How do you change gmc dually rear brake drums?

to change brake drums , first determine whether vehicle has semi- floating axles or full floating axles. full floating axles have 6 or 8 blots in the end of the axle. semi- floating axles will have no bolts on the end. to remove full floating axle, remove all bolts. (oil will run out when you do this if you havent drained the differential).you will need a large breaker bar.

if axle doesnt come out, give it a good whack with a large hammer. this will break the seal and allow axle to be removed.

on semi-floatrers only, remove spindle nut with large socket.

on full floaters, using screwdriver and needle nosed pliers, remove c-clip and then key stock both of which hold castle nut in place. unscrew nut with screwdriver in one of the slots. you may also need to get under truck and manually back off the brake shoes via access hole in backing plate. with the nut removed you should be able to slide drum off vehicle. bearings will stay in place unless they are falling apart.

to remove semi floating axle, jack up vehicle. drain diff oil,remove inspection plate from rear of differential,and inside you will see a bolt through a metal block. remove both; push axles inwards. then remove c-clips so you can pull them out.

NOTE:keep axles on side of truck where they came out: axles are different lengths and will fit properly only in the correct sides.

when replacing drums, replace seals and bearings as well. make sure they are packed well with proper grease. this is also a good time to inspect shoes and cylinders. if you replace them as well and need to bleed brakes, use a 1/4" flex bar to access bleeder valve.