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Discussion Starter · #1 ·
So I have replaced my master cylinder and brake lines, and ran DOT 3 through the system, then my brake wouldn't fully release, more like 20% release, 80% stuck. I don't know the state of function before as the bike was a non-runner with liquid crud in the res.



I have removed the caliper and squeezed the caliper piston out quite a bit (forgot to take off the dust cover and ring), and I have a few questions:



1. Should I be able to push it back in by hand if I have taken out the banjo bolt and released the bleeder valve?



2. If yes, I can't. If no, then is compressed air the next route to remove the piston?



3. Does removing the piston sort of "reset" the brake to be able to push the piston back in?



I was thinking of getting a rebuild kit w/piston, do you think the actual caliper itself could be beyond rebuild - rust/crud inside the piston channel?



I'm so close to making this thing road worthy now I can taste it! Oh wait, that's the brake fluid under my nails.



Thanks,



Scrap
 

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Some can probably push the piston in by hand but most often I use a C clamp. Or in my toolbox I have a large c-clamp like vise grip that does it every time.



Once everything is clean and rebuild you should be able to take a lubed piston and push it back in to place.
 

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You need to take the piston completely out, so either keep pulling to get it out, or yes used compressed air thru the bleeder port. BE CAREFUL as the piston will come out hard, watch your fingers!



Once out the caliper should be fine, they're aluminum. Just scrape out all the crap with brushes and dentist picks --- be sure the clean the groove where the seal goes!



Hand polish the piston with some polishing compound or chrome polish, it should clean right up. All you should need is a new seal and maybe dust cover. The calipers and pistons seem to never wear out beyond use, unless there's deep scars in the piston...



Lube the piston and newly installed seal with a little brake fluid and press it in. Good to go!
 

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Discussion Starter · #5 ·
I would like to thank each and everyone one of you who suggested to keep my fingers away from the piston. Holy smokes!



The piston looks like a light polishing will do the trick. The inside of the caliper piston chamber could probably use a little too. I'll look up the "how to polish" thread and go from there.



Much obliged forum members!
 

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Hey Shep,



You make that sound like I'm in for more difficulties. Where is the optimism here? Ha ha. Thanks for the link, no job is ever easy.


Nah.It's just common that once the fluid has been out of the MC people can have problems getting the fluid to flow.Takes me less than 30 seconds using the palm of my hand.5 mins if I have to use the front Banjo bolt method
 

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Discussion Starter · #12 ·
Just a note of thanks to all on this forum, and of course the invaluable resources within it (Thanks Charles!).



I completed my first front brake caliper rebuild/clean and it turned out successful. No more dragging front brake. After reading through the process a few times (and searching out pics) I found the job quite easy.



My advice: if you think you can't do it, try it anyway. If it isn't going well you can always bring it to a shop, but if you find it going smoothly, you may just save yourself $100 in labor.



My only excess spending was the two bottles of brake fluid to get it right. A welcomed trade off in my opinion.
 

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Hope you didn't throw the old brake fluid away?



It's a great paint stripper for small parts left to soak in it.



It's a great Rust release/dissolver and even better as a,"Liquid wrench" if mixed 50/50 with Acetone
 

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Discussion Starter · #14 ·
Hey Shep, good thinking!



I haven't thrown it away yet, so looks like I'll keep it. Besides, you never know when you need to bleed the lines again and I'll already have a place to dip my hose. (Er, that sounded weird).
 
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