Berlin Germany
Registered
Clutch+Brake master bore size?
- Thread starter murphc13
- Start date
ottafish
Registered
There is, (don't know if he still is) a guy who floats around the DUcati forums called Shazaam. He has some great posts about brakes and ratios..
Here's a couple of small posts..
------------------------------
A braking system needs to establish the closest linear relationship possible between the force applied to the brake lever and the actual deceleration of the bike. Stopping power is technically easy to achieve, but achieving it along with good proportional braking response is very complex. This, I feel, is the major factor influencing braking quality.
For example, it is of fundamental importance for braking safety and performance that the rider should know, in advance, that a force of 500 grams on the brake lever will give a certain deceleration of the machine, and that a force of 1,000g will result in twice the deceleration, regardless of the conditions (beginning or end of braking, hot or cold, dry or wet).
So, often the advantage of upgrading a braking system is not only greater power. The improvement in proportional response is equally important, as it allows the rider to control and gauge the braking power that's applied, as a function of the conditions of adhesion (grip). This represents a considerable improvement in safety on both road and track.
The modulation characteristics or "feel" are determined by the ratio of the total caliper piston area to the master cylinder piston area. If you change the master cylinder piston size you change this ratio.
-----------------------------
The larger the bore of the master cylinder used with a set of calipers, the less lever movement needed and the greater lever force needed to achieve a given deceleration of the bike. Taken to an extreme the lever feels “wooden”.
Conversely, the smaller the bore of the master cylinder used with a set of calipers, the more lever movement needed and the less lever force needed to achieve a given deceleration of the bike. Taken to an extreme the lever feels “soft”.
Good modulation characteristics strike a balance between these two lever feels. Here are the modulation characteristics for a range of caliper piston area: master cylinder piston area ratios.
Soft feel — 30:1
Best feel — 27:1
Firm feel — 23:1
Wooden feel — 20:1
For example, the rider with the 996R having 34/34 calipers and using a 1098 19 mm diameter master cylinder experienced a 7263:283.5 or a 25.6:1 ratio — quite nice.
On a 996 with 30/34 caliper the 1098 MC produces a 6459:283.5 or a 22.7:1 ratio. Stock 996 is 6459:201.6 = 32:1. An overly soft feel on a street bike is Ducati erring on the side of rider safety and to reduce lock-ups during emergency braking.
---------------------------
Many people lack an understanding of the importance of master cylinder to wheel cylinder ratios. This critical ratio is of paramount importance in determining "feel". It has been my experience that there is a "sweet spot" in the range. I like ratios in the 27:1 range-2 finger power brakes, feeling some line and/or caliper flex. 23:1 is at the other end of the spectrum-firm. Ratios lower than 20:1 can result a feel so "wooden" as to have a toggle switch effect: nothing happens until the wheel locks. Disc and wheel diameters must be taken into consideration. A 10 inch disc working against an 19" wheel just doesn't have the leverage ratio that a 13 inch disc working a 17" wheel does. The hand lever ratio counts too: witness the adjustable master cylinders from Lockheed and Brembo.
Here's a couple of small posts..
------------------------------
A braking system needs to establish the closest linear relationship possible between the force applied to the brake lever and the actual deceleration of the bike. Stopping power is technically easy to achieve, but achieving it along with good proportional braking response is very complex. This, I feel, is the major factor influencing braking quality.
For example, it is of fundamental importance for braking safety and performance that the rider should know, in advance, that a force of 500 grams on the brake lever will give a certain deceleration of the machine, and that a force of 1,000g will result in twice the deceleration, regardless of the conditions (beginning or end of braking, hot or cold, dry or wet).
So, often the advantage of upgrading a braking system is not only greater power. The improvement in proportional response is equally important, as it allows the rider to control and gauge the braking power that's applied, as a function of the conditions of adhesion (grip). This represents a considerable improvement in safety on both road and track.
The modulation characteristics or "feel" are determined by the ratio of the total caliper piston area to the master cylinder piston area. If you change the master cylinder piston size you change this ratio.
-----------------------------
The larger the bore of the master cylinder used with a set of calipers, the less lever movement needed and the greater lever force needed to achieve a given deceleration of the bike. Taken to an extreme the lever feels “wooden”.
Conversely, the smaller the bore of the master cylinder used with a set of calipers, the more lever movement needed and the less lever force needed to achieve a given deceleration of the bike. Taken to an extreme the lever feels “soft”.
Good modulation characteristics strike a balance between these two lever feels. Here are the modulation characteristics for a range of caliper piston area: master cylinder piston area ratios.
Soft feel — 30:1
Best feel — 27:1
Firm feel — 23:1
Wooden feel — 20:1
For example, the rider with the 996R having 34/34 calipers and using a 1098 19 mm diameter master cylinder experienced a 7263:283.5 or a 25.6:1 ratio — quite nice.
On a 996 with 30/34 caliper the 1098 MC produces a 6459:283.5 or a 22.7:1 ratio. Stock 996 is 6459:201.6 = 32:1. An overly soft feel on a street bike is Ducati erring on the side of rider safety and to reduce lock-ups during emergency braking.
---------------------------
Many people lack an understanding of the importance of master cylinder to wheel cylinder ratios. This critical ratio is of paramount importance in determining "feel". It has been my experience that there is a "sweet spot" in the range. I like ratios in the 27:1 range-2 finger power brakes, feeling some line and/or caliper flex. 23:1 is at the other end of the spectrum-firm. Ratios lower than 20:1 can result a feel so "wooden" as to have a toggle switch effect: nothing happens until the wheel locks. Disc and wheel diameters must be taken into consideration. A 10 inch disc working against an 19" wheel just doesn't have the leverage ratio that a 13 inch disc working a 17" wheel does. The hand lever ratio counts too: witness the adjustable master cylinders from Lockheed and Brembo.
Master Cylinder to Wheel Cylinder Ratio Chart | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
If you've got money fallin' outa yer a55 Mythos...spend it on something else.
Just MHO. What do you hope to accomplish? A harder,faster,longer skid in a panic stop? Rear brakes are over rated if you ask me (I know,you didn't so I can go fug off right)
the rule of thumb is 70% front brake/30% rear. My stock caliper with a 4 inch extended high performance line does just fine for all occasions. Now if you were a world class super sport racer and wanted/needed ultimate feel for "trail braking" then maybe. I don't know...school me.Rubb.
Holy krap Fish. Some "light reading" for us.
I'm just a stoopid country bumkin..."pull brake,stop bike."You dudes are like super scientist physics guys.
Rubb.
I just went the cheap route Mr.Berlin. Saved a ton of money.
Rubb.
From pip-squeak grip to this...in just 6 short weeks.
Mythos
Registered
The Accossato is a 19 x adjustable 17/18/19 ratio. 19 mm diameter must be the bore and you adjust the stroke to 17, 18 or 19 mm, is that saying it correctly? The adjuster is that square unfinished metal do-jamahicky with the hole in it. Looks like the cap of the lever pivot. No idea how or what tool one would use to turn that.
Thanks, that's what I thought you meant. I'd be more concerned with the amount of lever actuation required to reach the same brake power as before. I sure don't want a brake lever with a lot of throw in it before it reaches max braking. That's what the stock 08 busa has and I end up searching through the throw for the right amount to pull the lever. I like instant grab with a light touch of the fingers and then modulate just a tad harder or lighter hardly moving the lever at all. It's more like feeling the lever than pulling the lever.
To put it simply, instant hard braking is better and safer for me than progressive braking. My 08's brakes are very progressive. There's very little braking pulling the lever just a little. The front wheel locks at about the point where the lever touches the grip. I have to search through the whole throw of the lever to find the degree of braking I want. With my 14, the brakes are just there with a light touch BOOM. It's easy to pull a bit harder or ease off a touch as needed.
I use the rear brake with the front most of the time. If I get into good enough practice sport riding, I only use the front. The main objective with the Berringer floating rear brake MC is looks. It's a cool looking part and I have a cool way to mount the heim joint on each end. One to the rear brake pedal of course, the other to a bolt under the tail frame. As long as it's as powerful as the stocker, that's fine with me but I don't think I want it any less powerful. When it comes to feel, that's what I need to find out before I spend the $400 on a rear MC that I don't really rely on anyway. As with the front brakes, having more travel in the rear brake pedal is not an improvement in my book.If you've got money fallin' outa yer a55 Mythos...spend it on something else.
Just MHO. What do you hope to accomplish? A harder,faster,longer skid in a panic stop? Rear brakes are over rated if you ask me (I know,you didn't so I can go fug off right)
Rubb.
IF I replace the clutch master it would only be to put something more pleasing to the eye.Not for any performance gain.
michael parris heuberger
Registered
Hi. Where are you looking at for Beringer brakes? Frog Specialties. DME has the rear caliper and light rotor and rear master. Look at my avatar that is my rear caliper.
Mythos
Registered
That's why I want to replace the rear brake MC but at the same time, I don't want to have a less powerful rear brake.
@michael parris heuberger I had been corresponding with Evolution Motorcycles about the Berringer floating rear MC but the guy hasn't responded to my last two emails. Maybe I asked too many questions.
The question was exactly what we're discussing on this thread--"how will the bore size effect the brake feel and power." Both DME and Frog offer the 12 mm Berringer rear MC only. The stock MC on my ZX-14 is a 14 mm and 14 mm is recomended for an ISR rear caliper which is what I planned to use on my ZX-14.We talked about your Berringer rear brake caliper. I plan to get Berringer front and rear calipers for the busa. Maybe another floating rear MC too! Heck, I might even throw in the thumb brake!
There's just too damn much cool brake stuff out there!!!!
Last edited:
SSGT_B
Registered
If you've got money fallin' outa yer a55 Mythos...spend it on something else.
Just MHO. What do you hope to accomplish? A harder,faster,longer skid in a panic stop? Rear brakes are over rated if you ask me (I know,you didn't so I can go fug off right)
Rubb.
You don’t trail brake???
michael parris heuberger
Registered
HI. For right now I am using the stock rear MC with my Beringer caliper and DME light weight rotor. I think the rear MC, radiator, external forks and the horn are the only stock parts left on the bikeThat's why I want to replace the rear brake MC but at the same time, I don't want to have a less powerful rear brake.
@michael parris heuberger I had been corresponding with Evolution Motorcycles about the Berringer floating rear MC but the guy hasn't responded to my last two emails. Maybe I asked too many questions.
We talked about your Berringer rear brake caliper. I plan to get Berringer front and rear calipers for the busa. Maybe another floating rear MC too! Heck, I might even throw in the thumb brake!
There's just too damn much cool brake stuff out there!!!!
Mythos
Registered
@michael parris heuberger I'm going to have to do some visualizations of higher pressure and lower volume v lower pressure and higher volume. It seems like one should be about equal to the other. More fuid under less pressure should do what less fluid under more pressure does. I'm not getting why they have different sized bores.
I ride twisties and I don't even trail brake unless I'm getting in good practice. I'm about there now. Unfortunately, summer's coming to an end. One month and then I have to ride in late afternoon because of work schedule. Lots of deer and turkey around that time of year especially as it gets later in the day.
I ride twisties and I don't even trail brake unless I'm getting in good practice. I'm about there now. Unfortunately, summer's coming to an end. One month and then I have to ride in late afternoon because of work schedule. Lots of deer and turkey around that time of year especially as it gets later in the day.
What's a tre'L brake ?
Not so much any more Sarge. The extended arm,the turbo and that fat rollin' thing out back (330 rear tire) sorta limits me in the twisties these days. That coupled with the fact that I couldn't ride worth a krap before this Busa anyway....Rubb.
SSGT_B
Registered
LolWhat's a tre'L brake ?
Rubb.
Just busting your chops. My 1000RR trail braking was a natural occurrence. Haven’t done it on the Busa. Never been that comfortable on this bike.
Mythos
Registered
Thanks, ottafish. That's starting to help describe the feel of various MC bore diameters. As I suspected, it matters a lot how much volume the caliper has. A firm lever with a small caliper might be soft on a large caliper. We can't just pick an MC, we have to take into consideration the requirements of the calipers and find the best happy medium. If I'm going to invest in an expensive MC, I should probably be thinking just as much about what calipers I want to upgrade to. The rotor size even matters. I have 13 inch rotors on the ZX-14 and the diameter is about a half inch larger than stock. It didn't make a lot of difference in braking power. I'd say rotor size is not that big of consideration but caliper displacement is.
I don't really get that chart but the text is helpful. Thanks again.
Berlin Germany
Registered
what the brembo engineer told me:
the braking force is increased by the way you pull the lever closer to the grip
so the lever nerver should reach a "hard" point
get into your - standing - car etc. and push its brake pedal - its counter force is at 1st "soft" and gets "harder" - the way of action is equal.
so for horrible high brake sensivity (at the busa) the bigger piston (19) dia is counter productive
MY personal experience is
that the 17 radial dia combined with the original tokicos is the very best choice.
on the street AND on the reacetrack.
in this combi you get 1/2" of lever way to increase the braking force til its maximum - standing front wheel.
and
the smaller this way becomes the worse the sensivity gets. (brembo engineer)
but what does the nonkey say when he takes a bit bite of the soap? a question of taste.
little story:
a good buddy had an accident with dia 19 by a shock braking while holidays in ireland ca. 12 or 14 years ago.
holidays where definitively off
the bike´s plastics, a gsxr 1000, were heavily damaged
and him and his girl had (only) lots of very aching blue marks.
coming back home , he repaired the bike and directly changed down to dia 17 while giving the dia 19 to the crap box.
thx for his (and her) bad experiences - i accept them and use the dia 17 only.
(so - if someone like the taste of soap he should take a bite.
)
(each at his taste)
the braking force is increased by the way you pull the lever closer to the grip
so the lever nerver should reach a "hard" point
get into your - standing - car etc. and push its brake pedal - its counter force is at 1st "soft" and gets "harder" - the way of action is equal.
so for horrible high brake sensivity (at the busa) the bigger piston (19) dia is counter productive
MY personal experience is
that the 17 radial dia combined with the original tokicos is the very best choice.
on the street AND on the reacetrack.
in this combi you get 1/2" of lever way to increase the braking force til its maximum - standing front wheel.
and
the smaller this way becomes the worse the sensivity gets. (brembo engineer)
but what does the nonkey say when he takes a bit bite of the soap? a question of taste.
little story:
a good buddy had an accident with dia 19 by a shock braking while holidays in ireland ca. 12 or 14 years ago.
holidays where definitively off
the bike´s plastics, a gsxr 1000, were heavily damaged
and him and his girl had (only) lots of very aching blue marks.
coming back home , he repaired the bike and directly changed down to dia 17 while giving the dia 19 to the crap box.
thx for his (and her) bad experiences - i accept them and use the dia 17 only.
(so - if someone like the taste of soap he should take a bite.
)(each at his taste)
ottafish
Registered
I went with a Brembo clutch of a zx14 and it was terrible, and I went back to stock.
Then I went to the generally accepted Brembo 16 and it's friggin awesome.
Well that Brembo I’m referring to has a 15mm bore and 18mm pivot length.I’ve read on here a guy using a 14 bore rcs and you like the 16.
This 15mm bore should be fine so I’d say
Similar threads
