[TowerTalk] Loose rotor bolts

[Jim Lux]

Michael Ryan wrote:
> Barry, There is an old saying that dates back before the turn of the
> century:  "If you want something done right you have to do it yourself."
>        For whatever reason your install in question did not last, perhaps
> the bolts were only installed hand tight while being lined up through the
> rotor plate and then were not tightened down appropriately ( just plain
> forgotten). Or those clever little devices, invented by that famous Italian
> metallurgist, Leroy Lock ( inventor of the LOCK WASHER ) were not used and
> the rest is history. In the past I have been up and down numerous towers
> like many on here have and done any number of chores but never had to fix a
> rotor because someone had not finished the job the first time which is what
> it sounds like happened in your case. Perhaps you'll have better luck this
> time around though. ( refer to my opening paragraph..) - Mike



also.. if you have a bolt that's being temperature cycled, lockwashers 
may not do much good, unless they're under a lot of tension (and 
depending on the kind of lockwasher).  If the bolt ever goes "slack" 
(due to changes in length with temperature, or loading) then the 
lockwasher won't do much to hold it, and vibration or further 
temperature changes will back it right off.

the high friction "nylock" type is a bit better.

An adhesive threadlocker (e.g. Loctite(tm)) is even better.

Or, wiring the nuts/cotter keys.

If you have a bolt under tension, and the tension is high enough that it 
never isn't under tension and the thread pitch is fine, then you don't 
worry about this (bearing cap and engine head bolts are good examples).
The fine thread is because a thread is basically an inclined plane, so 
fine threads is low plane angle, so the "turning force" vs "tension" is 
small, so turning force is very much less than frictional forces.

Here's an interesting observation.. I'll bet there aren't many 
lockwashers in your car(if it was built in the last 10-15 years), but 
there are either fine threads or adhesives or both. Automotive 
applications are a good example of an environment with both thermal 
cycling and vibration.

Jim, W6RMK