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Crank Bolt Torque?
I just need a little clarification on the torque specs in the Parks repair manual. In the torque specifications for Shimano crank bolts they give a broad range of torque values(305 inch pds - 390 inch pds).
-How do you know what to tighten the bolt to??
-Should you go to the lowest, middle or the highest torque value??
-If the cranks don't get tight enough, you can end up with a wallered out crank that will never stay tight, right??
-If you go too tight you might split the crank, right??

Sorry for all the ??'s
Thanks painkiller.
The reason I ask is I torqued a new crankset to the middle value and the cranks kept loosening up after every ride. After the first ride and discovering the loosening, I cleaned up the bolt and threads and then applied blue locktite, then torqued to middle value again. I let the locktite cure for the recommended time and then went for an average ride(15-25 miles). They loosened again. I then repeated the same procedure, but with a little tighter torque and a 2x recommended threadlock cure time(2 days). They loosened again after an average ride again !!
After this, I tried again with the max torque and let the locktite dry for 4 days. I did another average ride and they loosened again !!!
What is the deal ???
This was a brand new crankset on a roadbike with low to medium crank power being used. I have'nt even stood up on the pedals to really crank down on them yet !!
Not sure if it matters, but this set uses a 8mm hex head bolt instead of the normal 14mm bolt. Does this matter??
If you replaced the cranks but not the spindle you may have mixed two incompatible tapers - JIS and ISO. the BB. If that is the case and you are lucky you may be able to keep them tight once you have replaced. If not you unfortunately are possibly out of luck.

Otherwise I would have no easy explanation, as the middle range of torque should be sufficient - we went decades wrenching on square taper BB's and no torque wrenches without a problem.
The crank bolt type does not matter.

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