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Correct caliper bolts

lmoengnr

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Why are they single use? Are they like the bolts used in the Cylinder heads and stretch once torqued?

They have a single use, thread locker applied to the bolt.
Not sure about TTY on the Brembo's fitted to Holden's, but the caliper bolts on HSV AP calipers just have a torque figure.
 

dgp

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The manual says to replace the bolts, but does not say that they are TTY, it does say to torque them then to 40Nm plus 90 degrees. I have cleaned old loctite off caliber bolts in the past and reused them after applying new loctite.
 

EYY

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Because of this maybe ?

A torque to yield fastener (TTY) or stretch bolt is a fastener which is torqued beyond the state of elasticity and therefore undergoes plastic deformation, causing it to become permanently elongated.
But is it a torque to yield or torque to angle fastener? It's important to know the difference. Torque to angle is also very common as it ensures more accurate torque application because friction plays a considerable role when tightening fasteners beyond a certain point. That's why most critical bolts are torque to angle - as it results in greater accuracy.

Most of the time tty bolts have a slightly reduced shank where the stretch occurs. Toyota even specify that you can reuse tty bolts providing you check the length of the old bolt with the length of a new bolt. If they haven't stretched then you're good to go. But it's cheap insurance to replace them wherever possible, especially with something critical or difficult to replace like head bolts, rod bolts etc.
 

BlackVXGTS

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Interestingly, the Holden Workshop manual says front caliper bolts on VFs are 40Nm + 90 degrees, except for HSVs which are 160Nm. All rear caliper bolts are 110Nm.
 

3rspecB

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Interestingly, the Holden Workshop manual says front caliper bolts on VFs are 40Nm + 90 degrees, except for HSVs which are 160Nm. All rear caliper bolts are 110Nm.

The Holden torque + angle spec delivers a higher final torque than 160nm ;)
 

Ron Burgundy

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The Holden torque + angle spec delivers a higher final torque than 160nm ;)
Sooo if the torque and angle is for instance equivalent to 180nm why would not they just say 180nm torque rather than x torque + x degrees...
I am sure there is a goid reason for this...i just don't know the answer :)

Edit.
This explains it. It is basically a lot more precise...

 
Last edited:

Mattricho

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I was under the impression that if you’re given a torque setting of x plus x degrees that it is for torque to yield bolts and that the x degrees is for the bolt to stretch. (Meaning single use)

Where as if your given a torque setting of x and that’s it then you can reuse the bolts
 
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