But you can screw up the cranks if you overtighten them. If you get them too tight, the nuts/bolts will bottom out and you will forever have crank wiggle. Just use blue loctite or grease ( i prefer loctite here because once the bolt starts to loosen, it gets worse very quickly and most of us don't carry a wrench big enough to fix it) and torque it to 35lb*ft. Borrow a torque wrench from someone to get the feel for the right amount of pressure. Tightening a fastener until its about to strip is a bad idea.