Wrong bolt/nut torque values in manuals

[northern]

Hi to all you!

Want to share a obvious mistake (at least fro me) I find in Haynes and service manual regarding bolt torque values.
it's front left engine bracket to frame mounting bolts - number 3 on attached screenshot. It's M8 and it's tighten torque value is 50Nm! I point my attention to this only yesterday, when I snap the very same bolt  . But if I would think a little, the same M8 lover bracket bolt have to be tighten only 23Nm. Also, I search internet - max torque for the extra strong 12.9 M8 bolt is 41Hm (seems like OEM engine mounting bolts are 10.9).

Other words - Suzuki service manual had COPY-PASTE typo, and Haynes just use the same value without thinking how logical it is.

Also, will remind (or inform) you what Haynes and Service manual have different torque value for rear sprocket nut - Haynes have 100Nm and service have 60Nm. 60 seems correct, cause Haybusa manual also have ~60, and it looks total overkill to have 5x100Nm nuts.

Hope, it will be useful information for at least some of you

[Speedy1959]

I found out the hard way on a previous Yamaha that the torque figures given for the rear sprocket nuts were miles to high!!
Same as with the GSX they were printed as 100nm !!!

[Red Biker]

uh oh, you do realise the sleepless nights this is going to cause what with my ocd!!! 

but thanks Northern great spot 

[Notty]

Thanks for that Northern - may go back to my old method before I bought 2 torque wrenches - tight then half a turn ! 

[T 24]

I have this kind of chart on the wall of my garage..

[northern]

This is good chart, Jussi, but in case of female thread in aluminium, those values could be to high.

[northern]

I found out the hard way on a previous Yamaha that the torque figures given for the rear sprocket nuts were miles to high!!
Same as with the GSX they were printed as 100nm !!!

I check today - Haynes manual for our 14, claims sprockets nuts torque value even 102Nm.
BTW - did you see eBay and Pro-Bolt aluminium sprocket nuts? will be interesting to test, how much torque will they handle? 60? 102? 

[T 24]

This is good chart, Jussi, but in case of female thread in aluminium, those values could be to high.

Yes, they can be too high, but the old rule from technical school works: The minimum lenght of female thread in mild steel should be 1.5 x D and in aluminiun 2.5 x D.