Wrong torque in cambelt guides

Can't quite believe this has never been noticed before but maybe this will save someone else the nightmare of stripping the thread on the adjustable tensioner nut as I did earlier.

In Skinflints PDF guide (version 2) and also in this generic Fiat 20v engine cambelt guide:

http://download.fiat-bg.org/Books/Coupe/Fiat%20Coupe%20cambelts%2020v%20all%20models.pdf

it specifies the torque for the nut securing the adjustable tensioner as 50NM. This is double the 25NM specified in the coupe engine manual and is way too high for an M-8 nut.

The fixed tensioner bolt is also specified in the engine manual as 25NM, but is listed as 50NM in the PDF guide.

Just hope I haven't damaged the stud and that the nut is still available from Fiat!

Does seem like an error, however it's worth noting that the bolt size does not by itself dictate the torque setting. Material/class also requires to be taken into consideration.

True, but there are still max. torque settings due to the physical size of the fastener.

eg. from the "Standard Torque Values table" at :

http://electronicfilters.tpub.com/TM-10-4330-237-13P/css/TM-10-4330-237-13P_105.htm

even a 12.9 strength M-8 is only rated to 45NM, a 10.9 strength to 35NM, an 8.8 or 9.8 strength to 25NM and 4.8 strength to 13NM.

I just had another look at the nut and it appears to be marked 9.8 on the lower side so that ties up perfectly with the 25NM torque specified in the coupe engine manual.

So the 50NM from the guides is definitely wrong. I guess most people have just been tightening the nut by hand and not reaching much above 20-25NM , but I used a torque wrench and could feel the thread stretching before it hit the 50NM setting.

Hopefully they've made the stud a 10.9 and the nut has deformed first!

The lock nut was still available from Fiat and it torqued down to 25nm no problem, so all is well with that.

Engine sounds fine and idles well but not taken it out on the road yet and now I've spotted gearbox oil leaking from both drive shaft seals after doing the clutch... seems there's always something else to go wrong! So it'll need stripped down again, happy days.