04 kodiak 400 broken backplate on rear drum
 

the back brakes on my buddies kodiak quit workin so i tore into it to find that the backplate of the drum brakes is cracked on the bottom probably from hitting a rock. the backplate is very thin and i can see this happening again. it's not cracked on the part where the rubber o-ring seal sits in the groove. theres a good 3/8" past there but aperently it still leaked like a seive.
can you buy a guard to put on the drum brake housing to keep it from getting broke if we replace it. otherwise i'm gonna go with a new seal and use silicone gasket sealer around the cover when i put it back together. is there any reason why i couldn't use it? should i replace the axle seal on the cover? do these seals leak regardless after a while or was it probably leaking where the backplate is cracked becuase the cover wasn't held tight enough becuse where the backplate was cracked one of the bolt holes that holds the cover on was there?