Scooterotica

Hi, I'm having hours of grief trying to bleed an Outboard Disc brake. Does anyone have any suggestions on the best way to do this? I have even tried back filling the system through the bleed screw with a syringe ( this as worked in the past), but failed. The first outboard RS type disc brake I purchased about 4 years ago sort of self primed its self just by operating the master cylinder piston in and out and releasing and tightening the bleed screw, the last one was a pig and required the syringe and this one is an utter Bas****. Help!

I have a tube with a non-return valve inside it, its a great bit of kit which i picked up a long time ago so not sure if you can still pick them up...basically its like a petrol pipe with a non return gismo in it that stops the flow of brake fluid at source and does not allow air to penetrate into the pipe past the valve...used this on all sort of brakes from cars to twin disc bikes and its always worked first time and given a solid brake...

Had a look at buying one, Halfords sell them, they@re called "easyibleed", but would not work on the RS bleed screw as the thread is parallel and very baggy when slackened off a turn, so would leak air/oil down the side of the threads.

Thanks for that Lam46. The trouble though seems to be the master cylinder, or more to the point, getting it to pump. If you put oil in the reservoir and operate the piston , nothing comes out of the outlet port, but if you fill the outlet port with oil, put your finger over and pump, I get instant pressure. So basically its how to get everything primed back to the outlet port.

hydra wrote:Thanks for that Lam46. The trouble though seems to be the master cylinder, or more to the point, getting it to pump. If you put oil in the reservoir and operate the piston , nothing comes out of the outlet port, but if you fill the outlet port with oil, put your finger over and pump, I get instant pressure. So basically its how to get everything primed back to the outlet port.

Is it just easy to make it a 2 person operation ?..I to be honest have never had a problem with this on all sort of vehicles!...Is the nissen system awkward to bleed ? never bled one of these!

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Is it just easy to make it a 2 person operation ?..I to be honest have never had a problem with this on all sort of vehicles!...Is the nissen system awkward to bleed ? never bled one of these![/quote]

The people I have spoke to say, some are ok, others can be stubborn.

remember to keep the lever pulled in while you tighten the bleed screw

My RS brake was a real pain. I tried the usual way, open the nipple pump lever close nipple release lever... no good. Then I tried reverse filling through the nipple... no good. As a last resort I had to slighty open the nipple topped up resovior and let it gravity fill for a couple of day, it took 3 days before I got slighty presure at the lever so I could bleed it normally. Hope this helps

Just an idea but happened to me , check the banjo bolts as i once spent days trying to fill a rear disc i had fluid in master cylinder and fluid at the bleed nipple but the brake wouldn't work in the ended i stripped it down and found the banjo bolt had abit of plastic from the pipe trapped in it and it was working like a non return valve letting fluid through but not letting air bleed out !

Thanks everybody for your help, sorted it today though, ended up changing the master cylinder Piston. The old RS master cylinder Piston has like a worm gear scroll between the two seals whereas the new is straight. don't know what difference this makes but with the older type piston with each pump of the lever, air came out of the two holes in the reservoir and eventually self bled even without the bleed screw in about 15 mins.