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Turning redrive 180 degrees

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buzzypeterson

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Sep 23, 2010
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160
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Wausau, WI USA
Hi guys, I just aquired a rotax 277 right out of a rebuild shop that I trust. It came with the redrive facing down. I want the redrive to point up so that I don't have to hang my engine upside down. How do I make this change and is it something that I can do myself or is it a difficult job?
 

stevel

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Feb 2, 2012
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113
Location
Camarillo, California
You have to split the gearbox to get to the four mounting bolts that attach it to the adapter plate. Then all you have to do is flip it, re-attach it, swap the positions of the drain-plug and the breather, and re-assemble it. Worst case scenario, you have to replace the o-ring between the back half of the gearbox and the adapter plate and/or the gasket between the two case halves.
 

Aviator168

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Sep 21, 2012
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Location
Brookville, NY. USA
You have to split the gearbox to get to the four mounting bolts that attach it to the adapter plate. Then all you have to do is flip it, re-attach it, swap the positions of the drain-plug and the breather, and re-assemble it. Worst case scenario, you have to replace the o-ring between the back half of the gearbox and the adapter plate and/or the gasket between the two case halves.
Just make sure the gearbox don't block the air flow to the cooling fins. I think your best bet is still by mounting the engine up side down. It is a two stroke.
 

don january

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Feb 10, 2015
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Midwest
you must be dealing with prop on or near the thrust line and motor mount? Do like "stevel" Post #3 say's and you should be good to go. good luck Don
 

lake_harley

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Jan 4, 2007
Messages
967
Unless your 277 is different than mine (and I guess that's possible), it's more involved than just "flipping" the gearbox and bolting it back up. Mine had a "narrow" pair of bolts, and a "wide" pair that mount the gearbox to the crankcase. On an "up" gearbox (prop hub in front of the cylinder), there's a spacer betwen the gearbox and the cankcase about 5/8" thick with studs that swap the bolt pattern so the box can be flipped. It requires using a long crankshaft gear. If you have a "down" box now, the gearbox is bolted directly to the crankcase and uses a "short" crank gear.

If this issue had come up about two years ago I would have swapped parts with you. I had an "up" gearbox and needed a "down" gearbox but couldn't find a short crankshaft gear. I ended up using a 4-belt redrive I had instead.

Good luck.

Lynn
 

wakataka

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May 1, 2013
Messages
94
Location
Redding, California
I'm thinking that the standard A gearbox on a 277 won't clear the back of the cylinder in the up position, but I really don't remember. If you can confirm by looking at it that there is enough clearance, then you just remove the four bolts that hold the box to the engine and flip it around to the up position. You may need to replace the gasket, or you may get lucky and have the old one not leak. Beware that if you're running a free-air engine, the gearbox in the up position will block a lot of the airflow around the cylinder.
 

wakataka

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Joined
May 1, 2013
Messages
94
Location
Redding, California
Unless your 277 is different than mine (and I guess that's possible), it's more involved than just "flipping" the gearbox and bolting it back up. Mine had a "narrow" pair of bolts, and a "wide" pair that mount the gearbox to the crankcase. On an "up" gearbox (prop hub in front of the cylinder), there's a spacer betwen the gearbox and the cankcase about 5/8" thick with studs that swap the bolt pattern so the box can be flipped. It requires using a long crankshaft gear. If you have a "down" box now, the gearbox is bolted directly to the crankcase and uses a "short" crank gear.

If this issue had come up about two years ago I would have swapped parts with you. I had an "up" gearbox and needed a "down" gearbox but couldn't find a short crankshaft gear. I ended up using a 4-belt redrive I had instead.

Good luck.

Lynn
It's coming back to me now. Lynn is right. There was an adapter and a different pinon gear required to mount the box in an up position.
 

lake_harley

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Jan 4, 2007
Messages
967
I appreciate the confirmation of what I thought was correct advice. I'll also offer that engine rebuild advice given by wakataka is sound advice! The 277 powered MiniMAX I built hasn't flown yet, but the engine I refreshed with the help of wakataka's input has run many hours now in test runs and taxi practice!

Lynn
 

buzzypeterson

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Sep 23, 2010
Messages
160
Location
Wausau, WI USA
So we all think it needs an adapter? It sounds like that was the consensus right? Where does someone find an adapter and long gear, The plane is a sky raider. It has a 277 engine mount. I could flip it over but the manual shows it cylinder up. Is it possible the adapter in on it with the box down?
 

lake_harley

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Jan 4, 2007
Messages
967
One source to try is Airscrew Performance in Arizona (I think that's the name and location). Gentleman's name is Beede, or something like that. I was looking for parts to go "the other way" so to speak, and he didn't have a short gear, but possibly he has a long gear and the adapter/spacer? It's worth a shot. Another company I did business with is South Mississippi Light Sport Aircraft (again not sure on the exact company name). They rebuilt a 582 for me and my partner for our Kitfox. They talked like they maybe also have some long-forgotten Rotax parts on some shelves.

I'd try to give contact info but I'm on vacation and am about 5 minutes from shutting down my laptop to catch a plane home. BTW....Cancun was nice......and a whole lot warmer than Missouri was this past week.;)

Lynn
 

buzzypeterson

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Sep 23, 2010
Messages
160
Location
Wausau, WI USA
Do you still want to go the other way? I found an adapter plate but need the longer gear. Maybe we can help each other out!

another quick question. How do I tell what gear ratio I have, I don't see anything stamped on the case.
 

buzzypeterson

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Sep 23, 2010
Messages
160
Location
Wausau, WI USA
I'm assuming I have the short gear that you are looking for in there. We would have been in Mexico right at the same time as you but father in law had a heart attack. Luckily we live in wisconsin and with all the cheese curds, brats and sausages everyone eats around here the heart surgeons get lots of practice. He's going to be fine. Always wanted to go to mexico, maybe next year :( The only place I've been out of the country was china, had a job as a pilot and factory contractor for Zenith over there. No small airports, things got a bit interesting at times. We had an appolo fox (kitfox clone) over there, best darn plane I ever flew. 200 kilometers an hour. Nice handling. The zeniths although ugly were good for over there, lots of power lines and no one drives well on the roads you gotta land on. They get down and up fast, although so did the fox.

I'm building a sky raider, little single seat kitfox. But has flaps and ailerons.
 

lake_harley

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Joined
Jan 4, 2007
Messages
967
I would have been happy to do some parts swapping, but I sold off all of the "extra" 277 Rotax parts I accumulated in the process of getting my MiniMAX built. The initial engine I bought, and ended up selling last summer, was exactly what I think you need. It was a free-air 277 Rotax with an "up" gearbox and 60 X 28 wood prop. If time is on your side, maybe you can do like I did; keep looking on various forums and places like barnstormers.com and be patient. I had ended up with 4 engines and a lot of extra parts by the time I was done "collecting", but I finally put together a engine/redrive/prop package on the cheap.

Sorry to hear about your Father-In-Law and not being able to make your trip to Mexico. Unlike the travel brochures that feature "beautiful" people, the crowd at our resort was a by-pass surgery doctor's dream. Mid to late January turned out to be a bit cooler than I would have liked, but the prices at the all-inclusive resorts go up substantially when you get into February. We were there 1 week and even though we came back to temps in the low 30's in Missouri I was glad to be home and back to my shop, toys and projects.

If I stumble across something that might help I'll try to remember to post back or send you a PM.

Lynn
 

texas-buzzard

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Jun 24, 2005
Messages
173
Location
san angelo, tx
It sounds like you have the early A box since it does not have the g/r stamped on the front of the case. It probably has a bolt securing the prop hub to the shaft. The newer box has a one piece hub/shaft and also has more clutch spring washers to handle heavier prop mass. Your g/r can be calculated by comparing the 360 deg of hub rotation to deg. of crank rotation.

Monte
 

buzzypeterson

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Joined
Sep 23, 2010
Messages
160
Location
Wausau, WI USA
I'm thinking were just going to go inverted for now. Maybe upgrade to a bigger engine later. I have enough on my plate if I want this thing flying by spring. No sense I'm making more. I appreciate all the advice though guys!
 
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