View Full Version : RAF belt redrives
12-29-2007, 02:52 AM
The standard belt redrive for a RAF, does it generally cause problems with the crank? As i have heard on a few occasions that the EJ 22/25 breaking cranks at the end of the enigne, and nearly all times it had a belt drive sitting on it.
Is there anything that can be done to prevent this?
Just out of curiosity what is the reductuction of these drives please.
What props, size and types do people run with this set up?
12-29-2007, 04:22 AM
It shouldnt, solong as the 'steady bearing' is setup proper.
But a prop strike with a belt drive aint as forgiven as it is on a 912/914.
[ wot the hell are you skeem'n up now bonsey??? :)]
12-29-2007, 06:15 AM
The standard RAF redrive for the 22 is 2.1 with a 68 inch WD three bladed prop. This give about 2595 prop RPM at 5450 ERPM. RAF recommended that a four bladed prop be used with a 2.5 Sub. The extra blade is to compensate for the extra Horsepower.
12-29-2007, 08:58 PM
The bearing in the redrive sprocket is recommended to be changed out for an american made one. The original is a cheap chinese version. There is another website that I dont have the URL for right now that explains it and supplies info for the correct bearing and mod. I'm sure that someone else with this URL will post it for us.
12-30-2007, 09:36 AM
I'm interested in knowing that site as well.
12-30-2007, 04:53 PM
Anatha thing you gota chech out very carefuly if you RAF redrive suffers a prop strike is the alinement of the driveing/driven pullys.
Before i got the wasa it had a minor strike [ prop/ rotor during a bad flap] and i found the first belt i had that came with it was cactus after only bout 50 hours.
I found useing a micromiter that the pullies were fractionaly out of line[ bout 5 th"]. Not much, but enuff to chew the teeth of inside 50 hours.
The houseing was slightly bent from the strike and was fixed with a coke can shimm. ;)
01-10-2008, 07:00 PM
Just remebered. Here's URL mentioned a week ago. I'm sure some of you know it alrready. I believe its Gary K's site.
01-10-2008, 09:00 PM
The belt drive seems to be the culprit bones as I have yet to hear of a broken crank with any other re drive.
Tom did 3,800 hours on his 2.2 with a rotax gearbox
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