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expensive bolts

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Mail From: (email redacted) (DUHART JOHN)

Hey All,



Here is part of a previous message.



> Question 2:

> I am preparing to order some parts for a motor bottom end re-build.

> I thought I would follow the manual recommendation to replace the

> con-rod big end bolts rather than re-use the old ones.

> Well, TRF wants $5.25 ea. for these bolts. Are they gold plated? ;-)



What bolts are we talking about here? The bolts that hold the oil-pan
to the block? "Con-rod big end bolts", what are these? Why would you
replace bolts rather that reuse? I never knew bolts wore.



Thanks,

JHD IV





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Mail From: "Michael Bayrock" <(email redacted)>


I remember following a thread about a year ago that suggested
many high grade nuts, bolts, and other assorted hardware could be
found at your local Caterpillar parts department.

I haven't had an opportunity (or a need) to see what is indeed
possible, but they are on my 'if all else fails' list.

As always, ymmv, I own no part of the company, etc...

----------------------------------------------------------------
Michael Bayrock
1971 GT6+ KC80064L
(email redacted)



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Mail From: dan parslow <(email redacted)>

From: ALPHA::DJP "dan parslow" 19-JAN-1996 10:19:20.42
To: SMTP%"triumphs.autox.team.net"
CC: DJP
Subj: re: expensive bolts

Pegasus Auto Racing supply offers aircraft grade bolts in
standard sizes, grip lengths in 1/8" increments. Shouldn't
be hard to find what you want.

If you don't want to go mail order or want to see before you
buy, try the shops at your local airfield. (Check the Yellow
Pages.)

I'm no expert, but such secondhand wisdom as I've heard rates
aircraft grade well above SAE grade 8, and apparently there's
a great deal of bad pacific-rim hardware out there masquerading
as SAE graded when it isn't. Caveat emptor when comes to your
local hardware store.

- DJP


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Mail From: (email redacted) (Milo V. Kral)

>
> I remember following a thread about a year ago that suggested
> many high grade nuts, bolts, and other assorted hardware could be
> found at your local Caterpillar parts department.
>
> I haven't had an opportunity (or a need) to see what is indeed
> possible, but they are on my 'if all else fails' list.
>


I coming in on the middle of this discussion, so I don't really know the direction(s) that have been pursued. However:

The best way to get grade 5 bolts, which should be more than adequate for attaching connecting rod and main bearing caps, is to go to your local bolt and screw store. This may sound obscene, but every medium size city probably has one or more of these establishments. For example, in Nashville it is "Capitol City Bolt and Screw".

The most convenient way is to buy from V.B., Moss or TRF. I would probably trust their quality control not to be duped by counterfeiters.

Now, regarding the re-use of bolts: if properly torqued, these bolts should be re-useable IF they were initially designed to be loaded below their endurance limit. In other words, if they were designed for infinite life with an appropriate safety factor.

Here's my disclaimer:
I haven't had a mech. eng. class or used this training for about 12 years. There's a lot more to this than the simple approach that I have used. Sending this kind of note out to the internet audience is flame-risky because it is well-educated (I'm not being sarcastic). On the positive side, if I'm wrong, then I'll hear about it (for sure) and I'll learn something.
Milo Kral
Applied and Engineering Sciences
Vanderbilt University
(615) 322-2756


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Mail From: John Wroclawski <(email redacted)>


From: dan parslow <(email redacted)>

But such secondhand wisdom as I've heard rates
aircraft grade well above SAE grade 8

There are many strength grades of AN / MIL-spec hardware, just as
there are many grades of SAE hardware.. The specs define a number of
properties of the bolt, of which strength and hardness are just
two. If I recall correctly yer basic common AN bolts are somewhere
closer to SAE5 than SAE8 in strength, but would need to look it up to
be sure. And remember that there is such a thing as using too high
grade a bolt - with hardness comes brittleness, which is a problem in
bolts which are shock-loaded.

and apparently there's a great deal of bad pacific-rim hardware out
there masquerading as SAE graded when it isn't. Caveat emptor when
comes to your local hardware store.

Indeed, although the AN bolt market isn't entirely immune from this
problem either. One good source of reasonably priced, reasonably
reliable graded hardware is your local (?) agricultural machine dealer
(Cat, Deere, etc). They usually have bolts obtained directly in the
original packaging from US manufacturers, which about the best you can
do short of ordering 10,000 direct from the manufacturer yourself.

-john


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Mail From: (email redacted) (Bruce T. Clough)


Okay folks, I really tried to stay out of this conversation, but since it has
wandered so far I thought I'd bring some reality to it.

The original question (paraphrased as I remember it) was:

"New big end bolts cost $42. Can't I get cheaper bolts at a hardware store
which will work just as well?"

Besides all the arguements about fatigue life, grades, torquing procedures,
et al, look at it this way:

You spent $300 on new pistons
$200 boring the block
$100 grinding and balancing crankshaft
$250 for new camshaft
$400 for rebuilt head
$100 balancing pistons and rods
and hundreds of $ on other stuff you need to do for a rebuild. This doesn't
count the manhours you've put into the effort!

What's $42 for the bolts, especially if failure of even one bolt will trash
your engine?

If your going to do it, do it right, and do it right the first time.

If you don't want to spend the money to fix it right, do you have the money
to fix it again?

Have a great weekend all!

Bruce Clough



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Mail From: (email redacted) (DUHART JOHN)

Hey All,



Thanks to everyone who explained what the "Con-Rod Bolts" are. Sometime
my lack of knowledge really shows. I hope I didn't cause anyone's eyes
to roll completely into the back of their head. ;-)



JHD IV







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