as KAS
> suggests, but one of my engines has a billet crank which is so hard it's
> almost impossible to drill.
>
> -----Original Message-----
> From: Barr, Scott [mailto:sbarr@mccarty-law.com]
> Sent: Thursday, March 28, 2002 5:00 AM
> To: Bill Babcock
> Subject: RE: flywheel bolts
>
>
> Hi Bill. Have you ever gotten a good answer on just what is meant by
> "hard"
> in this context? If I were shopping for "hard" bolts, what would I look
> for
> -- what sort of rating system are we talking about? For example, I don't
> think we're talking about the Grade 5, Grade 8 type system. And not the
> AN
> grades. Are we talking about the "PSI" grade that I've seen on ARP rod
> bolt
> packages? (e.i., 320,000 PSI)
>
> Scott
>
> -----Original Message-----
> From: Bill Babcock [mailto:BillB@bnj.com]
> Sent: Wednesday, March 20, 2002 1:07 PM
> To: 'Mike Munson'; fot@autox.team.net; gatriumph@gatriumph.com; 6pack
> list
> Subject: RE: flywheel bolts
>
>
> Yup. Breaking the bolts is a common topic. You need to get some good
> bolts, not just strong but hard so they won't flex. Kas has posted
> extensively on this issue. When the engine is running at any serious RPM
> the crank flexes enough to make the flywheel wobble like a cheap yo-yo.
> Lots of force is being applied to the bolts, and it's not all in shear.
> I've taken out crank bolts that were seriously stretched, and broken more
> than a few
>
> -----Original Message-----
> From: Mike Munson [mailto:fasttrs@mindspring.com]
> Sent: Wednesday, March 20, 2002 10:51 AM
> To: fot@autox.team.net; gatriumph@gatriumph.com; 6pack list
> Subject: flywheel
>
>
> Hi guys,
>
> I pulled the transmission on my TR6 IT racecar Tuesday. The flywheel was
> held
> on by two bolts(barely), and the other two bolts were broken. The
> crankshaft
> looks like there is metal from the flywheel molecularly bonded to it! Has
> anyone ever experienced this before or have an explanation for this
> phenomenon? The PO must have run it a while with the flywheel loose.
>
> Mike Munson
> Atlanta
> 73-6 AC,Hardtop,4Wheel disc brakes
> 70-6 IT Racecar
> 80-8 wanting affection
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