View Full Version : Re-build Calipers & Master Cyl's [?]

6th February 2005, 03:50
I have not yet re-built the brake calipers and master cylinders on any of my bikes. Always shyed away from these tasks since they "seem complex" and were not apparently necessary. Also the FM advises "Do not re-build m.cyls unless you are experiencing problems" and Clymer advises to use compressed air carefully to blow out the pistons.

Well, this bike is 25 years old and i kinda think these jobs should be done. And that i should do them myself. And winter project time seems like a good time.

Any comments or suggestions before i begin would be appreciated. I have the FM and the Clymer to follow.


6th February 2005, 23:40
hey mick that shouldnt be a problem for you. the calipers are easy to do as far as the masters I havnt done mine yet but they may not be to bad.Back to the calipers you use shop air to pop them apart. lay caliper on the bench take a shop rag and fold it over slip it in between opening below piston apply air to caliper through opening from brake line piston will come out may require a few shots of air.Once its out inspect piston for nicks or scoring also the bore of caliper. remove old seals clean pieces up install new seals lubing with dot 5 the piston may reguire a bit of fiddling to install but it will go.After rebuild and install on bikebleed brakes by pumping dot 5 up from caliper to master cyl.It sounds backwards but it works real well.Use a large sryinge or a clean pump oil can. long story but if you have the manual its easy done
hope this helps good luck

7th February 2005, 00:19
I don't have compressed air in my shop. I guess i can take them to a local inde to get the pistons out; unless there is a way ...

7th February 2005, 00:45
I don't have compressed air in my shop. I guess i can take them to a local inde to get the pistons out; unless there is a way ...
thats what you will have to do then .when I did mine it took quite a bit to pop them out.you may be lucky if you can twist them and pull at the same time.the guy that did mine before I got the bike did that and scratched the hell out of the pistons :eek:

7th February 2005, 02:32
I rebuilt the front master cyl. on my 79 a few years ago and it was pretty easy. Just follow the manual.

7th February 2005, 02:39
mick , do you have an air tank ? not one with a pump but just a storage tank , you can fit a blowgun to that and use it

if ya don't have one , you can get them at a parts store for around $30 bucks U.S. and they do come in handy for flat tyres and such, you won't run air tools with it but you can run a small paint gun

just fill it at your local gas station

15th February 2005, 20:06