tighting a prop nut?
 

I was wondering how tight is to tight when tighting a prop nut....if I tighten it to much could it damage the engines bearings?....thanks....

RE: tighting a prop nut?
 

No, but if you mean "tightening" a prop nut, it could damage the prop, especially if it's wooden. After the nut is snug, tighten it about 3/4-1 turn more, depending on the material the prop is made from. Composite props will not let you tighten a nut as tight as wooden props will. It's wise to check the tightness of the nut on wooden props occasionally.

Dr.1

RE: tighting a prop nut?
 

cool...thanks for the advise..

RE: tighting a prop nut?
 

After all the years of wrenching I have done I have learned that if you want it tight then tighten it, but if you want it to never come apart lock tight it. So my method is simply to put a drop of blue locktight on it (not red, it's too strong for this) then snug it.

RE: tighting a prop nut?
 

I've gotten some decent size wrenches on the nut before, and you can REALLY crank down most composite props without a problem. I don't know how you are tightening it, but there shouldn't be any effect on the bearings. the only thing to worry about is the nut, engine crankshafts are hardened steel, so the nut should strip first.

RE: tighting a prop nut?
 

I have an 8 inch long adjustable that I use. I crank it down till I can't anymore. Your are not putting any preload on the bearings so dont worry about that. Most engines will have a slight back forth movement of the crank if you push and pull the spinner.

RE: tighting a prop nut?
 

when you tighten a prop nut you aren't tightening against the bearing just a shoulder,every thread size has a torque and there is two common standards NC and sae,or coarse thread and fine thread,and come in sizes like 1/4 20threads per inch.the threads we are tightening against are hardened steel i think maybe #8grade or better.general size is about 1/4 inch some are metric also, on 40 to mid size engine.the 1/4 inch prop nuts i put around 20 to25 pounds on them and the 5/16 maybe 30 to 35.and that is dependent on the type prop also,to me wood would crush more than plastic,going by the impressions left on the props.when you torque a fastener you are prestressing the threads,a lot of the new metric head bolts on automobile engines come in the engine overhaul kits because once you stretch them they cant be re stretched and have to be replaced.i looked under torque values and found this sight.
http://www.sizes.com/tools/bolts_SAEtork.htm
here is another sight for hardened fasteners.
http://www.armstrongtools.com/reference/storque.jsp
i like the double nut system some of the engine makers use wish they would put them on all of the engines.
metric threads have their own torque values,when i work on my automobiles or equipment that have metric values i convert them to standard values,i don't own any metric torque wrenches.i was a mechanic for 30 years and mostly on diesel and marine power plants so i tend to be heavy handed when i tighten my prop nuts,i have never had a propnut come loose yet,least not on the 2 cycle engines i have ran,have had one come loose on a 4 cycle saito because i didn't have room for the double nut.i looked at a few of the engine manufacture manuals and couldn't find any torque values for prop nuts,I'm sure there is a chart somewhere id be curious to see one if anyone has found any please post it.