is it ok for a dust cover of a brake piston worn out? a small part torn out already... is it safe to use it? is so anyone know how to change it? easiest way?

 

it will be ok. run it. eventually the dirt will get to it , but it will take a bit.

 

it can be a pain to put a new seal in. Heres a hack job that may help.

push the piston out with the pedal until the piston seal is almost tight (NO farther or it'll come out.) push the boot down the piston as far as it can go clean the piston itself as well as you can, trying to get all the dirt possible. clean the piston boot as well as you can. heres the hack job part. try and seal the hole. I don't have a lot of advice here. Some have tried electrical tape over it and a heat gun to turn the tape into rubber (I don't reccomend this.) Some have made two rotations with a rubbery electrical tape around the seal, but thats only if the tear is in the right spot. This is a temp fix that will only last so long before dirt gets in again. Of course your best method is to rebuild the caliper with a new piston, but then you have the issue of bleeding, lubricating, etc. then push the piston back in (the boot seal will slip into the piston groove itself pretty much. ) Make sure the master cylinder's cap is off when you push the cylinder back into the caliper to make it easier. If you can't do it by hand, get a C-clamp to help push the piston back in.