• If You Are Having Trouble Logging In with Your Old Username and Password, Please use this Forgot Your Password link to get re-established.
  • Hey! Be sure to login or register!

Torquing prop bolts

O

Oliver

Registered User
What’s the consensus on getting accurate torque reading on prop bolts?
I've been told that lube will give a false (over torque) reading.
My experience with dry (no lube), the bolts start “creaking” when getting tight making it difficult to get an accurate reading.
Some recommend parafin wax (?)
whats the correct procedure?
Thanks for your input,
Doug.
 
What Mike said. Standard hardware torques are usually dry. If lube is required, installation instructions will say so and indicate the correct lube to use.

Web
 
I like to clean the lugs with a brass rifle bore brush using a low speed drill, and a brass toothbrush on the bolt threads. This gets them shiny clean without any thread wear, and I've never had any creaking or sticking. They draw down quite smooth when dry this way.
 
Catto mentions parafin wax, but also uses Belleville washers for install.
McCauley, to my knowledge, makes no mention of thread treatment prior to prop install.
My small block Chevy build manual suggests lube with “light oil” on torqued bolts.
Is there no standard recommendation that would allow us all to arrive at a common value when torquing a bolt? Especially a prop bolt?
 
Last edited:
Oliver said:
Catto mentions parafin wax, but also uses Belleville washers for install.
McCauley, to my knowledge, makes no mention of thread treatment prior to prop install.
My small block Chevy build manual suggests lube with “light oil” on torqued bolts.
Is there no standard recommendation that would allow us all to arrive at a common value when torquing a bolt? Especially a prop bolt?
Click to expand...
I think the parafin wax is for the lugs so they slip into the the counter-bores easier, and if they're using Belleville's that's something new since I got mine. When I bought my Catto they didn't even provide bolts or a crush plate. Those had to be sourced from Saber mfg. Of course none of this was disclosed until AFTER I had my prop. They build a wonderful prop, but I've never been impressed with how the front end of that place is run. -- Sorry, venting....
 
Or . . . you could read the instructions from the manufacturer.

McCauley for instance, has different requirements for different installations. Some installations use dry torque, some use oil on the threads, and some require grease. Just do a search for service bulletin SB227B. It calls for 'light oil' for some and Mil-T-83483 grease for others. Also a big warning to never use dry torques when a lube is called out OR lubed torques when dry is called out.

There is no one way to torque all prop bolts.

Web
 
Never see the belville washers on the Catto. I always start the prop bolts by hand, snug with a speed handle and then torque and had no issues.
 
Spent a little time in the hangar today fooling around with a torque wrench and prop bolts.
As per sb227b (thanks Web) clean and dry threads on Lycoming.
With a very accurate and calibrated (Snap On) digital torque wrench, discovered that friction between dry washers, bolt head and spinner mounting plate can produce significant friction and false readings
lubticating washer surfaces eliminates bolt “creaking” also minimizes galling and crushing alum spinner mount.

That is my consensus on getting accurate prop bolt torque and my 2c for what it’s worth.
 
wireweinie said:
…..McCauley for instance, has different requirements for different installations. Some installations use dry torque, some use oil on the threads, and some require grease. Just do a search for service bulletin SB227B. It calls for 'light oil' for some and Mil-T-83483 grease for others.....
Click to expand...

Both my Cessna 100 series service manual and my McCauley C200/400 series operators manual call out for "clean and dry threads",
as does the paperwork that came along with the STC to install this prop.
But when I got my C201 back from overhaul, the prop shop supplied me a little tube of milspec grease and explicit instruction for lubing the nuts & studs before torquing.
I still have some of the grease left, but unfortunately now I can't find those darn instructions.

EDIT: Thanks for posting the link to that SB , Web.
Think I'll print it out and put it with my prop STC info.
It indicates that torque instructions are on a sticker on the prop itself, which I kinda recall now.
 
Last edited:
Steve Pierce said:
Were you using the Piper washers or AN washers? Interesting to know that the noise is from the washers.
Click to expand...

Using hardware provided from Dominion with Borer prop.
bolts, AN970 and AN960 washers with bolts.

Catto provides 24 belville washers and 6 AN960’s with their crush plate hardware kit.
maybe a recent thing,
torquing with belville washers (4 per bolt) is where I had the biggest issue with erratic readings from creaking bolts, assumed it was threads in the bolts/prop hub but not the case.
 
You must log in or register to reply here.

Similar threads

P
Torque for prop bolts?
Replies
10
Views
7K
cruiser
cruiser
vanair
Torque setting for Prop bolts
Replies
13
Views
5K
moneyburner
moneyburner
Ruidoso Ron
Proper prop bolt torque
Replies
12
Views
5K
Cajun Joe
Cajun Joe
B
Prop bolt torque, jury strut bolts + jury strut spacer tube
Replies
5
Views
5K
BritishCubBloke
B
gdafoe
Which wood prop to order?
Replies
6
Views
3K
Cubus Maximus
Cubus Maximus
Back
Top