HELP ! Very little hair left...(Brakes)

[G JONES]

We have been trying for a while now to give our 350 an airing - entered Tonfanau in July - and failed to get there - new brake lines didn't turn up in time - looks like we will miss Tomorrow now as well...(Sorry to craig hauxwell - who had arranged a passenger)
Now looking for some advice regarding brakes....am now really at the end of my tether (or rope if I can't get this sorted)
I had an all night session with it on Fri night - which I wouldn't mind if I was making progress....- so here's the story.
Shelbourne 350 (ex John Brindley 1992 ish) has been laid up for 12 years.
So before I run it again - I decide it is sensible to do (among other things) the following:
Replace seals in Calipers:
(AP RACING CP2696)
http://www.apracing.com/info/products.a ... _2536_1085" onclick="window.open(this.href);return false;
Replace seals in Master Cylinders:
(AP RACING CP2623)
http://www.apracing.com/info/products.a ... _2386_2385" onclick="window.open(this.href);return false;
Replace all brake lines.
I also invested in an ultrasonic cleaning tank - because I had read that they were good for cleaning delicate parts - and would be good to clean the insides of all the parts.
I thought I had it all covered - but no...
The brakes are set up as:
M/cyl # 1:
Single long hose to Front Left caliper - link hose to Front right caliper.
M/cyl # 2:
Single hoses to sidecar / rear wheel.
The S/car / Rear brake bled with about 6 - 10 strokes - no trouble at all..
The front pair - well after an almost all night session - and most of today - I have put about 2.5litres through the system - and still no usable brake.
Sorry for the length of post - but I thought it better to try and explain the situation as well as possible - I can only now imagine that there is a blockage - or corrosion somewhere that I have missed - has anyone any experience of refurbishing brakes after a long period out of service ?
I am now wondering if I should have just sold it on years ago - and bought a fresh outfit now - but then it's always easy with hindsight...
(Note to Steve - no fee if you are still in need - or did you fall out with me ? )

[bill]

did you remove the callipers to get the bleed nipples at the highest point while bleeding them?

it does make a difference, did mine this year and no problems

[G JONES]

did you remove the callipers to get the bleed nipples at the highest point while bleeding them?
it does make a difference, did mine this year and no problems

Hi bill - thanks for that - yes I had them in every conceivable position I could think of - on the bike - and off - just sat looking at them on several occasions before I resorted to the really big hammer - tried the pressure bleed - which has worked a treat in the past - but still no joy - that's why I am now wondering if there is something wrong with the M/cyl or caliper....only was hoping not to have to buy new stuff just to find out....athough - I would have done that if I knew which part was causing the problem.
I did think that corrosion / muck might be a problem - hence the ultrasonic - whether it did any good - who knows - anyone with any experience of them ?
I really can't see why these brakes should be such a ba*tard to bleed - It's hardly rocket science - just a few bits of metal with a hose connecting them - or is there more to this than meets the eye ?
Never had any bother bleeding brakes and clutches on anything else in the past...(far as I can remember)

[bill]

hi,

did you split the two halves of the callipers when you rebuilt them? the hole between the two halves is tiny and could have been blocked.

seem to remember the hole between the two halves being in a bit of a strange position

will strip a caliper tomorrow and have a look

will pm you my number, give me a ring tomorrow and i will try to sort it out, i could bring a couple of my calipers down, which i know are ok, for you to try so you can elimenate that side if the system

[G JONES]

hi,
did you split the two halves of the callipers when you rebuilt them? the hole between the two halves is tiny and could have been blocked.

Hi - no - have to admit that I did not strip the two halves - I had thought they were better left undisturbed - but I now have to be thinking that was a big mistake.

will pm you my number, give me a ring tomorrow and i will try to sort it out, i could bring a couple of my calipers down, which i know are ok, for you to try so you can elimenate that side if the system

Much appreciate the offer - please don't strip a caliper you have fitted to the bike ! - you might not be able to bleed it again !
I you have a "dry" one - ok....
I'm at the point now where I don't want to look at brakes for a day or two - but that may change when I get some kip - I'm packing up now - totally knac*ered...

[G JONES]

Still trying to work out what's happening with this setup...
I found a technical sheet for the CP2623 - which specifies

no more than 4 degrees angularity

for the pushrod relative to the bore of the cylinder.
The way the brakes work means that once you have a "bled" m/cyl on the one circuit - the pushrod only moves a short distance until it comes under pressure - the actuator will then keep moving on the "unbled" circuit - and push the pushrod over at an angle to the bore.
I'm now wondering if that angle is enough to cause an air leak when bleeding.
The way the brake pedal / arm etc is setup - is just how it was when I got the bike (other than swapping girling for AP m/cyls)
I have always had problems getting these brakes bled - that's why I went to pressure bleeding - didn't work this time though.
All this is guessing at the moment - and clutching at straws - I will need to think up some way of actuating the second m/cyl separately before I can test it.
Anyone with some experience of these cyls (and the "angularity" thing) - could they really draw air ?
Are there any pedal / cyl layouts that are able to control the pushrod - and keep it parallel to the bore ?

[mrequipe]

I had that set up on my shelbourne, 2 problems the first being not enough leverage couldnt stop the thing second no bias control. Your system is pushing towards the cylinder with the double banjos on. I cut it all off and did something different. I use a balance bar with a rod attached to it that goes in between the centre of the master cylinders and through a bush so it always pushes straight, then you get proper bias control on the balance bar. I link my brakes 2 front together side and rear together for bias purposes then when its wet you can wind it off the front brakes. Some people prefer it the other way.
Even if they are at a bit of an angle they shouldnt leak, they have a ball on the end of the pushrod which allows for a lot of misalignment

[bill]

you could try swapping the brake hoses for the front brakes onto the master cylinder for the rear, this might help to see if it is a fault on master cylinder or not

as Mike says, the master cylinder should not draw air even if the push rod is out of line

[G JONES]

I had that set up on my shelbourne, 2 problems the first being not enough leverage couldnt stop the thing

Hi mike - take your point - not too bad after I changed the Girlings for AP - but always room for improvement...

second no bias control.

Yes - I've been looking for something to rectify that - or the components to make something up - no real joy yet....

I use a balance bar with a rod attached to it that goes in between the centre of the master cylinders and through a bush so it always pushes straight, then you get proper bias control on the balance bar.

difficult to visualise - even though your explanation is excellent - any pictures ?

I link my brakes 2 front together side and rear together for bias purposes then when its wet you can wind it off the front brakes.

I've always had mine set up the same - but unfortunately no facility to adjust the bias...

Even if they are at a bit of an angle they shouldnt leak, they have a ball on the end of the pushrod which allows for a lot of misalignment

I guess I was clutching at straws there - after reading the 4 degrees limit on the AP tech sheet - I thought I might have a possible reason for all the problems - It would still be good to try and set up a way in which to bleed the m/cyls separately though...

you could try swapping the brake hoses for the front brakes onto the master cylinder for the rear, this might help to see if it is a fault on master cylinder or not
as Mike says, the master cylinder should not draw air even if the push rod is out of line

Thanks bill - I will probably do a swap on the lines / cyls - need to get some more fluid before I can continue the battle though (I've used a hell of a lot up to now - not funny ) - unless I succumb to the ultimate evil of re-using the fluid for test purposes - and refilling with fresh when I start to see some progress...

[mrequipe]

You can get a balance bar from demon tweeks for about £40 which will go straight on to your cylinders, but you will have to weld the tube bit to your pedal (bit of modification).
PM your address gordon and I will send you a sketch

[mrequipe]

Just thought of something else, I usually pressure bleed them then finished by hand, but a couple of times when ive been having trouble I have filled a push bike pump full of fluid put the rubber end on (after cutting off the valve end) open the bleed nipple and forced it through that way and its worked every time, do it on all calipers

[G JONES]

You can get a balance bar from demon tweeks for about £40 which will go straight on to your cylinders, but you will have to weld the tube bit to your pedal (bit of modification).
PM your address gordon and I will send you a sketch

For anyone else looking for these - there is also a Tilton one there...
http://www.demon-tweeks.co.uk/products/ ... R/PBAL/BAR" onclick="window.open(this.href);return false;
I will order one right away - I've not had chance to pull one apart - but I imagine the centre tube bit is able to slide side to side - to allow for the arc of the pedal ? - or am I looking at it all wrong (wouldn't be the first time )

Just thought of something else, I usually pressure bleed them then finished by hand, but a couple of times when ive been having trouble I have filled a push bike pump full of fluid put the rubber end on (after cutting off the valve end) open the bleed nipple and forced it through that way and its worked every time, do it on all calipers

"push bike pump" - you got all the best "stuff"
Sorry for that mike - couldn't resist that...
It's a case of "needs must" sometimes - I was also thinking of getting one of the mityvac vacuum pumps - just wondered if anyone has any experience with them ? - although some of the guys at mitsui used to swear by them - and that's over 25 years ago...

[steve-e]

mityvac is good.

[G JONES]

mityvac is good.

Thanks steve - pretty emphatic about that....

[steve-e]

I was typing on my phone in the pub

Mityvac are excellent.

There you go, longer answer. Brilliant on my XV16