Gears in the gearbox change

[BryceKat 125]

Has anyone changed the gears in a c box from 3:1 to 2.6:1 ? I'm thinking I'll get better climb performance, especially with the Ifo. Thoughts? Bryce

[akflyer 1427]

Has anyone changed the gears in a c box from 3:1 to 2.6:1 ? I'm thinking I'll get better climb performance, especially with the Ifo. Thoughts? Bryce

I swapped them back and forth a couple times to see what the difference would be. With the IFO it is kinda negligible with a slight edge going to the 2.62:1 gears from my testing. Granted, my testing was not with a scale and a pull test as I had originally wanted to do, but a get off the water and out climb the trees test..

[akflyer 1427]

Just quick math, your talking about a 316 RPM difference at the prop at 6500 RPM on takeoff (the max HP RPM) While your turning the prop higher, your doing it at less pitch so you get a slight advantage of pulling, but loose on speed as you cant quite hog in as much pitch at cruise. For me, its all about getting off the ground and climbing not about cruise, even though I get a bit of that back with the IFA prop.

Edit* When I talked to the guys at IVO they told me that I would get more pull with the 3:1 so that was what made me try it to begin with. I think that on a slow mover like a PPC it MAY help them, but we have to think about airspeed as well as climb and speed does help = climb in our planes too..

[BryceKat 125]

Leni,

I have an in flight adjustable so I can make up the difference on the top end. Which gears did you stick with? Thanks, Bryce

[akflyer 1427]

Leni,

I have an in flight adjustable so I can make up the difference on the top end. Which gears did you stick with? Thanks, Bryce

After months of playing with them and swapping back and forth I went back to the 2.62:1

[BryceKat 125]

Leni,

When you were testing them, would the temp have been above 70? I noticed the real performance increases come at higher density altitudes. My fixed pitch prop and ifa do about the same climbing below 60-70 degrees, but its night and day above that. Thanks, Bryce

[akflyer 1427]

Leni,

When you were testing them, would the temp have been above 70? I noticed the real performance increases come at higher density altitudes. My fixed pitch prop and ifa do about the same climbing below 60-70 degrees, but its night and day above that. Thanks, Bryce

I started playing with the gears in the spring so it was probly mid 30s to mid 40s, then in the summer when it was in the high 70s low 80s, then again in cool temps in the fall. For the most part I am flying sea level to 5000' with most landings n take offs not much over 3500'

[1avidflyer 1983]

Bryce, I was just looking on Barnstormers, and saw a new set of 2.62 gears for sale. He says make an offer. Only problem is they are in New Zealand.... They probably weigh less than 2 lbs, so shipping shouldn't be to bad. Also, there was a new E box with 2.62 gears in it for $1500. A bit steep just to do some experimenting, but then who ever said anything about aviation was cheap? Take care, Jim Chuk

[BryceKat 125]

Bryce, I was just looking on Barnstormers, and saw a new set of 2.62 gears for sale. He says make an offer. Only problem is they are in New Zealand.... They probably weigh less than 2 lbs, so shipping shouldn't be to bad. Also, there was a new E box with 2.62 gears in it for $1500. A bit steep just to do some experimenting, but then who ever said anything about aviation was cheap? Take care, Jim Chuk

Thanks Jim! What do you think would be a fair price for the gears? Bryce

[1avidflyer 1983]

Not sure, but I just looked at Leading Edge's price from about 5 years ago, and the set was $520. OUCH! I think when people say make an offer, they maybe still kindof have an idea what they might want. Maybe the guy in New Zealand will come up with a price himself if pressed on the issue. The other thing you could do is run a wanted add on Barnstormers. A call to Steve Beaty at Airscrew Performance might get you a set also, but when I talked to him a few years ago about this, he said the 2.62s were harder to find than the 3-1 sets. Take care, Jim Chuk

Thanks Jim! What do you think would be a fair price for the gears? Bryce

[BryceKat 125]

Thanks Jim !

[BryceKat 125]

Hey Leni,

What special rotax tools and parts other than the gear set and gasket for the gear box do I need to swap the gears. Thanks, Bryce

[BryceKat 125]

Hey Leni,

What special rotax tools and parts other than the gear set and gasket for the gear box do I need to swap the gears. Thanks, Bryce

[akflyer 1427]

Hey Leni,

What special rotax tools and parts other than the gear set and gasket for the gear box do I need to swap the gears. Thanks, Bryce

Sorry, I was out of the loop for 3 weeks and didnt see this one! You need the gear puller for both the large and small gear, and you need to make a fixture to hold the prop flange while you put the longest darn cheater bar on the nut and break it loose. It will take a little heat to get the red locktite to break loose. I think I have the acticle from CPS on the computer about doing the gear change... if not, I think Mike had put the articles in the back of all the CPS catalogs... If you dont have one of those, do a google search for "the proper care and feeding of you rotax 2 stroke" I thik that was the name of the series of articles he wrote.

[akflyer 1427]

I got lucky and found it on my computer!

part 55.pdf

[BryceKat 125]

Leni,

Thanks!!! Bryce

[Guest]

I got lucky and found it on my computer!

That is a great document! I have also posted the full 582 service manual somewhere on this and the yahoo site. It also has detailed instructions on gearbox setup.

ChrisB

[akflyer 1427]

I have some more, very relevant articles from Mike on the 2 stroke engines. I will try and get those posted up tonight when I get back to the room.