Thanks for that info. Yes. Basically, that was my understanding of the
TTY bolt. I'm ashamed to admit this, but I "reefed" really hard on
that crank bolt at least several times. Initially, my new torque
wrench refused to "click". (set to 66 ft lb) Comparing the damaged
bolt to 2 used bolts I have on hand, it's obvious where the damaged
bolt narrows near mid point. I'll post a picture.

Since damage to the bolt in question is obvious, my guess is that it
likely took the "hit"; it was the sacrificial item, not the crank
threads. I didn't see any damage at the sprocket.

Reading further, TTY (aka tension to yield) and stretch bolt may refer
to the same type of bolt. My Jetta Bentley manual refers to head
bolts, crank pulley bolt as "stretch bolts". It's interesting that it
specifies 'lightly oiling' threads/shoulder of crank bolt but not the
head bolts. (the head bolt has a thick washer, crank bolt no washer)

Neil.

On 12/1/16, David Bohannan <fjazzbass@gmail.com> wrote:

> Isn't that the purpose of a TTY bolt? Go in once and lock in place by its
> own actual deformation- from Wikipedia:
>
 ........
>
> My son used TTY on his cyl heads after someone reused old TTY bolts and
> ended up with a head gasket leak- one time use means they warp on the way
> in- right??? Is it possible that the torque you applied was just doing the
> work of locking it in place?

>> On Dec 1, 2016, at 1:41 AM, Neil N <musomuso@GMAIL.COM> wrote:

>> The crank threads looked ok, I installed a new bolt. Since the over
>> torqued bolt actually narrowed a bit about 1/2 way down the threads,
>> it's likely the only thing that got damaged.

--
Neil n

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