Kiwiz, I have bleed brakes many times before and occasionally have seen some fountains of brake fluid!
This has happened on a couple of bikes, not every time, and the brakes always ended up working OK.
Don't really know why it happens tho? The spray is only an inch or so tho! :p
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Spongy front brake - Can each component be tested?
Moderators: KeithZ1R, chrisu, paul doran, Taffus
as the pistons pushes forward the fluid will escape through the bleed hole until the seal cuts the hole off, after all you do have to have some way for the fluid to get into the chamber. This is quite normal. Check the RH hole also is clear, it's usually a very fine hole through, and check that you don't have air trapped in the system, banjos, pressure switch and m/c especially.
This was a 10% useful information production!
This was a 10% useful information production!
Rich
diplomacy is a form of art - I was never any good at art
diplomacy is a form of art - I was never any good at art
Kiwiz,
If you have an old lever, try drilling and screwing a small pan head screw into the lever where it contacts the M/C piston. you don't want the head of the screw any more than about 2mm thick.
I have used this twice before, and am currently using it on my 900A4. The explanation giving to me, (By a race engineer shop) was that an old, but good surfaced, bore can develop a slight taper in it. The screw will push the piston slightly further in and makes a world of difference to the feel.
If you have an old lever, try drilling and screwing a small pan head screw into the lever where it contacts the M/C piston. you don't want the head of the screw any more than about 2mm thick.
I have used this twice before, and am currently using it on my 900A4. The explanation giving to me, (By a race engineer shop) was that an old, but good surfaced, bore can develop a slight taper in it. The screw will push the piston slightly further in and makes a world of difference to the feel.
Begging your pardon sir, but you did say that you'd like .................a green one?
Sorf, not at all sure the problem is the MC given the test I undertook by blank off the outlet with a bolt and applying lever pressure. The thing was rock solid.
Took the LH caliper off (the only one that hasnt had a new seal kit and piston) and it looks like the slave assembly has been leaking as a lot of paint has been eaten away from the lowest point of the caliper and there was a lot of moist crud in the dust seal groove which is outside of the fluid seal groove. This piston itself has about half a dozen small rusty pits its its polished steel surface.
Looks like a new piston and seal kit is required. Anyone know how available these are, particularily the piston? If one has to be made what is the ideal material; Stainless?
Took the LH caliper off (the only one that hasnt had a new seal kit and piston) and it looks like the slave assembly has been leaking as a lot of paint has been eaten away from the lowest point of the caliper and there was a lot of moist crud in the dust seal groove which is outside of the fluid seal groove. This piston itself has about half a dozen small rusty pits its its polished steel surface.
Looks like a new piston and seal kit is required. Anyone know how available these are, particularily the piston? If one has to be made what is the ideal material; Stainless?
Success is the ability to go from one failure to another without loss of enthusiasm
Kiwiz, I just purchased an aftermarket piston, not necessarily made for my Z1 series caliper. So, I imagine you would also be able to get a replacement. All that was needed was to give them (The brake repair company) the sizes and they look up a "catteldog" and you have it.
The equivalent piston for the Z1 series was from PROTEX. The numbers on box were 090P0180..... A11R2H. The brake company was Warringah Brakes at Brookvale, Sydney. The sizes were correct, except it was slightly (3 mm) shorter in length. The rubber dust cover fitted and it worked! Aus$25.
I would still suspect air in your system if it is still spongy, probably caliper or splitter... where else is left?
As I have found out only recently..... there should be a squirt of fluid thru the LHS hole!
RegardZ
The equivalent piston for the Z1 series was from PROTEX. The numbers on box were 090P0180..... A11R2H. The brake company was Warringah Brakes at Brookvale, Sydney. The sizes were correct, except it was slightly (3 mm) shorter in length. The rubber dust cover fitted and it worked! Aus$25.
I would still suspect air in your system if it is still spongy, probably caliper or splitter... where else is left?
As I have found out only recently..... there should be a squirt of fluid thru the LHS hole!
RegardZ
Garn (Sydney) Z1, Z1A, Z1B and Z900-A4
garn 1,
thanks for your ideas on sourcing the pistons from other than friendly kawa dealers. The last piston was replaced while the beast was in Sydney, but from I think some dealer in Homebush.
The brake shop I am dealing with are pretty efficent, having done work in resleeving and making a one off piston for an old Norton Commando MC as well as making up the stainless hoses. So I will mention that idea to them as see what they can come up with.
thanks for your ideas on sourcing the pistons from other than friendly kawa dealers. The last piston was replaced while the beast was in Sydney, but from I think some dealer in Homebush.
The brake shop I am dealing with are pretty efficent, having done work in resleeving and making a one off piston for an old Norton Commando MC as well as making up the stainless hoses. So I will mention that idea to them as see what they can come up with.
Success is the ability to go from one failure to another without loss of enthusiasm
Rich,
thanks for the ebay lead I am now up one piston which it looks as though I might need.
Took the bike to the brake shop where they smiled smugly that "some of the bikes are difficult to bleed". 6 hours later they called to say the problem wasn't air in the system but they were now sure it was some caliper problem which they have dismounted for bench testing.
The caliper seems a fairly simple device so I am really curious what can go wrong with it. The piston is slightly pitted around where the seal rubs , but these are no more that tiny pin pricks in size. Whilst there seems to be some evidence of fluid leakage in the caliper (paint eroded from underside, moist crud in the dust seal groove), applying pressure to it doesn't seem to provoke a lot of fluid escape.
One point someone could perhaps comment on is that this caliper is of the one piston sliding type. The lower of the two caliper sliding pins is waisted and has a plastic sleeve one of which is so munted I removed it. I assume this is just some anti rattle system and not critical to the braking system?
Anyway they are continuing the investigation but sounds like new seals and pistons will be a must. After that there isn't much left!
thanks for the ebay lead I am now up one piston which it looks as though I might need.
Took the bike to the brake shop where they smiled smugly that "some of the bikes are difficult to bleed". 6 hours later they called to say the problem wasn't air in the system but they were now sure it was some caliper problem which they have dismounted for bench testing.
The caliper seems a fairly simple device so I am really curious what can go wrong with it. The piston is slightly pitted around where the seal rubs , but these are no more that tiny pin pricks in size. Whilst there seems to be some evidence of fluid leakage in the caliper (paint eroded from underside, moist crud in the dust seal groove), applying pressure to it doesn't seem to provoke a lot of fluid escape.
One point someone could perhaps comment on is that this caliper is of the one piston sliding type. The lower of the two caliper sliding pins is waisted and has a plastic sleeve one of which is so munted I removed it. I assume this is just some anti rattle system and not critical to the braking system?
Anyway they are continuing the investigation but sounds like new seals and pistons will be a must. After that there isn't much left!
Success is the ability to go from one failure to another without loss of enthusiasm
"The piston is slightly pitted around where the seal rubs , but these are no more that tiny pin pricks in size."
Which will destroy the seal as they go in and out making the caliper leak as per below.
"Whilst there seems to be some evidence of fluid leakage in the caliper (paint eroded from underside, moist crud in the dust seal groove), applying pressure to it doesn't seem to provoke a lot of fluid escape."
Unfortunately applying pressure should provoke ANY fluid escape, the seal groove may also need to be cleaned out (the alloy oxidises behind the seal forcing greater pressure on the piston leading to it not retracting properly) when you do the new seals. Where fluid escapes from air will probably get in to!
Don't know about the bolts as I haven't taken z brakes to bits and haven't had anything without opposing pistons for ...... years!
Which will destroy the seal as they go in and out making the caliper leak as per below.
"Whilst there seems to be some evidence of fluid leakage in the caliper (paint eroded from underside, moist crud in the dust seal groove), applying pressure to it doesn't seem to provoke a lot of fluid escape."
Unfortunately applying pressure should provoke ANY fluid escape, the seal groove may also need to be cleaned out (the alloy oxidises behind the seal forcing greater pressure on the piston leading to it not retracting properly) when you do the new seals. Where fluid escapes from air will probably get in to!
Don't know about the bolts as I haven't taken z brakes to bits and haven't had anything without opposing pistons for ...... years!
Rich
diplomacy is a form of art - I was never any good at art
diplomacy is a form of art - I was never any good at art
-
z1apaul
ive just finished a z1a rebuild with new z-power lines right thro new pads and mc repair kit and thats real spongey too. i did make the small hole bigger in the mc though cause i thought it was blocked,its still less than the other one, have i ruined the mc?the brake works but comes nearly to the bars do i just keep bleeding it the piston sticks sometimes aswell will this get better if i keep pumping it in the garage i didnt lube the piston on assembly, paul
Paul.
the brake shop told me it was binding in the pins along which the single piston calipers slide. I remain to be convinced! I am about to embark post (new year) on a rebuild of the calipers: new seals and pistons. At that point every hydraulic braking component will have been replaced We will see
the brake shop told me it was binding in the pins along which the single piston calipers slide. I remain to be convinced! I am about to embark post (new year) on a rebuild of the calipers: new seals and pistons. At that point every hydraulic braking component will have been replaced We will see
Success is the ability to go from one failure to another without loss of enthusiasm
Kiwi,
I am sure you will have thought about this, but you are not using silicone brake fluid are you. Its supposed to be non hygroscopic ie does not absorb water and it does not strip paint like normal brake fluid BUt its more compressible apparently and when I tried it on my old z1 a few years ago it made the brakes horrible and spongy. Just thought i would mention it on the off chance.
good luck.
I am sure you will have thought about this, but you are not using silicone brake fluid are you. Its supposed to be non hygroscopic ie does not absorb water and it does not strip paint like normal brake fluid BUt its more compressible apparently and when I tried it on my old z1 a few years ago it made the brakes horrible and spongy. Just thought i would mention it on the off chance.
good luck.
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