Yamaha Phazer - Rotax Gearbox Adapter

20 posts in this topic

Posted (edited)

I see more guys using the Phazer engines but nobody seems to get into the details of making the adapter so I will take a shot at it.  I have been collecting parts and working on the design for a while and I finally got my adapter setup.  I still need to get shorter bolts to hold the gearbox to the adapter plate.  I plan on eventually replacing my 582 with this Phazer engine.

I machined the engine cover so that all the tabs where the bolts go through are all the same height and replaced the bolts that hold the bearing with cap screws.  The heads of the screws locate the plate and align the gearbox mounting holes with the output shaft.

I made spacers to compensate for the height difference between the output shaft and engine cover bolt tabs.  Longer bolts were also needed.

Some 1/2 aluminum plate came from the cutoff pile at the local metal supply shop.  Lots of time was spent adjusting the plate on Solidworks and printing it on paper to get it just right and then I milled a test piece out of wood and then one out of aluminum.

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You can see the uneven gap between the 4 bearing bolt holes and the large hole for the output shaft.  I had an issue with the part moving between drilling all the small holes and milling the large holes.  I am very confident in the position accuracy of the small holes.  Although the large holes are slightly off, they still provide enough clearance to serve their purpose.

Edited by Tom.338
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Posted (edited)

I am planning to use a RK400 clutch so I had to trim the engine output shaft and shorten the gearbox.  There was no room for a locating ring like on the 582 so I located the gearbox with 2 dowels instead.  I used two of the bolt holes that do not enter the gearbox for the alignment to avoid having any oil leaks.

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Edited by Tom.338
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Posted

The RK 400 fits in a pocket in the plate and 2 of the engine cover cap screws fit into counterbored holes so that the surface of the plate is flat where the gearbox mounts.

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Posted

The gearbox is tilted to align with the center of the engine and to allow the gearbox and engine cover bolts to have clearance.

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Posted

I have another piece of 3/8 plate that is longer so I will probably make another adapter that can reach the 2 engine cover bolts I missed with this one.

Thanks to 72chevy for leading the way.

Let me know what you guys think or if you have any questions.

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Posted


Nice work keep it up.

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Posted

All looks good but, from what I’ve heard with the RK gearbox the alignments have to be spot on!!!

if this works, I’d be interested in one for my sky raider

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Posted

YES, i would also b interested in one of those setup, i want to replace the grey 582 in the bluefox with the phazer motor. Been lookin for a yammy phazer already. 

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Posted

There is a guy in michigan that used a phaser on a kolb and he has made the phaser engine management system work for the plane with a software change of some kind >>> 

>  https://www.youtube.com/watch?v=wqEtXWT39HU

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Posted (edited)

All looks good but, from what I’ve heard with the RK gearbox the alignments have to be spot on!!!

 

The alignment was a major concern for me.  I took the shoes out of the clutch and put spacers on the 4 corners to center the taper on the inner part of the clutch in the outer drum.  Then I put that in the gearbox on the splined shaft and measured the runout in the taper at 0.0025" I put the clutch on the tapered engine output shaft by itself.  Then I put the gearbox on without the splined shaft to see, when everything was mounted, if the splines would engage and show me that everything is aligned.  The splined shaft fit into the bearing and I rotated it until the splines lined up and it slid the rest of the way in.  I think the alignment is within an acceptable tolerance but I will know for sure when I get it on a test stand.

I was thinking of how I could test the alignment and this was the best idea I could come up with.  I would have liked to have zero runout with my spacers but 0.0025" is pretty good and the dial indicator was on an angle so it is actually a bit less than that.  Any tolerance issues with the spline will be there in the final product so it seemed like an acceptable test.

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14.thumb.jpg.ebbfe752d2c32b200a73ad8ab6dThe splines don't look centered in the bearing because of the camera angle.

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Edited by Tom.338
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Posted

Way to go!  Yeah we have about 4 people now taking on custom cbox plates for the Phazer.  Most are waiting for the Skytrax gearbox which is available for pre-order, but some prefer the cbox and rk400 for good reasons.

And yep alignment is critical.  Looks like you are on top of that issue.   As a rule If your rk is making dust then you are off a bit too much. 

Everyone who has done a plate has had to do a little adjusting to get it aligned just right, then normally a gearbox indexing shoulder on the plate is necessary because the "wiggle" tolerance of the mounting bolts on the flat plate is too sloppy.   Gotta lock the gearbox in place on the plate.

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Posted

Thanks for the tip about watching for dust.

I am hoping the 3/8" pins will be enough to stop the wiggle but I will have to see.  I think I will try to make a locating shoulder on the next one.

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Posted

Whoops I see there in post #2 your dowels and the gearbox cut.  Missed that first read through.

Bet that will lock it in place just fine. 

Looking forward to watching this Yamaha build!

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Posted

Locating shoulder will be great, seaplanes benefit greatly with the use of the clutch, remember, we don’t have any brakes,When the engine starts ,where in motion!!!

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Posted

Yeah I love the rk on my rx1 kf5 floatplane!

Great for the cold winter starts / warmups too!

In talking to Teal he is planning a full end housing adapter plate for the Phazer to fit a c/e box in the up or down position.  It is on the "to-do" list of his.

And as far as the shoulder,  338 I can see your fab abilities here and am jealous!   I'm sure you don't need my 100 level input but will throw out the idea of an exterior locating profile (since there's not room on the interior with the clutch drum so close)

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Posted

The easiest way I figured out to keep everything centered dead nuts and repeatable was to mill a bit off the gear cover to expose enough of the pto bearing to center off of.

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Posted

Remove the material at this location. The sealing  Oring on the pto bearing will likely become exposed but your favorite gasket maker can take its place, a sealant will also need to be used on the pto bearing bolts since they go to oil. 
  Your adapter plate should have a light press fit over the bearing, you will also need a step on the face of the adapter plate that will have a light press fit inside the bore of the gearbox. 

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Posted

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Posted

Those are the best photos I’ve got of how I did my adapter, obviously there is more than one way to skin a cat, it’s great to see others figuring this out and going for it.  The bottom picture is the clutch drum after my initial engine testing, no wear or clutch dust.

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Posted

Nice idea using the bearing to locate everything.  I like that design and it looks like everything is working nicely in the videos.

Now I think I might have been better off machining on the engine side rather than the gearbox side of the plate to get the plate to sit lower like yours and have more room for a shoulder.  My gearbox is too short to change it now but it's something to think about if someone is still coming up with a design.

 

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