Date: Wed, 22 Oct 2003 04:02:14 EDT
Reply-To: Oxroad@AOL.COM
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Jeff Oxroad <Oxroad@AOL.COM>
Subject: Re: sheer bolts/steering column
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I think I started this thread, and I have read the discussion and I've
reached my conclusion: They are called sheer bolts because they sheer in the
unlikely event of a collision.
I remember learning of the "sheer key" in lawn mower engines in shop class in
high school. The "sheer key" sheers off when the lawn mower blade hits a
hidden stump, let's say, to prevent irrepairable damage to the engine.
Now the heads sheer off on installation of these bolts, this we know. And
that might have to do with exacting the amount of torque when they are installed.
But that cannot be the end of the sheering. If only the heads sheered, they
would be called sheer head bolts. For my money the bolt is the part of the bolt
that does the work. And so "sheer bolt" is the name given to a bolt who's
working part is designed to sheer. And the reason the heads sheer off is to
prevent any--even slight-- over-torquing which would surely sheer the bolt--as it
is a bolt designed to sheer long before a sturdy normal bolt would fracture.
I base my conclusion on two things. Both amount to hunches. And therefore my
thinly veiled moment as an expert has been undone.
However, while they are aptly named sheer bolts, I would also agree they do
seem to work toward an anti theft device as well. It seems if these bolts were
removed the steering lock would be slightly compromised. Although I'd have to
think only slightly as with the bolts undone the ignition lock would have to
spin with the steering wheel. It seems the wires into the ignition lock would
prevent the steering wheel from being turned too far without obvious
consequences.
Perhaps those crafty germans have figured out a way to kill two birds with
one stone.
I also base this conclusion on the fact that my step dad worked for Volvo in
the middle 70s I remember seeing lots of literature about all kinds of things
designed to break away in the unlikely event of a collison to allow the engine
to drop under the vehicle instead of crashing through the vehicle into the
passenger compartment. Same with the steering column and the like in the Volvo.
Volvo and Volkswagen start with the letter "V". Need I say more? (FWIW I even
saw plans for a prototype for a hinged bar of sorts off the front of a Volvo
that would, if the vehicle hit a child or pedestrian, lift the child onto the
hood of the vehicle--this one never made it into production as you know. I
think again for obvious reasons.)
I've ordered my replacement sheer bolts from Rennie at Power VW in Torrance.
With the list discount he offers it's worth the chance I might be wrong about
needing them. My grandad, who was a german mechanic, taught me as a young boy
the engineers who designed the car knew a heck of a lot more about automobiles
than I ever would--and so he advised not to second guess them, but instead
learn what they had in mind. In the event that I couldn't figure it out, he
advised still put it back the way the book says. He was a bit of smart a**, but
often right.
And in closing I should add I really don't know the answer. So I am not
saying anyone is right or wrong. I'm just adding my 2 cents because I should be
sleeping, but instead I opted for a lot of coffee a little late the game.
Best
Jeff
83.5 Westy
LA,CA
In a message dated 10/22/2003 0:13:22 AM EST, doktortim@ROCKISLAND.COM writes:
<< No, I'm sorry, but they are called shear bolts because they are designed to
shear in a collision. Look over that design closely and you will see that
in a frontal impact when your chest hits the wheel and the bolts shear, the
steering column will just slip apart and you will break less ribs. >>
