Bleeding brakes and master cylinder

[PasoRoo]

Hi All,

I'm in the process of bleeding the brakes after installing stainless lines and of course the lever stayed nice and spongy. I followed people's advice to try and get the master cylinder higher than the banjo bolt. I'm not a great fabricator by any stretch of the imagination, unlike some of you on the forum,but I'm pretty pleased with the little jig I cobbled together. It tilts the master cylinder enough to lift it higher than the banjo.



Gently squeezed the lever and sure enough: more air coming up!:) I have built up pressure and tied the lever back with a cable tie to let it sit overnight and get rid of any remaining air.

Using a syringe to add the brake fluid from the bottom definitely works because there was hardly any air coming out of the calipers when I bled them. If everything goes according to plan the brakes should be right to go tomorrow.

Cheers,

Mike

[Finnpaso]

You did just right way it, but i would still turn that master cylinder more "upwards", as u can imagine, that if air is in banjo bolt, then it have to turn "enough" that air really feeds from banjo to master cylinder... When air feeds to master, then next day only with very sensitive fingers pump many times lever and all air feeds to master cylinder liquid cup. If You carefully open that cover and start pump then U can see air bubbles coming out from piston to liquid cup, but have to be very carefull when do that and open cup, as liquid is very harmfull to paintings... Good job! It only need accurate job and right directions, nothing else and i cant anymore imagine that i would try feed new liquids from up to down, as then possible air bubbles go up and down and up and down in lines without coming out....That banjo bolt is very critical point for air !

[Mustang505]

So Mike - did it work? I have just bought a cylinder seal kit from Gowanloch as my brakes are spongy as hell. did not know this trick with the bango bolt.

[ducapaso]

Still thinking that the best is bleeding ALSO from banjo bolt.
Never miss protecting paints with wet canvas!
water saves pant from being corroded by dot 4 oil

[Finnpaso]

Bleeding from banjo is another method, but then its better to buy "bleeding banjobolt" and then its very easy also that way.... I know there are such in markets. surely! Anyway if open those banjo bolts then they washers have to change sometimes, as normally there are washers from copper and more make pressure(tighten them), then they go harder and harder, and then they start to leak easily, so its not so bad idea to change copper washers every time open banjo's

[Mustang505]

Hi Guys
tell me if this is normal - when pulling the brake lever without the reservoir cap on, you can see a jet of fluid shoots up out of one of the small holes in the bottom of the resesvoir. If you pull the lever hard it's strong enough to shoot out and spill all over the place. I have never seen this with any other brake system i have worked on so hence my question - is that the same on your bikes or is there something wrong in my master cylinder?

[ducapaso]

It's working fine.
Putting the pump almost vertical will be helpful in bleeding the banjo bolt.
Fill the reservoir tank and put the cap, but remember to wash carefully any painted part as soon as oil spots it

[Finnpaso]

Mustang505, its just normal what You noticed. It function just that way But DONT pull lever fastly when cup is open, as then liquid flyes to fairings easily and damage paintings! Nicola say it right way. You dont have anything "wrong" in Your master cylinder....

[Mustang505]

Cheers guys, thanks for your help.

[macchiman]

I also think it helps to hold the master cylinder in such a way as the 2 holes in the actual cylinder bore are at the top, the air you're trying to get out of the fluid (from the banjo bolt, etc) has to go somewhere and that's where it will escape. I tend to put the new fluid in the cylinder, put the lid back on, then pump slowly, stops fluid getting everywhere.

Martin Philp
Paso 750

[Mustang505]

Just some info that might be helpful for anyone else heading down the route of fitting new master cylinder kits.
I bought a 13mm kit for the front brake (PS13) only to find when it arrived that it was too small when restripping the master cylinder - mine is a 15mm. So have ordered PS15 from Bevel H.
Now not sure if my Sport has had an upgrade 15mm fitted or if the Sport is 15mm standard. I read somewhere on this forum that the Paso is a 13mm front brake?? Maybe not, maybe also a 15mm?? The instructions with the PS13 kits keeps talking about rear brake. I'm going to keep the PS13 in case it fits the clutch or rear brake. But my guess is the rear is a 12mm cylinder?

[Mc tool]

Is there not a number on the cyl

[PasoRoo]

Hi Clive,

Sorry for the late reply but I have been away for the last week. The brake is a lot better but still not as firm as I expected. I think there may still be some air in the lines or the banjo. As Antti mentioned in an earlier post it is a bit of a patience game. Tilting the master cylinder helped a lot and brought out some more air bubbles so it is definitely of benefit.

I am a bit hesitant to 'crack' the banjo bolt at the master cylinder because it has copper washers. If they don't seal properly after loosening the banjo I would have to take it off and be back at square one.

I top up the master with brake fluid and then put the cover on before squeezeing the lever. The first time I tried to bleed the brakes I had the same experience as you and squirted brake fluid everywhere! Lots of water to rinse off the fluid prevented any damage to the paint.

As far as I can tell the master on my Paso is the original and it is a 15mm.

Cheers,

Mike

[jcslocum]

I have a big vacuum bleeder and this is the way to really get all of the air out. You canmake one with a coffee can and then use you shop vac to provide the vacuum source. All you need is a helper to keep the reservior full as you draw the fluid down/ The good thing about this kind of vacuum, is that it is a constant flow and does not allow the air to float back up the tube.

[Finnpaso]

Jon, such is best way for change brake/clutch fluids, but everyone is not ready to invest to such vacuum system. Indeed also i am not ready, as i have managed with "normal systems" every time, but have to know some "tricks" how to do it..