Prop hub spacer

[mack55]

I believe that I have the wrong propeller bushings in my O-360 A1A crankshaft. Unfortunately, I didn’t realize this until I went to mount the propeller. Parts list calls for
4X 72062-s length = .780”
1X 72061-s length = .590
1X 72060-s length = .590

mine are about 0.100” too long when the fly wheel is installed

The way I see it there are 2 options.
1. Install the correct bushing part numbers listed above. Question is can this be done with the engine assembled. I don’t believe I have the required clearance from the back of the crank flange to the engine case to remove and replace.

2. Make a spacer that’s 0.100” thick. I have one that’s 0.250” that I could have someone mill down. Any issues extending the prop out 0.100” further forward? Sealing issues?

Thoughts?

 

[rvbuilder2002]

I believe that I have the wrong propeller bushings in my O-360 A1A crankshaft. Unfortunately, I didn’t realize this until I went to mount the propeller. Parts list calls for
4X 72062-s length = .780”
1X 72061-s length = .590
1X 72060-s length = .590

mine are about 0.100” too long when the fly wheel is installed

The way I see it there are 2 options.
1. Install the correct bushing part numbers listed above. Question is can this be done with the engine assembled. I don’t believe I have the required clearance from the back of the crank flange to the engine case to remove and replace.

2. Make a spacer that’s 0.100” thick. I have one that’s 0.250” that I could have someone mill down. Any issues extending the prop out 0.100” further forward? Sealing issues?

Thoughts?

Why are you using a thin spacer to space the prop forward?
The drive lugs in your crankshaft are not too short. Any propeller or propeller extension is supposed to have counter bored holes that fit over the bushings.
The bushings are what drive the rotation of the spacer or the propeller. Not the bolts.
The bolts are only there to hold everything together.

 

[mack55]

Why are you using a thin spacer to space the prop forward?
The drive lugs in your crankshaft are not too short. Any propeller or propeller extension is supposed to have counter bored holes that fit over the bushings.
The bushings are what drive the rotation of the spacer or the propeller. Not the bolts.
The bolts are only there to hold everything together.

My bushings are 0.100” too long. There are supposed to be 2 flush ones and then 4 that extend .180 - .200

 

[rvbuilder2002]

I agree that two of the bushings should be flush with the forward face of the ring gear support, but the other four look like they are correct.
If you install a spacer to make the short ones flush, it looks to me like you will have much less than normal engagement on the four long ones.
Is this possibly an older engine with a thin crankshaft flange? (I think they also have lightning holes in the flange between each drive lug)
If so, they weren’t really designed for use of a constant speed propeller.

 

[penguin]

It is straight forward to change the drive lugs, call Saber manufacturing and discuss your options, they can also sell thin spacers.
I would also call your prop manufacturer, is a Whirlwind, or perhaps you engine overhauler? Something doesn't look quite right, there are generally only 2 lengths of drive lug with fixed pitch props requiring much longer lugs. You definitely don't have FP lugs.

 

[mack55]

It is straight forward to change the drive lugs, call Saber manufacturing and discuss your options, they can also sell thin spacers.
I would also call your prop manufacturer, is a Whirlwind, or perhaps you engine overhauler? Something doesn't look quite right, there are generally only 2 lengths of drive lug with fixed pitch props requiring much longer lugs. You definitely don't have FP lugs.

Thanks for the guidance. Called Saber Manufacturing and have new lugs on the way. This engine was used in a Pitts with a FP prop. Used a .250" spacer in place of the starter ring gear. Now I hope I don't have any issues removing and installing them with the engine assembled...

 

[mack55]

I agree that two of the bushings should be flush with the forward face of the ring gear support, but the other four look like they are correct.
If you install a spacer to make the short ones flush, it looks to me like you will have much less than normal engagement on the four long ones.
Is this possibly an older engine with a thin crankshaft flange? (I think they also have lightning holes in the flange between each drive lug)
If so, they weren’t really designed for use of a constant speed propeller.

Thanks for the input. I ordered the correct bushings. Hopefully back to the cowl fitting next weekend.

 

[penguin]

>Now I hope I don't have any issues removing and installing them with the engine assembled...

It is straight forward using 2 sockets and large G clamp, plenty of room with the engine installed.