Bust when you've spent 48 hours trying to bleed the rear brake. I treated the SS to a set of Woodcraft rear sets. Got them fitted and the niggles sorted fitted the rear master cylinder with the new lines bled through and we're up and running. However a few days later I noticed a leak comming from the remote connection, so I though I'd throw on a spare, no joy, couldn't get it to work. As its history was unknown I got a new master from Deamon Tweeks and fitted it up this weekend, and then spent the entire weekend trying to get a working brake. So I'm using a big syringe on the bleed nipple to pull the fluid through with the brake leaver down as far as it will go still with no effect. I've pre filled the lines, had the caliper above the remote res. All I appear to have pulled through is the fluid in the caliper and the line. I've even filled the syringe with fuild in attempt to reverse bleed the system and I can't push the fuild back through. It's almost like the fluid can't get past the piston in the MC which was the effect I was seeing with the spare. I 've even wound the push rod out to make sure the piston is moving all the way. I can put the old MC on and have it working in 10 mins. I can't belive a new MC is faulty and I can't believe I'm making as bigger hash of this as I appear to be. So if anyone can see where I'm going wrong I'd be very grateful. Thanks Martin
remove rear caliper and hold it above the master cylinder as high as poss, remove bleed screw and leave it for a while so the air can escape. Find something which is the same thickness as the disc, or use the disc and with the calper still above the master cyl and fitted on loose disc bleed it. Would be less hassle with help. Hope this helps it works for me.
I am not sure if I am understanding it correctly. However +1 with Imola. You also mentioned having the lever pushed down, if I have it right then you won't be able to bleed to the reservoir as the line will be blocked at the M/C piston. If you have the lever in the normal "not activated" position then you should be able to positive bleed, reverse bleed etc: I sometimes find I need to do a combination of bleed techniques to get rid of all the air sometimes. John
Alternatively, drop the caliper onto the floor, push the pistons right back and jam them there with whatever (I use a thick spanner); fill the MC reservoir; press the pedal very slowly and release slowly a few times (watch the air rise into the MC reservoir), then wait an hour (drop the cap onto the MC while you wait). Or, while it is on the floor, use the syringe to fill from the bleed nipple (need a fairly big syringe though)...... ....I also have to bleed from the hose to MC union sometimes. AL.
You can also tie or wedge the brake pedal down and leave overnight, raising the caliper so that bleed nipple is uppermost , then release bleed nipple in the morning
Thanks for all the replies chaps. I did have a pretty big air lock in the pipe to the reservoir. I'll set this up over night as see what happens.
The Imola Technique So here we are with the Imola bleed technique I had a quick look down the hole where the bleed nipple sits and its totaly dry. I'll leave this for 24 hrs an see what occurs.
That looks good. Only thing I'd have done different would have been to have the bleed nipple at the highest point if feasible John
Hi John, The hoe for the bleed nipple is behind the banjo bolt, but I see what you mean though the far end of the caliper is slightly higher. We will see what transpires tomorrow.
Well chaps we have a winner, well almost. After 48 hours number one son informed me he had used up most of the fluid in the reservoir and had now managed to get the pads jamed together Anyway after fiddling around for an hour last night I now have a working brake, however I'm not happy with the biting point as the lever travel seems a bit excessive and I can't seem to firm it up. Does anyone have any advice on how I can improve this?
Can't think of anything to shorten lever travel, maybe mess with the pedal adjustment, which is obvious. I think to actually shorten the lever travel you are into playing with M/C to S/C ratios and that can get expensive and hit an miss. That's my knowledge on the subject exhausted John
Thanks John, thats pretty well my knowledge used up as well. The only thing I know thats different about this new M/C is that is a 13mm and the original was 11mm I think. If I'm wrong then I'm sure someone will correct me. Martin
I had exactly the same thing with my SS OEM rear brake set-up......I had to do a small bleed where the hose connects to the MC first...... Is it excess travel or excess free play before the lever rod starts touching the MC? I had to reduce the free-play to almost zilch. AL.
HI Al, Its excess free travel. I've wound the adjuster in untill the the pads just touch the disk then backed off a quater of a turn, but it still not as good as the original. It only moved about 10 deg and the brake was on. Mind you that might explain why the rear disc needed changing every 3 years or so with excess run out.
Sorry Martin, that doesn't make sense to my tiny and aged brain.......but I seriously hope you haven't adjusted the rod to 'preload' the MC, otherwise you are asking for trubble........ Grandma's eggs an' all that, but the rod with the nut should be adjusted so that there is no contact between the road and the MC piston until the brake lever has been pushed down a bit..... ....if you can't hear it make contact you should be at least be able to feel it.......I used to have about 10mm of pedal travel (at the toe end) before the rod touched, it is now down to 3mm....which is a nuisance for me because my foot hovers over the brake pedal when riding. It used to touch slightly until I realised it was moving the pads onto the discs a bit...so I had to alter the pedal angle down slightly to keep my foot off it until needed. AL.
I could have this arse for tit Martin, but my recollection is that if the Master Cylinder bore diameter rises then you should end up with a shorter travel and a harder push at the lever. If you think about it your just moving "X" volume of fluid to push the pads onto the disc. If you have a larger M/C then you are going to push a larger volume with a shorter movement. If you need to push the lever further than the old smaller diameter cylinder maybe (your not goanna want to hear this) maybe it needs bled some more. My calculations may be out but going from 11 to 13 diameter will increase M/C area by nearly 40% so if my theory is right then you should definitely be feeling a shorter harder push. John
Al your right about the preload issue, I went and double checked last night and the pads were still touching, so I've wound the rod right back. So I'm now going to have a nother go at re-bleeding the brakes.
No John you are correct about the increase in volume over the old. I've already come to the conclusion I'm going to have to do some further bleeding. Thnaks for correcting this tired old brain thou.
