My great circlip hunt...
Discussion
Hi Guys & Gals,
About 6 months ago my Yamaha Majesty 180 scooter rear brake stopped working when applied.
The pads & calliper move freely when the lever is pumped but no braking effort is achieved against the disc.
The disc thickness is well above minimum limits and not warped or grooved as are both pads.
The master cylinder is a Brembo PS12 unit with matching calliper at the back.
I tried standard bleeding and reverse bleeding - made no difference.
On visual inspection there was nothing out of the ordinary happening in the m/c when pulling the lever.
I stripped and inspected the calliper and everything looked fine.
The hose also looked fine along its length on inspection.
I then stripped the m/c and on removing the piston retaining circlip, it snapped.
All the m/c components looked fine, so this is still a bit puzzling.
It is a 16mm internal circlip with extra abutments - which I understand is a DIN984 JK16 or K-type - aka a D2000.
Getting a couple of replacements is proving impossible.
Yamaha don't supply them or m/c rebuild kits. They suggest buying a whole new m/c assembly - there's a surprise!
Brembo don't supply them or a rebuild kit for the PS12 m/c. As above, buy a new m/c!
Aftermarket m/c rebuild kit manufacturers/suppliers insist they can't cross-reference if any of their kits will fit the PS12 m/c.
Brake rebuilders also state they can't help.
Fixing/component suppliers state they don't supply the DIN984 type.
I did find out that the Honda CB500 brake m/c uses the same circlip and it was available separately with its own part number! (90651-MAK-003)
However, all Honda parts suppliers are coming back that it is no longer available/discontinued by manufacturer & nobody has any stock.
I found some Chinese manufacturers who can supply these but their minimum order is 5-10 thousand!!! With no negotiation as it is not a stock item and would be manufactured on acceptance of the order.
So, anyone on here know where I might be able to get 2-3 of these 16mm internal circlips with extra abutments? (pic below)
Would be much appreciated
Thanks,
Mark
About 6 months ago my Yamaha Majesty 180 scooter rear brake stopped working when applied.
The pads & calliper move freely when the lever is pumped but no braking effort is achieved against the disc.
The disc thickness is well above minimum limits and not warped or grooved as are both pads.
The master cylinder is a Brembo PS12 unit with matching calliper at the back.
I tried standard bleeding and reverse bleeding - made no difference.
On visual inspection there was nothing out of the ordinary happening in the m/c when pulling the lever.
I stripped and inspected the calliper and everything looked fine.
The hose also looked fine along its length on inspection.
I then stripped the m/c and on removing the piston retaining circlip, it snapped.
All the m/c components looked fine, so this is still a bit puzzling.
It is a 16mm internal circlip with extra abutments - which I understand is a DIN984 JK16 or K-type - aka a D2000.
Getting a couple of replacements is proving impossible.
Yamaha don't supply them or m/c rebuild kits. They suggest buying a whole new m/c assembly - there's a surprise!
Brembo don't supply them or a rebuild kit for the PS12 m/c. As above, buy a new m/c!
Aftermarket m/c rebuild kit manufacturers/suppliers insist they can't cross-reference if any of their kits will fit the PS12 m/c.
Brake rebuilders also state they can't help.
Fixing/component suppliers state they don't supply the DIN984 type.
I did find out that the Honda CB500 brake m/c uses the same circlip and it was available separately with its own part number! (90651-MAK-003)
However, all Honda parts suppliers are coming back that it is no longer available/discontinued by manufacturer & nobody has any stock.
I found some Chinese manufacturers who can supply these but their minimum order is 5-10 thousand!!! With no negotiation as it is not a stock item and would be manufactured on acceptance of the order.
So, anyone on here know where I might be able to get 2-3 of these 16mm internal circlips with extra abutments? (pic below)
Would be much appreciated
Thanks,
Mark
Edited by markie76 on Wednesday 14th June 22:47
That the pads & pistons are moving freely when the lever is pumped suggests that the issue could be air in the system, a ballooning hose OR the master cylinder seals have failed & fluid is passing back when under any pressure which would mean no braking.
If you maintained pressure on the lever did it continue to move towards the handlebar?
As it was also used on another m/cycle you might consider trying breakers.
If the seals have gone & no overhaul kit is available your option may well be a new unit.
If you maintained pressure on the lever did it continue to move towards the handlebar?
As it was also used on another m/cycle you might consider trying breakers.
If the seals have gone & no overhaul kit is available your option may well be a new unit.
GreenV8S said:
I wouldn't have thought it was particularly fussy on dimensions or shape, as long as it will fit in the groove, enough compression to ensure it won't fall out and with a fitted inner diameter smaller than the piston OD.
Yes but the piston end has a 'funky' design where the recess for the actuator rod has a raised lip around it - presumably to prevent contact between rod & circlip. See pics below.
paintman said:
That the pads & pistons are moving freely when the lever is pumped suggests that the issue could be air in the system, a ballooning hose OR the master cylinder seals have failed & fluid is passing back when under any pressure which would mean no braking.
If you maintained pressure on the lever did it continue to move towards the handlebar?
As it was also used on another m/cycle you might consider trying breakers.
If the seals have gone & no overhaul kit is available your option may well be a new unit.
This all surfaced one morning when I set off for my usual commute, pulled the left brake, the lever stopped with the usual resistance but there was no braking action If you maintained pressure on the lever did it continue to move towards the handlebar?
As it was also used on another m/cycle you might consider trying breakers.
If the seals have gone & no overhaul kit is available your option may well be a new unit.
and I had to yank the front harder.The bike has only done 9000km and both hoses look fine - they are braided coated in clear plastic.
When the lever was pulled it would feel as 'normal' travelling about a third of the way, the feeling resistance and stopping at about mid-point.
Having stripped & checked the calliper and bled/reverse bled the system this was my next step to check the seals which visually look ok - nice even lip with no visible damage or deterioration of the rubber.
I have done breaker searches etc but this is where it also gets a bit odd as there seem to be a number of various/variants of the PS12 m/c for big bikes covering handlebar & foot units.
There is a Brembo PS12 rebuild kit for a big bike unit; https://tinyurl.com/y94bgdy9 - none of the parts similar to what's in mine.
Ducati use a PS12 (which looks identical to mine) as a clutch m/c; https://tinyurl.com/ybfeh9m7 - I haven't yet found a rebuild kit via Ducati parts suppliers.
A rear PS12 unit for a MotoGuzzi; https://tinyurl.com/ydefnrkf
Also I don't want to be buying some old & manky unit which may be close to failure.
I understand technology moves on and old models become obsolete. It's not like I'm trying to buy a new 1985 Ford Capri in Beige but a simple engineering component.
There are suppliers who stock almost everything for my 1973 classic car so why not the same for a component in a brake unit produced by one of the worlds biggest names in braking and fitted to millions of vehicles
Edited by markie76 on Monday 19th June 15:55
robinessex said:
Stick in a standard circlip instead. In 50 yrs in the engineering business, I've yet to come across a reason for the internal 'prongs'. Once it's in position, the piston isn't going to come out. Which is all that's required.
I have tried a standard circlip and it seems only the eyelets are achieving reasonable overlap of the bore to hold in the piston - see pics below. The main body (opposite the eyelets) of the circlip seems to have minimal overlap onto the piston to hold it in.
Therefore I don't have full confidence that with repeated use, hundreds to thousands of times a week/month the circlip eyelets won't suffer excessive stress leading to a possible failure.
From seeing that picture what is your opinion?
markie76 said:
I have tried a standard circlip and it seems only the eyelets are achieving reasonable overlap of the bore to hold in the piston - see pics below.
The main body (opposite the eyelets) of the circlip seems to have minimal overlap onto the piston to hold it in.
Therefore I don't have full confidence that with repeated use, hundreds to thousands of times a week/month the circlip eyelets won't suffer excessive stress leading to a possible failure.
From seeing that picture what is your opinion?
Have you worked out how much force the retainer needs to apply to that piston? My guess is not very much at all. If I were you I'd stick it back together with that circlip and try to figure out why the braking system stopped working. I can't see how that circlip would have had anything to do with the symptoms you described so this might be the least of your problems. (In case it's any help, I would be looking for bore damage / contamination causing the slave piston to jam in the bore.)The main body (opposite the eyelets) of the circlip seems to have minimal overlap onto the piston to hold it in.
Therefore I don't have full confidence that with repeated use, hundreds to thousands of times a week/month the circlip eyelets won't suffer excessive stress leading to a possible failure.
From seeing that picture what is your opinion?
egomeister said:
YES YES YES ! ! !Well sort of - I have contacted springmasters before (as well as albionspring, calebcomponents, pinstructure, barnwell) and got the usual private buyer brickwall.
Springmasters minimum order will be £15 for 20 circlips.
Caleb can do 30 for £10.25.
Box of 180 assorted circlips on the bay £4.19.
Local independent car parts shop (yes they still exist!) normal circlips 29p - £1 depending on size
To avoid buying 20 or 30 and meeting a 'minimum order' charge, I might as well risk buying a m/c rebuild kit for £15-£17 which look very similar to my m/c internals and then I'll get the circlip and additional bits to rebuild it.
The KTM kits look like a match; https://tinyurl.com/y9phlxad - I just need to find a way to cross match the m/c.
Anyone know someone with a KTM SX dirt bike?
GTIAlex said:
That's an e-clip - I don't think it would be possible to fit one into the circlip channelmarkie76 said:
egomeister said:
YES YES YES ! ! !Well sort of - I have contacted springmasters before (as well as albionspring, calebcomponents, pinstructure, barnwell) and got the usual private buyer brickwall.
Springmasters minimum order will be £15 for 20 circlips.
Caleb can do 30 for £10.25.
Box of 180 assorted circlips on the bay £4.19.
Local independent car parts shop (yes they still exist!) normal circlips 29p - £1 depending on size
To avoid buying 20 or 30 and meeting a 'minimum order' charge, I might as well risk buying a m/c rebuild kit for £15-£17 which look very similar to my m/c internals and then I'll get the circlip and additional bits to rebuild it.
The KTM kits look like a match; https://tinyurl.com/y9phlxad - I just need to find a way to cross match the m/c.
Anyone know someone with a KTM SX dirt bike?
Even ordering business to business you normally come up against minimum orders, i've often ordered extras/different parts "for stock" just to bulk up the order... perhaps you can start reselling them and claw your money back, haha. Even if it costs you £20 it's still better than no bike...
GreenV8S said:
Have you worked out how much force the retainer needs to apply to that piston? My guess is not very much at all. If I were you I'd stick it back together with that circlip and try to figure out why the braking system stopped working. I can't see how that circlip would have had anything to do with the symptoms you described so this might be the least of your problems. (In case it's any help, I would be looking for bore damage / contamination causing the slave piston to jam in the bore.)
The spring behind it is fairly beefy.Well, I have inspected the m/c bore and it is nice and smooth with no damage. Just 2 glossy areas presumably where the seals are seated and engage from.
There were a few bits of what looked like bits of white crusty sediment at the rear of the bore where the fluid exits into the hose.
I have cleaned these out and have no idea what they could have been - brake fluid can't form sediment can it?
So now it is ready for further testing subject to the circlip.
I just want to avoid doing it with the normal one in place and finding the problem gone but then having to take it apart again once I get hold of the correct circlip.
If the pressure issue isn't resolved then nothing lost.
I'm really fed up of the word circlip
egomeister said:
I'm guessing the assorted boxes probably wouldn't contain circlips in this more unusual form.
Even ordering business to business you normally come up against minimum orders, i've often ordered extras/different parts "for stock" just to bulk up the order... perhaps you can start reselling them and claw your money back, haha. Even if it costs you £20 it's still better than no bike...
Correct, the assorted boxes are just all plain.Even ordering business to business you normally come up against minimum orders, i've often ordered extras/different parts "for stock" just to bulk up the order... perhaps you can start reselling them and claw your money back, haha. Even if it costs you £20 it's still better than no bike...
I did think of opening a 16mm DIN984 circlip shop on ebay to recoup the cost, perhaps make a profit. But in my business analysis I concluded demand might not be there.
The bike has an engine issue at the moment so is off the road anyway and I'm not currently commuting.
I even tried asking for a paid sample where I would send them a SAE, can you guess what they said...
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