---------------------------------------------------------- Kitfox-List Digest Archive --- Total Messages Posted Sat 09/25/10: 2 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 07:26 AM - Re: props and engines (Roger Lee) 2. 07:42 AM - Re: props and engines (mikeperkins) ________________________________ Message 1 _____________________________________ Time: 07:26:52 AM PST US Subject: Kitfox-List: Re: props and engines From: "Roger Lee" Hi Ed, Props, hubs, spacers and all the nuts and bolts forward of the prop flange are not in balance. They all play a part and every prop assembly before going on a plane should balanced. Everyone only thinks they should just check the prop, but there is more attached to that prop. You can get a nice prop and wheel balancer for about $125 and it is so easy to use a "Caveman could do it". I balance everything in front of the prop flange except the spinner. They are all off. You can use a standard washer on a bolt for the balance change. At the minimum a full prop assembly should be static balanced. I also have a Dynamic balancer that I use. I know most don't have a dynamic balancer, but you can seek out someone who has one. The other thing that causes these types of vibrations is a poor carb balance or none at all. make sure the carbs are balanced. A lot of time on the gear box (over 800 hrs) will cause this because the bellville washers become weak and the friction torque on the gearbox gets low. If you have questions you can call me. Roger Lee Tucson, AZ 520-574-1080 -------- Roger Lee Tucson, Az. Light Sport Repairman - Maintenance Rated Rotax Repair Center 520-574-1080 Read this topic online here: http://forums.matronics.com/viewtopic.php?p=313697#313697 ________________________________ Message 2 _____________________________________ Time: 07:42:31 AM PST US Subject: Kitfox-List: Re: props and engines From: "mikeperkins" As we've talked before, Ed, you might remember that I go back to the "Denny Days" of '86-'87. I recall quite well that the entire reason Denny specified a three-blade prop on the two-cylinder engines was to prevent harmonic vibration, regardless of the gear ratio. Where there is vibration, there is also fatigue. Minimizing vibration: Static balance, checked with bearings and shaft on a bench, 1 gram Pitch, checked with a protractor, 1/4 degree Dynamic balance, checked with a dynamic balance instrument, zeroed Static tracking, checked with a stick in the ground, 1/8" max Dynamic tracking at RPM, checked visually by ground-running the engine, 1/8" max. Carb balance, checked with a flowmeter. (I have one if you want to borrow it). Mike Perkins Read this topic online here: http://forums.matronics.com/viewtopic.php?p=313700#313700 ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message kitfox-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/Kitfox-List.htm Web Forum Interface To Lists http://forums.matronics.com Matronics List Wiki http://wiki.matronics.com Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/kitfox-list Browse Digests http://www.matronics.com/digest/kitfox-list Browse Other Lists http://www.matronics.com/browse Live Online Chat! http://www.matronics.com/chat Archive Downloading http://www.matronics.com/archives Photo Share http://www.matronics.com/photoshare Other Email Lists http://www.matronics.com/emaillists Contributions http://www.matronics.com/contribution ------------------------------------------------------------------------------------- These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.