Bolt torque

[Al Powell]

Bob asked:
From: "KUNZ,BOB (HP-Boise,ex1)" <bob.kunz at hp.com>

OK, guys. I've looked for the actual torque on this bolt and have found so
far...

330 ft-lbs at the bolt
450 ft-lbs at the bolt
400 ft-lbs at the bolt
258 ft-lbs at the end of the 2079 tool

So, anybody have the actual torque for this bolt?
--bob

Bob, I had the same question about the bolt torque when doing my timing belt
on my 1990 200.  As I recall, the torque figure I finally came up with after
some good samaritans shared it with me was about 340-360 lbs/ft or something
in that area.  This was a whole lot more than any conventional torque wrench
can measure, and I suspect that the only reason they use tool
whatchamacallit is to reduce the torque to a number that torque wrenches
available to most mechanics can actually deal with. So here's what I did:

1) I got a socket to match the bolt, and put a 1/2" breaker bar on it;
2) I bought four feet of 1/2" pipe, just the right diameter to slip over the
breaker bar;
3) Standing beside the car, I then used my finely calibrated forearms and
sublime physique to apply approximately 85 pounds of push on the bolt.
Remember, 10 pounds of force at 1 foot from the center of turn (10
foot-pounds) is 40 foot-pounds when applied four feet from the center of
turn.  4 x 85 = 340 lbs/foot, and who gives a rat's ass about the
difference??????

And my 200 is still running nicely some years after this kentucky-windage
technique was used.

Here's the deal: if you're tightening a bolt that takes 40 lbs/ft of force,
then 10 pounds either way is a 25% error and could be significant.  But
let's all get a life here - - - when you're dealing with 350 foot-pounds,
what difference does 20, 30 or even 50 foot-pounds either way matter?????
If the stinkin' bolt is tight at 350, it will still be tight at 320.  it
will still be tight at 380. It probably won't fall out if it's only
tightened to 300, and it probably won't twist off if it's tightened to 400.
So I figured that my procedure would yield results well within the range
that I fondly call "close enough"...and it did.

So my vote is to get out the four foot length of pipe, cinch the sucker down
till YOU think it's good, and go have a beer.

************************************
Al Powell
apowell at gocougs.wsu.edu
1958 Fiat 1200 Transformabile Spyder
1983 Datsun 280ZX Turbo
1993 Audi 90Q
1997 Chebby Blazer
1999 Chebby Blazer
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