crank bolt torque (2021)

fiatfan · Jan 25, 2021

On the subject, do you punch the threads on the bolts, or use Loctite or similar?

SteveA · Jan 25, 2021

fiatfan said:
On the subject, do you punch the threads on the bolts, or use Loctite or similar?

Loctite.

champ7fc · Jan 25, 2021

Perhaps I am uninformed or misinformed but it is my understanding that reuse of crankshaft bolts and or nuts is not recommended due to the stretching of the bolts when installed, much akin to pulling the pin on a grenade. I could be wrong but it is something I did not do when I overhauled my 750, new parts all around.

baz · Jan 25, 2021

champ7fc said:
Perhaps I am uninformed or misinformed but it is my understanding that reuse of crankshaft bolts and or nuts is not recommended due to the stretching of the bolts when installed, much akin to pulling the pin on a grenade. I could be wrong but it is something I did not do when I overhauled my 750, new parts all around.

I too always replace them but I have heard some engine tuners say don't replace them because they have been tested and you know they work!!

Onder · Jan 26, 2021

Well then, er, how many of us have had an issue with the bolts failing?
I am just wondering...

dynodave · Jan 26, 2021

I have never replaced them. I always run a CEI tap and die over them (early engines) and use red 270? loctite on them. I also red loctite the rod nuts. Only place on commando for red! All else blue 242( or low strength wicking) ? only if needed...

filthyphil · May 30, 2022

Time Warp said:
Maybe they are the same as the Norvil studs. (I thought the bolts/nuts on the 750 went higher than 25 ft/lbs.

Here is one of my favourite quotes from another thread, this one from Mr Hemmings.

".....I never bother with a torque wrench on these, because unless you've got proper adaptors and things to get at the bottom ones I can't see the point of it. So the trick is just to use two good spanners,-and tighten them up."

I could have lent this to 'Mick.

View attachment 21241

Wouldnt you need to apply some factor to the torque reading due to the leverage of the attachment?

gortnipper · May 30, 2022

filthyphil said:
Wouldnt you need to apply some factor to the torque reading due to the leverage of the attachment?

No, not at a right angle.to the wrench. You do have to apply a conversion factor at other angles. This is because the center of the fastener remains on the same plane as it was before you added the extension, meaning that the overall effective length of the torque wrench stays the same.

Formula for Adding an Adapter to a Torque Wrench

Learn the formula for adding an adapter to a torque wrench today. We review what each value represents so you can ensure you have accurate measurements.

www.protorquetools.com

kommando · May 31, 2022

Onder said:
Well then, er, how many of us have had an issue with the bolts failing?

I replaced 2 studs on the last rebuild from a basket case job, they had been over torqued so much the TPI was less than 26 TPI. But they had not failed even though torqued past the plastic yield point so they were permanently stretched.

crank bolt torque (2021)

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