New Prop install question ... |
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damonwells
Groupie Joined: June-13-2006 Location: United States Status: Offline Points: 87 |
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Posted: August-12-2013 at 5:14pm |
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I just installed a new prop and hopefully properly used lapping / grinding compound. What is a good trick to hold the shaft in place without spinning while rotating the prop back & forth with forward pressure until there isn't much grit left to the compound ? Thanks, cheers, John
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ArtCozier
Platinum Member Joined: April-25-2012 Location: Orlando FL Status: Offline Points: 1023 |
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Maybe I'm a careless boat mechanic, but I betcha over the 49 years that I have messed with inboard boats, I've probably installed a thousand props, and, except for an unlimited hydro (9000 RPM) I've never lapped a prop to the shaft. I have occasionally used Dykem Blue to see whether there is a high spot if there was a vibration problem.
Art |
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"Art"
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boardersdad
Senior Member Joined: June-18-2013 Location: Wisconsin Status: Offline Points: 409 |
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boardersdad
Senior Member Joined: June-18-2013 Location: Wisconsin Status: Offline Points: 409 |
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btw, I lapped my prop onto the shaft and I'm happy I did. Really improved the contact on the taper, which is what transfers all the propeller force to the shaft.
Steve |
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damonwells
Groupie Joined: June-13-2006 Location: United States Status: Offline Points: 87 |
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Thanks Steve ... I have and used that article, excellent. Perhaps I missed it, but I didn't see anywhere in there a good suggestion on how to keep the prop shaft spinning while lapping ? Cheers, John
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baitkiller
Platinum Member Joined: October-11-2011 Location: SW Florida Status: Offline Points: 1693 |
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Take a short line and tie a figure it around the shaft coupling and across 1 or both mounts. Its not allot of torque. i have a shaft zinc on my boat so that gave me some purchase with a pipe wrench.
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Jesus was a bare-footer.............
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boardersdad
Senior Member Joined: June-18-2013 Location: Wisconsin Status: Offline Points: 409 |
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Sorry, John, I forgot about the article below, which I had reviewed. He says, "It helps if you have locked the gear box into gear." As baitkiller said, there's not a lot of torque involved in lapping the prop.
When you tighten the prop nut, you want to use a block of wood or a strap wrench. Lap Fitting A Propeller To A Shaft btw, you said, "until there isn't much grit left to the compound". I don't think you need to do that. I needed 9 or 10 lapping revolutions to improve from about 66% contact to 85% to 90% contact (checked with Prussian blue). See this thread. The lapping compound I wiped away at the end still felt gritty. As it says in the article, you don't want to overdo it. Steve |
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8122pbrainard
Grand Poobah Joined: September-14-2006 Location: Three Lakes Wi. Status: Offline Points: 41045 |
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This only works with a manual trans. Most here have hydraulics which need the engine running to develop pressure to lock up ether of the clutch packs. |
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damonwells
Groupie Joined: June-13-2006 Location: United States Status: Offline Points: 87 |
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YUP, in gear and engine not running, shaft spins !
Perhaps I need to invest in a strap wrench, Rigid Tools looks like they make a nice one. Thanks again, cheers, John |
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ArtCozier
Platinum Member Joined: April-25-2012 Location: Orlando FL Status: Offline Points: 1023 |
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Couldn't you just put a pair of vise-grip pliers on the head of each coupler setscrew and let the handles bear against the bottom of the boat? Or put a large C-clamp on the coupler in such a way that it locks up the shaft.
Just remember to remove it before you go to run the boat! It's a boat, not the space shuttle! Art |
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"Art"
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phatsat67
Grand Poobah Joined: March-13-2006 Location: Indiana Status: Offline Points: 6157 |
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Get a buddy and one of those rubber style wrenches around the shaft or coupler?
Pete is a lapper guy.(Not that there's anything wrong with that! Seinfeld fans haha). I am a if it is smooth when I install it then its fine kinda guy. If shaft run out checks out and a vibration is still present with a new prop lapping would be something I would do. |
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boardersdad
Senior Member Joined: June-18-2013 Location: Wisconsin Status: Offline Points: 409 |
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That's right, Pete, I forgot about that. |
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8122pbrainard
Grand Poobah Joined: September-14-2006 Location: Three Lakes Wi. Status: Offline Points: 41045 |
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I have clamped a couple pieces of wood on the shaft. Remember if a ARE shaft is installed, it does not use the big sq. head set screws. No, we aren't building the space shuttle but, a proper taper fit is a basic mechanical engineering principle. |
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damonwells
Groupie Joined: June-13-2006 Location: United States Status: Offline Points: 87 |
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THANKS everyone for the excellent suggestions ... cheers, John
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