Giles 2 #1 Posted April 9, 2011 A few years ago, I owned a Gilson lawn tractor with a 16HP Briggs engine. During an engine rebuild, I discovered the flywheel key was 3/16 ALUNIMUM This particular machine was "shaft driven" with the drive shaft connected to the flywheel. The taper of the crank to flywheel plays a big part in keeping the flywheel from moving. For this reason--always make sure this taper is clean and in perfect condition --even if you have a steel key. Share this post Link to post Share on other sites
theoldwizard1 2 #2 Posted April 9, 2011 B&S used aluminum keys on many engines. If the engine stopped suddenly, the flywheel would shear off the key and not the end of the crank ! Many "no starts" on old B&S engines are because the key is sheared, the flywheel has moved relative to the key way and the timing is off ! Share this post Link to post Share on other sites
rmaynard 14,864 #3 Posted April 9, 2011 If you go to the Brian Miller's pulling tractor website, he recommends aluminum (4041 hardness) keys for all engines. Share this post Link to post Share on other sites
Gene_S 93 #4 Posted April 9, 2011 I'll take a sheared key over a broken crank any day!!! I've fixed many of push mowers that have hit all kinds of stupid stuff and then the owner throws it away thinking its shot. I throw a new key in, bend the blade back or replace and bam you got a new to you push mower... :wh: Share this post Link to post Share on other sites
