As mentioned previously, the ones in the kit are Helical gears. Are these the ones you are talking about or did you use bevel gears for something else?
Anyways, if you are talking about the helicals, I can tell you that we used them this year without any problems whatsoever. The key is to make sure you have spacers that are the correct size inside the gearbox and to make sure the shaft can't "walk" out of the gearbox. Here's some pics of our 'bot, which uses both the Chips and the Drills driving the gearboxes provided by FIRST:
http://www.cogsquad.org/image.php?id=34
http://www.chiefdelphi.com/forums/pi...gle&picid=4614