[s-cars] sheared crankshaft pulley

[Peter Schulz]

Mechanically speaking, the pulley key way prevents the gear from 
rotating out of position on the crank-
Yes, the bolt holds the gear onto the crankshaft, but it cannot 
prevent the gear from rotating out of position....
300lb fts of torque or not on that bolt - over time a gear with a 
trashed key way will move out of position.

Given the price of the gear relative to the cost of destroying the 
motor ( and the likelihood of this not happening in a good location) 
aren't we wasting alot of energy debating a <$100 part that may need 
replacing once every 60k miles?

Maybe I would hold off on replacing one on a car with less than 100k 
miles, but many of us have cars with over 200k miles on them now -
and we aren't the original owners, so we don't know whether past 
repair work was done properly.

I know with the next TB job on my green wagon ( 240k miles), it's 
going to get a new gear and a CPS as part of the job.


My two pfennigs ( replaced by the Euro cents)
-Peter


At 01:02 AM 1/22/2009 -0500, djdawson2 at aol.com wrote:

>Your statement that the bolt doesn't hold the gears in place... I 
>would argue vigourously.? The keyway is for positioning, the bolt 
>provides the clamping force.? What's the torque spec for a crank 
>bolt?? Think it's that high because the load is on the key?? I don't 
>think so.? Tell you what... why don't you try firing up a car with 
>either the cam or the crank bolt tightened to "snug" and see how 
>long the key survives?
>
>
>-----Original Message-----
>From: QSHIPQ at aol.com
>To: Djdawson2 at aol.com; cody at 5000tq.com; 
>david.giannandrea at sbcglobal.net; s-car-list at audifans.com
>Sent: Wed, 21 Jan 2009 9:27 pm
>Subject: Re: [s-cars] sheared crankshaft pulley
>
>
>You guys are kidding right?!
>
>
>Timing Belt with new gear and new bolt only, both are one time use
>IME/O.? The bolt doesn't hold that gear in place, the key does, BTST
>failure.? IME/O it has nothing to do with the install or the removal tools,
>it has to do with heat cycles, stress, and shear.? The bolt is 12bucks and
>is a 1 time stretch bolt, the gear is 40 bucks and it's key is 
>crappy pot steel
>that many times is hard to see the cracks.

-Peter Schulz
Chelmsford Ma, USA
http://www.naaclub.org/

1995.5 S6 Avant Emerald/Ecru
1995.5 S6 Avant Silver/Platinum
1991 90 20v Q Red
1991 CQ silver  (eS2 recipient)