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Old 03-02-2021, 16:01   #1
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Autoprop Rebuild

Purchased a 2001 Beneteau 361 back in June. One thing I noticed was a significant lag when going from forward to reverse. When the boat was hauled out for the winter, found out why. The blades of the Autoprop H5 did not rotate freely.

Neither did the rudder (different post) so while the rudder was off, pulled the prop. Was able to use a Harmonic Balancer Steering Wheel Puller Kit, not the one with the claws. Found bolts that matched the thread pattern of the end cap bolts just longer. MAKE SURE you use bolts that are long enough to almost bottom out. If not you risk snapping one or more bolts in the shaft end which would be really bad.

Here's a video on the removal:



Once removed the disassembly fun begins. Despite other threads indicating the removal of the 3 caps (one per blade) being easy, mine was not. Not at all.
First the moving blades make torquing the caps difficult. So, the prop has to be placed on a bench corner, then clamps applied to hold each blade. Only works on the corner of a bench which will be obvious when trying to do this.

To remove the cap there are four spots to insert a pin to rotate the cap. Bruntons sells an expensive tool to do this, which is essentially a pin spanner similar to what comes with an angle grinder. Picked up one at Harbor Freight and used a pipe for leverage. Unfortunately, there was no way to get this to work. The caps would not budge.
Purchased a 36" piece of bar stock at HomeDepot and four #10 1/2" stainless bolts with washers and nuts. Measured the hole pattern on the caps and carefully transferred to the end of the bar stock. Drilled out the 4 holes (3/16") and installed the four bolts, using washers and the nuts to ensure just the right amount bolt end being exposed to bite on the cap but not bottom out.

Here are the two videos showing the prop service:

Disassembly


Reassembly
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Old 04-02-2021, 06:04   #2
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Re: Autoprop Rebuild

Got everything apart, was not easy but only one busted knuckle so that's a win.

Had ordered the $292 rebuild kit from King Propulsion located in the USA. Can't recommend them enough. Rod responded sometimes in minutes.



Now the bad news. As suspected the single owner of the boat (prior to me) probably never had the prop serviced. It appears that one of the bearing races is marked up and will more than likely have to go back for burnishing by the factory. Will probably send the entire assembly while I'm at it. Sucks but I did save $200 on tools (boat logic ). Should get a service quote shortly.
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Old 04-02-2021, 07:26   #3
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Re: Autoprop Rebuild

Looks like the race has some brinnelling. I believe you could minimize that with fine sandpaper and an easy touch.

The blades are not a true rotating part, the clearances and tolerances are not so critical. Proper bearing adjustment and proper greasing and you should be good to go.
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Old 04-02-2021, 07:52   #4
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Re: Autoprop Rebuild

on Rod a King Propulsion also.

I have 15 years messing with the older H5 bb model inluding a trip back to the factory (postage was tough). I would not worry about the small amount of marking on the race and would not take emery cloth or anything to it. Reassemble with the new kit and try it out.

I think that (we will call it brinelling) on the race is caused by the blades rocking back and forth during use. I put mine up a little tighter than the factory specs but still free to rotate. Would appear to improve the situation. Do get the torque right during reassy, slinging a blade off is not "a make your day experience". I have really liked my AP but it does take some fiddling and tends to wear my Yanmar motor mounts a little quicker.

Frankly

My original is now 25 YO and still working fine (replace bearings every 5 or so years). The races look a lot worse than your picture. Found a replacement on ebay last year(like new). Now I have a spare.
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Old 04-02-2021, 09:08   #5
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Re: Autoprop Rebuild

One other little trick. I have an old worn spare shaft that I clamp on a bench for holding the prop during rebuild and painting. It is a heavy and hard thing to work with as the blades keep flipping around. The shaft mount makes life bearable.


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Old 04-02-2021, 09:52   #6
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Re: Autoprop Rebuild

I have an old Autoprop that needs servicing. I'd be willing to sell it to an interested individual. I will get the specs and post back here shortly but let me know if there is any interest. It was previously on a 47 foot Catalina.
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Old 04-02-2021, 10:43   #7
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Re: Autoprop Rebuild

Quote:
Originally Posted by kenbo View Post
Looks like the race has some brinnelling. I believe you could minimize that with fine sandpaper and an easy touch.

The blades are not a true rotating part, the clearances and tolerances are not so critical. Proper bearing adjustment and proper greasing and you should be good to go.
I will give Bruntons credit, they responded very quickly, requesting the serial number and promising a quote. We'll see what the damage looks like. Bought the boat via auction so I've got nothing to complain about regarding refit costs. So far been extremely lucky with expenses.
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Old 04-02-2021, 11:15   #8
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Re: Autoprop Rebuild

Quote:
Originally Posted by GreenWave View Post
I have an old Autoprop that needs servicing. I'd be willing to sell it to an interested individual. I will get the specs and post back here shortly but let me know if there is any interest. It was previously on a 47 foot Catalina.
What engine/reduction ratio is on the C470 and shaft size?

Thanks
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Old 04-02-2021, 11:35   #9
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Re: Autoprop Rebuild

Quote:
Originally Posted by scfoster View Post
I will give Bruntons credit, they responded very quickly, requesting the serial number and promising a quote. We'll see what the damage looks like. Bought the boat via auction so I've got nothing to complain about regarding refit costs. So far been extremely lucky with expenses.
I've rebuilt a number of those props and that bearing race you showed looked acceptable. A little wet sanding to take the ridges down a bit is fine.

The real secret to making those props run smoothly is balancing the blades. They can't be statically balanced so here's what I came up with and it gives good results. Balance the blades the same way a connecting rod is balanced on a high RPM engine. This video will give you an idea of how to do it , I only remove material from the aft side of the blade.

I also have been using a product called VibraTite instead of Loctite, much more confidence in the ultimate holding power.
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Old 04-02-2021, 11:43   #10
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Re: Autoprop Rebuild

Quote:
Originally Posted by kenbo View Post
What engine/reduction ratio is on the C470 and shaft size?

Thanks

She has a 75hp Yanmar 4jh3-TE engine with Kanzaki transmission. 1.5 inch shaft. Trying to find the reduction ratio as I don't recall and don't have that info at hand off the boat.
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Old 04-02-2021, 11:53   #11
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Re: Autoprop Rebuild

Quote:
Originally Posted by GreenWave View Post
She has a 75hp Yanmar 4jh3-TE engine with Kanzaki transmission. 1.5 inch shaft. Trying to find the reduction ratio as I don't recall and don't have that info at hand off the boat.
Thanks, that's the 3800 RPM engine with a KM4A Kanzaki probably. So I'm guessing a 2.63:1 reduction. If the reduction is 3.30:1 by chance let me know. Otherwise I'll have to pass.
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Old 04-02-2021, 12:34   #12
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Re: Autoprop Rebuild

Quote:
Originally Posted by kenbo View Post
Thanks, that's the 3800 RPM engine with a KM4A Kanzaki probably. So I'm guessing a 2.63:1 reduction. If the reduction is 3.30:1 by chance let me know. Otherwise I'll have to pass.

I am 95% sure it is 2.63:1
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Old 05-02-2021, 16:44   #13
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Re: Autoprop Rebuild

Quote:
Originally Posted by kenbo View Post
Thanks, that's the 3800 RPM engine with a KM4A Kanzaki probably. So I'm guessing a 2.63:1 reduction. If the reduction is 3.30:1 by chance let me know. Otherwise I'll have to pass.



Went to boat today and well, I was 95% wrong... The reduction ratio is 3.3:1


Let me know if there is interest Not sure what it would take to get to your location.
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Old 07-02-2021, 07:21   #14
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Re: Autoprop Rebuild

Agree about the balancing. From the factory the Autoprop assembly is balanced. The hub is marked with each of the 3 blade positions. Each blade has a serial number of the assembly and the corresponding blade position. The blade in the attached picture has a "3" stamped in it.

Ran a brand new ball bearing around the race of each blade. A lot smoother than the image would indicate. If the burnishing quote comes back quite expensive, it probably will, I think I'll attempt to polish a bit and focus on the assembly torque to have each blade fall under its own weight.

Question... how would you polish the race? The diameter is 5mm which is just under the width of a #2 pencil eraser. The surface has to be pretty hard so not sure what would work by hand. Thoughts?
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Old 07-02-2021, 08:08   #15
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Re: Autoprop Rebuild

You could try valve grinding paste and a 3M pad but that brinnelling is so mild you could ignore it.
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