streeeeetchy bolts

Styve100

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Hi all, just thought I would share this one with you.
In the process of tarting up my 1150GS, started rebuilding today with putting left hand head on, with modified cam chain tensioner and refitting the cam sprocket.
This is tightened to 65Nm.
Anyhow, engine is still locked at TDC, started to tighten bolt, put torque wrench on set to 65. When approaching tighteness.... I was getting that sick feeling of, this is going to strip, its not tightening any more, just turning....
Backed off and tried tightening to different torques, 30, 40 50 all ok, until I went past 52, then, just slowly turning, took out again, checked bolt, ok, hole ok, threads ok?
On the phone to local dealer? no clues, is sprocket on right yes, etc etc.
Anyhow, tried again tonight with a different torque wrench still the same, took out bolt and lo and behold it had had a severe slimming near the head, stretched by quite a few millimetres, so will be in tomorrow for a new bolt. I have to say as an engineer myself, I have rarely had a bolt go like this on, I figure these bolts in such places on the engine are quite hard and not as soft as this appears to be....
Just a point to be aware of i spose. :thumb
 
Seems like you know what you're doing, but you were on the Nm scale and not the lbft scale were you? I've put some black tape over the Nm scale on my torque wrench after reading Nm from the book and dialling in that number of lbft.

Mark
 


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