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Catto 2-blade prop torque
- Thread starter LarryT
- Start date
LifeofReiley
Well Known Member
My Catto two blade is 40 ft lbs, 7/16" Bolts. My three blade is the same.
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Not that familiar with the 2-blade, but my 3-blade has the torque information on the side of the hub between blades.
Bolt size is 7/16
..and yes, Mel, I am perfectly aware that the info is on the hub where I can't read it without taking the prop completely off (see post #1). Call me lazy if you wish, but I am really anxious to get this plane back in the air. I am going to write it on the spinner bulkhead. In the future I will just be able to back off the bolts, then re-torque the next day.
LarryT
..and yes, Mel, I am perfectly aware that the info is on the hub where I can't read it without taking the prop completely off (see post #1). Call me lazy if you wish, but I am really anxious to get this plane back in the air. I am going to write it on the spinner bulkhead. In the future I will just be able to back off the bolts, then re-torque the next day.
LarryT
LifeofReiley
Well Known Member
I'm confused!
I can read mine with the prop on the engine and torqued. It's on the SIDE of the hub.
Is yours different?
I don't understand why it can't be read without removing the prop.
What am I misunderstanding?
I can read mine with the prop on the engine and torqued. It's on the SIDE of the hub.
Is yours different?
I don't understand why it can't be read without removing the prop.
What am I misunderstanding?
LifeofReiley
Well Known Member
38 FT LBs was the old torque... 40 has been standard for the last 7 years for 7/16" Bolts. 
No sir, it doesn't. But I'm glad to see you (or a mod) deleted your subsequent rude, pointless, and snarky post. For a specific hub thickness, Craig uses the same torque for both 7/16" and 1/2" bolts. With a 3 1/2" thick prop hub, he ups it from 40 to 45 lbs. Standard torque value charts per bolt size do not apply to Catto props.
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LifeofReiley
Well Known Member
Nada... and you must be one that over torques every bolt. As I recall 3/8" is less torque on the 320 per bolt spec per Catto.
and I've talked to Craig about 45 ft lbs, you can go there but it is NOT required on the 7/16", 40 ft lbs is printed on my prop. I would do 45 ft lbs the 1/2" if as labeled. Have a beer.
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Nada... and you must be one that over torques every bolt. As I recall 3/8" is less torque on the 320 per bolt spec per Catto.
Done did.
But I've seen two different Cattos w/ 1/2" bolts with two different torque specs stickered on the side. Only difference was the hub thickness.
LifeofReiley
Well Known Member
YES
On the 1/2" it took the torque out to the limits... was 40 ft lbs then max at 45 ft lbs... you will not want to put 45 ft lbs on a 3/8 " prop bolt on a Catto prop period! RVadmirer... you are correct. Have another beer!
On the 1/2" it took the torque out to the limits... was 40 ft lbs then max at 45 ft lbs... you will not want to put 45 ft lbs on a 3/8 " prop bolt on a Catto prop period!
RVadmirer... you are correct. Have another beer!
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Interesting.....
as I just received a new prop from Craig for testing. Label shows 38 lb/ft for 7/16" bolts.
38 FT LBs was the old torque... 40 has been standard for the last 7 years for 7/16" Bolts.
as I just received a new prop from Craig for testing. Label shows 38 lb/ft for 7/16" bolts.
Rhino889
Well Known Member
Exactly why I take pictures and just loud them on photobucket.
Every time I told myself to remember "this"... I forgot
IO-360:
LifeofReiley
Well Known Member
I did when it occurred to me it might ruffle feathers. When it comes to safety I'd prefer to be accurate than PC. I think it's more important....
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humptybump
Well Known Member
AS noted above, not all of the Catto props use the same values. It is not necessarily based on "when" it was MFG'd. The most accurate answer is the info printed on your own propeller. Here is what mine has on it ...
Just a Question
Just a question, not a comment:
How much difference is there in the friction between the hub and the prop when you torque the bolts to 38, or 40, or 42 lb/ft. ? As I understand it, the friction is what holds the prop, not the shear of the bolts. That's why the mfg's call out 7" diameter hubs. I stand ready to be corrected.
How critical is this measurement, or are we "measuring with a micrometer and cutting with an axe?"
Just a question, not a comment:
How much difference is there in the friction between the hub and the prop when you torque the bolts to 38, or 40, or 42 lb/ft. ? As I understand it, the friction is what holds the prop, not the shear of the bolts. That's why the mfg's call out 7" diameter hubs. I stand ready to be corrected.
How critical is this measurement, or are we "measuring with a micrometer and cutting with an axe?"
