although its probably not neccessary i always replace springs same time as i do the shoes....i replace shoes/springs as soon as i notice a change in the engagement/grip...take them out and look for glazing, if its not too bad try taking the glaze of with some real fine sand paper. but with the cost of clutch parts i always jsut get new ones. i have yet to put much wear on my RS4 clutch...but i go through shoes about once every 2-3 times out in my .21 maxx...time for aluminum shoes or better yet a strobe-1/8 bell setup. BTW it may speed up wear a little but i like to scuff up the inside of the bell some for more bite.