Radial master cylinders - both clutch and brake
Discussion
After a bit of help here, as I'm googling all sorts and not getting far.
Got an issue with my Dorsoduro 750 forks, which is a long story but has ended up at the point that it's now got the forks off a 1200 and a set of upgrade Brembo calipers, which I fitted and bled at the weekend. Result is no air in the system, but the lever is travelling all the way to the throttle grip. The Dorsoduro calipers are also by Brembo but have smaller pistons, and therefore a smaller master cylinder than usual, so now my calipers are bigger, I'm running out of lever travel before the pistons have travelled all the way to the discs.
Have tried to find Dorso 1200 calipers but there's none around, and TBH I'd rather spend my money on better master cylinders and levers than on worse calipers than I've now got fitted.
So I need a larger master cylinder, and on the Dorso the m/cyl casting also mounts the hand guard and the mirror, which means I'll need to swap those too. This isn't the end of the world as I always intended to fit guards with LED indicators, as the OE indicators sag and look sad, and are overall a bit crappy. Mirrors, well meh, we can possibly do without those for the sort of use my bike gets.
In the spirit of don't replace, upgrade, I'd like the replacement to be a radial m/cyl. And of course if I renew the brake, I need to renew the clutch too. From research so far, I need 19mm brake, 16mm clutch.
Much as I'd like a pair of Brembo radials, you're looking at £550 quid the pair once you've added pisspots and a brake switch. Plus hand guards, plus mirrors. Going for "Braking" brand from Italy (who knows...??) is still £400+ once here. HEL are £200 apiece plus pots etc. Or there's the Chinesium route for £40 - not on your (my) life.
Hence wanting to find a secondhand pair - I guess most OE radials are Brembo or Nissin?
So (thanks for getting this far) are there any sports bikes out there with those sizes of radial master cylinders? I've found quite a few with the right brake cyl but with a cable clutch. And sadly just don't know enough about modern sports bikes to know which are hyd clutch.
Cheers for any pointers.
Got an issue with my Dorsoduro 750 forks, which is a long story but has ended up at the point that it's now got the forks off a 1200 and a set of upgrade Brembo calipers, which I fitted and bled at the weekend. Result is no air in the system, but the lever is travelling all the way to the throttle grip. The Dorsoduro calipers are also by Brembo but have smaller pistons, and therefore a smaller master cylinder than usual, so now my calipers are bigger, I'm running out of lever travel before the pistons have travelled all the way to the discs.
Have tried to find Dorso 1200 calipers but there's none around, and TBH I'd rather spend my money on better master cylinders and levers than on worse calipers than I've now got fitted.
So I need a larger master cylinder, and on the Dorso the m/cyl casting also mounts the hand guard and the mirror, which means I'll need to swap those too. This isn't the end of the world as I always intended to fit guards with LED indicators, as the OE indicators sag and look sad, and are overall a bit crappy. Mirrors, well meh, we can possibly do without those for the sort of use my bike gets.
In the spirit of don't replace, upgrade, I'd like the replacement to be a radial m/cyl. And of course if I renew the brake, I need to renew the clutch too. From research so far, I need 19mm brake, 16mm clutch.
Much as I'd like a pair of Brembo radials, you're looking at £550 quid the pair once you've added pisspots and a brake switch. Plus hand guards, plus mirrors. Going for "Braking" brand from Italy (who knows...??) is still £400+ once here. HEL are £200 apiece plus pots etc. Or there's the Chinesium route for £40 - not on your (my) life.
Hence wanting to find a secondhand pair - I guess most OE radials are Brembo or Nissin?
So (thanks for getting this far) are there any sports bikes out there with those sizes of radial master cylinders? I've found quite a few with the right brake cyl but with a cable clutch. And sadly just don't know enough about modern sports bikes to know which are hyd clutch.
Cheers for any pointers.
Good call - a bit more searching through ebay has made me wonder if ducati stuff is a good option. Just found a pair of panigale m/cyls and levers and pots that I've sent an offer on.
Was starting to look down the road of japanese stuff but it's pretty obvious when you think about it, higher spec italian bikes are likely to have brembo m/cyls.
Was starting to look down the road of japanese stuff but it's pretty obvious when you think about it, higher spec italian bikes are likely to have brembo m/cyls.
Braking is a pretty well-known company (well, I've heard of them 
).
https://www.braking.com/en/
Owned by Sunstar, who make a lot of OEM stuff and aftermarket sprockets.
).https://www.braking.com/en/
Owned by Sunstar, who make a lot of OEM stuff and aftermarket sprockets.
FNG said:
So (thanks for getting this far) are there any sports bikes out there with those sizes of radial master cylinders? I've found quite a few with the right brake cyl but with a cable clutch. And sadly just don't know enough about modern sports bikes to know which are hyd clutch.
Don't know about Aprilia but I have radial master cylinders on all my bikes; 2 Ducatis and the old Guzzi.On the Guzzi just the brakes (clutch is cable), using a Brembo 15 RCS (15mm bore with adjustable 18 or 20 mm pivot) which is perfect for the twin, OEM 2 pot calipers.
916 has Brembo 19x20 Radial master (non adjustable) for the brakes - 2x Brembo HPK radial, 4 pot (hydraulic clutch is still using the OEM master).
Monster 900 has Brembo RCS 19 (19mm bore with adjustable 18 or 20 mm pivot) for the brakes - 2x Brembo M4 billet radial, 4 pot and Brembo RCS 16 (16mm bore with adjustable 18 or 20 mm pivot) for the hydraulic clutch - I use the 18mm pivot for a better 'feel' but the 20mm works well too.
I can say that for twin 4 pot calipers that I have, the 19mm bore is perfect though some newer (Panigale?) use smaller bore calipers so require smaller master cylinders? and the 18/20mm lever adjustment can get a little more feel by using the shorter setting but the longer also works well - in fact, by luck I think it's best for my setups as whilst the HPK calipers are 'better' (more progressive) than the M4 which have more initial bite and so the 18mm lever gives a more sensitive feel to otherwise quite fierce initial braking, both Ducati caliper/master setups give as much (2-finger) braking power as you'll ever need.
As for the clutch setup, this will also depend on what slave cylinder is fitted plus, the strength of the clutch spring setup etc. but the 15 RCS works perfectly with an Oberon slave and actually gives a lighter pull than the 916 with OEM master and upgraded 'Evoluzione' slave cylinder and it does have the 2 settings (18/20) to chose between reduced pull or better plate separation.
How that relates to the Aprilia though I can't say but I would think the setup is similar to Ducati?
Edited by catso on Tuesday 6th September 10:56
FNG said:
Good call - a bit more searching through ebay has made me wonder if ducati stuff is a good option. Just found a pair of panigale m/cyls and levers and pots that I've sent an offer on.
Was starting to look down the road of japanese stuff but it's pretty obvious when you think about it, higher spec italian bikes are likely to have brembo m/cyls.
The mounting bracket for the Master Cylinder also holds the hand guards (which have LED indicators) and mount the mirrors (which are quite nice)… might resolve a few of your wants with one lucky ebay find…..Was starting to look down the road of japanese stuff but it's pretty obvious when you think about it, higher spec italian bikes are likely to have brembo m/cyls.
I've not been over the moon with the feel of the brakes on my KTM 1290 GT, it's got Brembo callipers and Brembo branded master cylinder. It worked perfectly well, nothing wrong and usually wouldn't complain but I wanted better feel. So I fitted a Brembo 17RCS master earlier this year and it's completely transformed the front brake. The feel is very progressive and sensitive, really nice and more powerful than the original. Just makes the bike a little bit more enjoyable.
I know other master cylinders will be perfectly good but the RCS units really are top drawer. I'd definitely recommend one of these if you can stretch to it. I bought mine from Carpimoto in Italy, under £300 including carriage and vat and tax etc, all delivered in a couple of days. If you tell them which callipers you have they will match the master with the piston size.
Edit to add the RCS master can also be supplied with a mirror mount on it in various threads and also takes the stock KTM brake light switch so it's really plug and play.
I know other master cylinders will be perfectly good but the RCS units really are top drawer. I'd definitely recommend one of these if you can stretch to it. I bought mine from Carpimoto in Italy, under £300 including carriage and vat and tax etc, all delivered in a couple of days. If you tell them which callipers you have they will match the master with the piston size.
Edit to add the RCS master can also be supplied with a mirror mount on it in various threads and also takes the stock KTM brake light switch so it's really plug and play.
Edited by SteveKTMer on Tuesday 6th September 11:33
catso said:
Don't know about Aprilia but I have radial master cylinders on all my bikes; 2 Ducatis and the old Guzzi.
On the Guzzi just the brakes (clutch is cable), using a Brembo 15 RCS (15mm bore with adjustable 18 or 20 mm pivot) which is perfect for the twin, OEM 2 pot calipers.
916 has Brembo 19x20 Radial master (non adjustable) for the brakes - 2x Brembo HPK radial, 4 pot (hydraulic clutch is still using the OEM master).
Monster 900 has Brembo RCS 19 (19mm bore with adjustable 18 or 20 mm pivot) for the brakes - 2x Brembo M4 billet radial, 4 pot and Brembo RCS 16 (16mm bore with adjustable 18 or 20 mm pivot) for the hydraulic clutch - I use the 18mm pivot for a better 'feel' but the 20mm works well too.
I can say that for twin 4 pot calipers that I have, the 19mm bore is perfect though some newer (Panigale?) use smaller bore calipers so require smaller master cylinders? and the 18/20mm lever adjustment can get a little more feel by using the shorter setting but the longer also works well - in fact, by luck I think it's best for my setups as whilst the HPK calipers are 'better' (more progressive) than the M4 which have more initial bite and so the 18mm lever gives a more sensitive feel to otherwise quite fierce initial braking, both Ducati caliper/master setups give as much (2-finger) braking power as you'll ever need.
As for the clutch setup, this will also depend on what slave cylinder is fitted plus, the strength of the clutch spring setup etc. but the 15 RCS works perfectly with an Oberon slave and actually gives a lighter pull than the 916 with OEM master and upgraded 'Evoluzione' slave cylinder and it does have the 2 settings (18/20) to chose between reduced pull or better plate separation.
How that relates to the Aprilia though I can't say but I would think the setup is similar to Ducati?
Hmmm interesting you say the panigale has smaller pistons than usual... i'll need to find out what size as the last thing I need is new levers with the same issue as the ones on the bike!On the Guzzi just the brakes (clutch is cable), using a Brembo 15 RCS (15mm bore with adjustable 18 or 20 mm pivot) which is perfect for the twin, OEM 2 pot calipers.
916 has Brembo 19x20 Radial master (non adjustable) for the brakes - 2x Brembo HPK radial, 4 pot (hydraulic clutch is still using the OEM master).
Monster 900 has Brembo RCS 19 (19mm bore with adjustable 18 or 20 mm pivot) for the brakes - 2x Brembo M4 billet radial, 4 pot and Brembo RCS 16 (16mm bore with adjustable 18 or 20 mm pivot) for the hydraulic clutch - I use the 18mm pivot for a better 'feel' but the 20mm works well too.
I can say that for twin 4 pot calipers that I have, the 19mm bore is perfect though some newer (Panigale?) use smaller bore calipers so require smaller master cylinders? and the 18/20mm lever adjustment can get a little more feel by using the shorter setting but the longer also works well - in fact, by luck I think it's best for my setups as whilst the HPK calipers are 'better' (more progressive) than the M4 which have more initial bite and so the 18mm lever gives a more sensitive feel to otherwise quite fierce initial braking, both Ducati caliper/master setups give as much (2-finger) braking power as you'll ever need.
As for the clutch setup, this will also depend on what slave cylinder is fitted plus, the strength of the clutch spring setup etc. but the 15 RCS works perfectly with an Oberon slave and actually gives a lighter pull than the 916 with OEM master and upgraded 'Evoluzione' slave cylinder and it does have the 2 settings (18/20) to chose between reduced pull or better plate separation.
How that relates to the Aprilia though I can't say but I would think the setup is similar to Ducati?
Edited by catso on Tuesday 6th September 10:56
Great feedback on the rest, many thanks for taking the time.
I'm happy to look at upgrade calipers later - the ones that came with my replacement forks are scuffed, and it's a 110mm bolt spacing which I think is common, so replacements won't be that hard to find. But I really need a solution asap otherwise I'll have lost the rest of the summer - bike's been off the road with this issue since March (with a house move getting in the way in between) - it's been a long old saga.
gareth_r said:
Braking is a pretty well-known company (well, I've heard of them ).
https://www.braking.com/en/
Owned by Sunstar, who make a lot of OEM stuff and aftermarket sprockets.
Thanks. I think there was just something about the name, and/or the look of them, that was making me think designed in Italy, made in China. If they're decent and I can get them new for about £300 it might be the right way to go.).https://www.braking.com/en/
Owned by Sunstar, who make a lot of OEM stuff and aftermarket sprockets.
Oh and the Dorsoduro brake m/cyl is 14mm diameter.
When your average sports bike (which my calipers are taken from) has an 18 or 19mm bore, no wonder I'm running out of travel.
Panigale looks like it's 16mm which I'm doubtful is big enough.
Multistrada is 18mm which looks sensible.
But I need to whip a caliper off, measure the piston diameter, and calculate the ratio.
When your average sports bike (which my calipers are taken from) has an 18 or 19mm bore, no wonder I'm running out of travel.
Panigale looks like it's 16mm which I'm doubtful is big enough.
Multistrada is 18mm which looks sensible.
But I need to whip a caliper off, measure the piston diameter, and calculate the ratio.
Edited by FNG on Tuesday 6th September 11:42
SteveKTMer said:
Edit to add the RCS master can also be supplied with a mirror mount on it in various threads and also takes the stock KTM brake light switch so it's really plug and play.
You can also get the mirror mount bracket as a separate piece, I did this on the Guzzi as the RCS came without but the back piece of the clamp bracket is all that's required, at least for threaded type mirrors.RCS has a built-in brake light switch whilst the older 19x20 Radial on my 916 doesn't have the provision to fit one at all (think it was originally a race part) so I needed to use a pressure switch/banjo fitting.
SteveKTMer said:
I've not been over the moon with the feel of the brakes on my KTM 1290 GT, it's got Brembo callipers and Brembo branded master cylinder. It worked perfectly well, nothing wrong and usually wouldn't complain but I wanted better feel. So I fitted a Brembo 17RCS master earlier this year and it's completely transformed the front brake. The feel is very progressive and sensitive, really nice and more powerful than the original. Just makes the bike a little bit more enjoyable.
I know other master cylinders will be perfectly good but the RCS units really are top drawer. I'd definitely recommend one of these if you can stretch to it. I bought mine from Carpimoto in Italy, under £300 including carriage and vat and tax etc, all delivered in a couple of days. If you tell them which callipers you have they will match the master with the piston size.
Edit to add the RCS master can also be supplied with a mirror mount on it in various threads and also takes the stock KTM brake light switch so it's really plug and play.
There is that concern in the back of my mind - Brembo as supplied to OE to broadly suit all riders isn't necessarily the same as Brembo aftermarket intended as a performance upgrade for more skilled or more enthusiastic.I know other master cylinders will be perfectly good but the RCS units really are top drawer. I'd definitely recommend one of these if you can stretch to it. I bought mine from Carpimoto in Italy, under £300 including carriage and vat and tax etc, all delivered in a couple of days. If you tell them which callipers you have they will match the master with the piston size.
Edit to add the RCS master can also be supplied with a mirror mount on it in various threads and also takes the stock KTM brake light switch so it's really plug and play.
Edited by SteveKTMer on Tuesday 6th September 11:33
I would possibly spring for a RCS19 if not for the fact I couldn't just get one! and then on a £3k bike, and alongside the £500 I've just put into the forks, another £600 doesn't make sense.
I like the mirror mount on the m/cyl clamp though. One to keep in mind for sure.
The Dorso m/cyl piston is 14mm and the correct sized one for the calipers I think I've got is 19mm, so it's only got 54% of the cross section that it needs. So the lever needs to travel nearly twice as far - 1.85x normal lever travel - to displace the same amount of fluid.
The lever is definitely firming up as it should but over a loooong travel - and takes a fair bit of pull to get it to touch the grip, but doesn't need abnormal force.
I'll be getting into the garage to check the piston size later, so will double check the pistons aren't retracting. But as I say the lever feels like it's firming up properly, not with a mass of slack on initial application - it's just not firming up as quickly as it needs to.
The lever is definitely firming up as it should but over a loooong travel - and takes a fair bit of pull to get it to touch the grip, but doesn't need abnormal force.
I'll be getting into the garage to check the piston size later, so will double check the pistons aren't retracting. But as I say the lever feels like it's firming up properly, not with a mass of slack on initial application - it's just not firming up as quickly as it needs to.
FNG said:
The Dorso m/cyl piston is 14mm and the correct sized one for the calipers I think I've got is 19mm.
Assuming 2 x 4 pot calipers then that master is way too small. My old Guzzi needs a 16mm for 2 x 2 pot, originally fitted with a 13mm for one caliper only (originally had linked brakes with one front + one rear on a 16mm rear M/C and the other front by itself).Unless you've got the latest fandangled Panigale/race type calipers (M50 IIRC) then I agree, you probably need a 19mm.
rodericb said:
Whoah - I think you'd have huge pistons in the calipers and tiniest master cylinder ever made to actually "run out of pump"! Are they truly bled? Are the pistons being sucked back into the caliper?
This!My bike has something like 8 30mm? pistons in the calipers and an 18mm master cylinder.
That's an area ratio of about 22:1
The lever travel is partly taken up by the MC piston moving to cover the feed hole.
The MC piston then moves a few mm and the pads move a fraction of a mm.
Pistons are pulled off the disc by the rubbery nature of the seals. They may also be knocked back by warped discs or floating discs which float too much!
Maybe worth checking the MC is not massively out of adjustment, too much of the piston motion before the pressure seal closes the feed hole IYSWIM?
So the piston diameter is 34mm, giving me a ratio of 47.2:1
For context, a wooden feeling brake with little travel or feel is around 20:1 and a feelsome but soft brake is around the 30:1 mark.
Needless to say 47:1 is way out there and needs a larger m/cyl.
A 19mm piston gets it to 25.5:1 in the sweet spot.
For context, a wooden feeling brake with little travel or feel is around 20:1 and a feelsome but soft brake is around the 30:1 mark.
Needless to say 47:1 is way out there and needs a larger m/cyl.
A 19mm piston gets it to 25.5:1 in the sweet spot.
FNG said:
A 19mm piston gets it to 25.5:1 in the sweet spot.
https://www.ebay.co.uk/itm/115327628953?epid=25031...
You know it makes sense.
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