2007-2009 Honda TRX300EX TRX300X service manual, Page 287Get this manual
HYDRAULIC DISC BRAKE Check the brake disc for warpage SERVICE LIMIT: 0.30 mm (0.012 in)
Check the front wheel hub bearings or rear axle bearings for excessive play, if the warpage exceeds the service limitReplace the brake disc if the bearings are normalFor brake disc replacement: front brake (page 13-18) rear brake (page 14-6)
FRONT MASTER CYLINDER
DISASSEMBLY
Drain the brake fluid from the front brake hydraulic system (page 15-6)When removing the oil bolt, cover the end of the hose to prevent contamination