I dont think they are very hard but it depends on your mechanical knowhow.
******Just make sure you keep presure on the spring**** (a-arm)
loosen the nut that goes threw the spindle but dont take it all the way off most of the time if i use a bar I can pop it off by striking the casting with a hammer then just remove the other three bolts and pull the old one out.
At least thats how I do it