RE: [Peugeot-L] TTY bolts, was: 505 Diesel radiators & heater core by-pass

Brian,

Thanks for your interesting comments.
If Peugeot's tightening toques do not force the bolts into the "plastic" region (that is, they remain elastic and return to their original length) then any bolts, cheaper ones than TTY can be used. Which begs the question why spend the exorbitant money on TTY ones?

Peugeot's reuse recommendation is also interesting: I guess the question is "how do you know if the bolts have been re-used once or five times". At the end of the day, as you say, they should be measured before reuse: Obviously, the undeformed (original) length would need to be known.

Con....

1979 504 GL
1984 505 STi
1998 406 SV

-----Original Message-----
From: Brian Holm [mailto:peugeots@vtlink.net] Sent: Tuesday, April 18, 2006 2:24 AM
To: con; peugeot-L@yahoogroups.com
Subject: RE: [Peugeot-L] TTY bolts, was: 505 Diesel radiators & heater core by-pass

Con

Peugeot says you can reuse the TTY bolts up to five times. The recommended tightening procedure should not deform the bolts plastically. They should return to their normal length upon removal. Of course they should be checked to be sure, and any that are too long discarded. They are now obscenely expensive if bought separately from Peugeot, not so bad if bought as a set with the head gasket.

Brian Holm

At 07:43 AM 4/17/2006, con wrote:

>I'll try to remember basic metallurgy.
>
>"Torque to yield" bolts (if torqued to specification) cannot be reused
>because they have been stretched beyond their "elastic" region, into what's
>called "plastic" region: Elastic means that they return to their original
>length. Once stretched into the "plastic" region they stay elongated and
>hence new bolts are required.
>
>Con,,,,
>
>

Brian Holm, Parts for Peugeots
at Peugeot Holm, since 1969
2120 Maple Hill
Plainfield, VT, 05667
802-454-7132, fax -1310

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