Prop Nut & Bolt Torque Sequence

[chevelledude13]

I have a ZDZ80 which has 6 smaller bolts and a large nut on the main shaft for bolting on my prop. When I snug down the large nut, the 6 outer bolts get loose...so I tighten the 6 bolts, but then the big nut is loose again...so I tighten the 6 bolts. You get the picture...tightening one makes the other loose. What is the correct method for snugging down the nut and 6 bolts. When do I stop cranking on them?

[Altavillan]

You are doing it right. Just tighten them evanly till they are all tight. If you aren't sure how tight to get every thing, get an inch pound torque wrench and follow the torque specs given for each bolt.

[JEFFRO503]

I was using all 6 bolts on my props as well.....then decided using two was good enough. especially when your testing a bunch of props during the day....you spend more time unscrewing and putting them back in , then ya do flying hehe.

[rcign]

The six small bolts are just overkill...The center nut holds the prop on....Get it TIGHT, snug up the small ones...The prop will never come off if the center nut is tight...If the 6 bolts shear the prop will only get tighter....

[dick hanson]

I hate to be a spoil sport but on the ZDZsetup DO NOT rely only the centerbolt !!
It is a easily loosened and was never intended for providing the clamping pressures
I have seen this bolt -(which by the way comes as a loose piece with the new engines) loose on a number of setups
I love the ZDZ engines
It's the favorite pattern engine for me

But the factory recommended setup must be followed .
Further - at one point in time, ZDZ furnished a titanium center bolt which would n could n DID snap off.
The six prop bolts, if the prop is correctly drilled n fitted , will allow drop thru installation of all of em and a standard 3mm or 4mm T handle will supply more than the necessary torque -even for a "non athletically inclined" person.

[rcign]

Well said

[Captinjohn]

I guess I thought wrong...I aways thought the 6 bolts was helpfull in getting prop to track. Any input on that idea. Best Regards capt,n

[Captinjohn]

	Quote: Originally Posted by Captinjohn
	I guess I thought wrong...I aways thought the 6 bolts was helpfull in getting prop to track. Any input on that idea. Best Regards capt,n

FURTHER QUESTION I thought I read there was a way to tighten prop bolts to improve the tracking of a prop & still end up with all 6 bolts tight. Can anyone remember such a article like in a RC magizine about prop tracking? Sure do not think I dreamed it up!!!! Thanks Capt,n

[Tired Old Man]

There has been some discord on that subject.

Prop tracking is a function of the "squareness" of the prop hub against the engine hub. If either is not dead flat blade tracking will be off. The only way the prop bolts could change tracking is by unevenly crushing the prop hub. Not the smartest thing to do. Re-shaping the back of th hub or having the engine hub machined flat if it's the culprit are the only "correct" ways.

BTW, the center nut on a BME 116 is the primary fastener. The outer bolts are locators and are not to be used as primary for prop retention. Tightening down the other bolts will break the prop "washer". So know your engine and/or ask the manufacturer if there are any questions about which bolt does what.

[Captinjohn]

TOM...You mean kie this....

[Tired Old Man]