Master cylinder disassembly

[keithtraffic]

Many thanks for the comments.

I have seen the note about silicone grease in the Honda manual so have purchased some of that and (perhaps luckily) I had already thought to replace the piston seal so have a brand new one.

It is still quite remarkable that its only this that brings the piston back to move the brake pad away from the disc!

[K2-K6]

It is still quite remarkable that its only this that brings the piston back to move the brake pad away from the disc!

Agree,  it's just such a simple elegant solution that could have had any number of complex ideas applied to it. I'd be pleased if I invented that one   

On the same basis,  I use some thick wall small bore rubber tubing (bought from local car parts shop) that fits tightly onto the bleed nipple,  push a bolt in the other end to seal it, then with a scalpel cut a 10 mm long slit just up from the bolt. 
You can now open the bleed valve a 1/4 turn and just pump the fluid through as it's a particularly effective one way valve.

I use this on cars too to bleed through systems without anyone at the caliper,  just buy a piece long enough to reach down to a container on the floor.

[Moorey]

You used to be able to buy bleed pipe just like that, it was usually orange in colour and was just a rubber pipe with a slit in it near the end.

You still can and they work very well.
https://www.ebay.co.uk/itm/BRAKE-CLUTCH-BLEEDING-TUBE-PIPE-WITH-METAL-STOPPER-ONE-WAY/254342217928?epid=1130461392&hash=item3b37fa40c8:g:pNQAAOSws29bxgdw

[K2-K6]

I've always made mine longer at about 1 metre so you don't have to balance the jam jar on top of a couple of treacle tins to reach calipers on cars. 

[matthewmosse]

Those orange brake bleed pipes are rather effective, well worth having. I found a gibsons Eazi bleed kit dead handh on the car what with Abs pumps and convoluted routing but on a bike the orange tube 8s rather effective, other handy trick it that fails is get a drenching syringe with 6mm end, bit of pipe that goes from bleed nipple to the syringe, this can either suck fluid through from the caliper end or on occasion I find a stubborn master cylinder and nothings getting fluid through and pushing brake fluid through from the caliper end ( taking care not to overflow the reservoir)  has got things working again.

[Piki]

I use this Drapper Brake Bleedind Kit, Works perfect for me...…

[Piki]

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[keithtraffic]

So, I have now completed the brake re-build. Actually bleeding the brakes was not the drama I was expecting and after a few false starts to get the fluid flowing I seem to have been able to get all the air out and the brake seems good and firm when applied, with about the right amount of brake lever play. I will leave it until tomorrow and re-check to see if any more air come out but I am not really expecting any.

Because of the brake binding issues which started this all off, I have very carefully rebuilt the whole caliper bracket and hinge pivot assembly, which now seems much better and swings nice freely before I fitted the callipers. I have adjusted very carefully the caliper adjusting bolt so the fixed pad just drags slightly, then backed it off half a turn (as detailed in the workshop manual), so the wheel spins freely.

However I note that when I apply the brake and then release it there is still a little bit of drag on the wheel - its nothing like what was previously experienced, where the brakes really seemed to bind, but it is still there. Is this normal, particularly with new brake pads or is something still not quite right.

[K2-K6]

There's an imperfect geometry in play that affects alignment generally with new pads.  The rear support for the pads ( back face away from friction material)  "should " accommodate this but may not fully rectify.

The caliper would ideally have it's pads travelling at 90 degree to disc,  but they swing on the arm in that radius.  With new "flat" pads it can take a little bedding in before they sit perfectly to the disc face at which point the technical error is effectively built in to the pad geometry.

It may take 30 miles or so to achieve the above,  then recheck your setup to fine tune.  Assess from there.

[Trigger]

If the brake pads have paint on the outside edge, remove it. The pad should not be tight in the caliper. Also check that you have the correct gap on the rear pad to disc, this can move when you tighten up the lock nut so, always check again 

[keithtraffic]

Thanks - have just taken the bike out for a test ride and the brakes seem to be fine - just a little 'squeaky' but maybe that's to be expected from new pads. As suggested I will do a few more miles then recheck the setup as I did notice, even when setting up the first time, that I had to re-adjust slightly as tightening up the lock nut did move things.

Interesting before I re-worked the whole assembly I did notice a distinct 'knocking or clanking sound sometimes from the front brake assembly when I went over significant bumps - but this has now gone away which I take to be a good sign!