Im ready to do a brake shoe replacement on my 2005 Yamaha Bruin 350 2WD, but I cannot get the castle nut loose on the axle to remove the brake drum housing. I have tried everything short of a 1" impact!! Can someone tell me a secret for this, and also is it possible that this is a left hand thread?  Thanks all for your help  

I just did this on the Big Bear.  If the Bruin has the same solid rear axle setup as the Big Bear, you can put a pipe wrench on the exposed axle shaft on the left side of the ATV.  Use a shop towel between the pipe wrench and the axle to avoid scratching the axle (much), if that bothers you.  Then use a breaking bar on the nut.  You can put a pipe on the wrench handles for extra power if needed. On mine, the threads were standard right hand thread.  Good luck.