Front Master Cylinder Questions

[The Bearded Duc]

I was thinking of changing out my brake and clutch master cylinders. I have the coffin masters right now but want the "pee cup" style. Would this be considered an improvement or does it really matter?

Also, after browsing Yoyodyne's website for said masters I noticed they have different bores for brakes and clutch. For the brakes there are 13mm and 16mm and for the clutch, 12mm and 13mm. How do I know which to get?

Thanks to all!

[Nomad]

There is more you can screw up when installing the 'pee cup' style, coffins are pretty idiot proof.  But that said, it isn't really complicated.  IMO it is definitely a cosmetic improvement, I don't like the look of the coffins.  Depending on the MC's you get it could be legitimate upgrade, or it could be simply cosmetic.

[ducatiz]

The goldline peecups are not a performance upgrade, esp if you get the same diameter piston.  The only upgrade is the ability to add adjustable levers.

Get radial masters and then you have a performance upgrade.  And Pee Cups too.

[ducpainter]

The goldline peecups are not a performance upgrade, esp if you get the same diameter piston.  The only upgrade is the ability to add adjustable levers.

Get radial masters and then you have a performance upgrade.  And Pee Cups too.

They make large pivot adjustable levers so there's no advantage to the pee cups.

The coffin masters crash very well.

[stopintime]

Which calipers do you have?

[ducpainter]

To the OP...

if you have dual front calipers you want 16mm master...15 is for a single.

Most Duc clutches are 13mm master I think.

[ducatiz]

There are some calculators on the web for figuring out which master is the best, but you have to really know your numbers to use them.  Here is a good chart I found a while back and have linked:



If you start with your current brakes, you get an idea of their performance by looking at the ratio, which is usually slave pistons mm^2 : master piston mm^2.  The lower the ratio number, the more you move the slave pistons for each 1mm of lever travel -- theoretically meaning you can brake harder, but you lose "finesse" in the braking.   

[The Bearded Duc]

Get radial masters and then you have a performance upgrade.  And Pee Cups too.

Is the performance with radial masters that noticeable even without upgrading the calipers, lines, and rotors?

The coffin masters crash very well.

I know this really well!   
I actually like the lower profile of the coffins too. So, there's really no benefit to the pee cups, performance wise?

Which calipers do you have?

I've got the OEM gold 4 piston calipers.

[ducatiz]

Is the performance with radial masters that noticeable even without upgrading the calipers, lines, and rotors?

the stock lines are actually pretty good, and if you swap rotors with the same material (stainless for stainless) you wont see much improvement there either.  the main question is which calipers you have and you've said you have the goldline 4piston type.  unless you upgrade to the 4 pad SBK type, you will only see a quicker and more controllable grab with the radial master.  4 piston calipers will give you better performance -- now radial calipers, that's the gold standard...

[stopintime]

My upgrade impressions:

1. 320 rotors, 16mm coffin and Goldline 4 pistons.   WOW (Coming from 300mm, 15mm coffin and 2 pistons)
2. 320 full floating Brembo HP and sintered pads.  WOW again - nearly the same wow-factor.
3. Radial master.  Better, but not worth it for legal street riding.

I think you're not gaining much from Goldline pee-cup masters and that you have to be very hungry for only small improvements to justify a radial master.
Best bang for buck, IMO, would be 4 piston 4 pads (999 style) and sintered pads - followed by full floating rotors.
I don't know if a new master is required with the 4 pads.....

Fresh fluid, clean rotors and a good bleed job will never be wrong either.

[The Bearded Duc]

the stock lines are actually pretty good, and if you swap rotors with the same material (stainless for stainless) you wont see much improvement there either.  the main question is which calipers you have and you've said you have the goldline 4piston type.  unless you upgrade to the 4 pad SBK type, you will only see a quicker and more controllable grab with the radial master.  4 piston calipers will give you better performance -- now radial calipers, that's the gold standard...

Ok so, my set-up currently is....

Coffin clutch master
Coffin brake master
Cheapy adjustable levers from Monsterparts
Stock clutch line
Stock brake line with "Y" splitter to the calipers
4 piston calipers
Stock brembo 320mm rotors (dual)

I'm gathering this set-up is pretty good, and it feels pretty good to me as well. So any changes need only to be cosmetic?

[stopintime]

Cosmetic changes have happened before 
You wouldn't be the first.

, but maybe you would be happier spending on something that will make more of an improvement?

I don't know and I'm NOT the right person to lecture anyone about sensibility

[The Bearded Duc]

, but maybe you would be happier spending on something that will make more of an improvement?

I just got back from Pro Italia and one of the parts guys recommended that the only change he could think of, unless I wanted to go balls out, would be two brake lines. One to each caliper instead of the "Y", he said if would give more of a progressive feel and less lag in brake response.

Guess I might just do that, see what I think. Anyone else have any experience with this?

[ducatiz]

I just got back from Pro Italia and one of the parts guys recommended that the only change he could think of, unless I wanted to go balls out, would be two brake lines. One to each caliper instead of the "Y", he said if would give more of a progressive feel and less lag in brake response.

Guess I might just do that, see what I think. Anyone else have any experience with this?

there are three basic lines for 2 calipers:

separate lines : | |

H line:  h (two lines joined at a banjo)

T line:  looks like a sideways T i.e. â"œ

The T line is common on monsters from teh factory and the dual line is common on teh SS and the h line is on SBKs

I haven't found there is a huge bit of difference in the feel:  you are still pushing Xmm^2 amount of fluid in the line to Ymm^2.  the difference in any feel will vary mostly due to the amount of non-brake fluid you have in the line.  in other words, ceteris paribus, if you have perfect fluid in your lines, all of them should feel the same since hydraulic action works the same regardless of where the branches in the columns of fluid occur.

Put it this way:  The master cylinder pushes a column of fluid into two calipers.  The amount of fluid pushed is the same regardless how many hoses you have or how long they are.

There might be tiny differences in the amount of energy required to push 10 separate 1/8" hoses (which then join into 2 groups of 5) but I doubt you will feel the difference in 2 hoses versus a T hose since the difference in the column length is negligible.

my brain hurtz

[The Bearded Duc]

there are three basic lines for 2 calipers:

separate lines : | |

H line:  h (two lines joined at a banjo)

T line:  looks like a sideways T i.e. â"œ

The T line is common on monsters from teh factory and the dual line is common on teh SS and the h line is on SBKs

I haven't found there is a huge bit of difference in the feel:  you are still pushing Xmm^2 amount of fluid in the line to Ymm^2.  the difference in any feel will vary mostly due to the amount of non-brake fluid you have in the line.  in other words, ceteris paribus, if you have perfect fluid in your lines, all of them should feel the same since hydraulic action works the same regardless of where the branches in the columns of fluid occur.

Put it this way:  The master cylinder pushes a column of fluid into two calipers.  The amount of fluid pushed is the same regardless how many hoses you have or how long they are.

There might be tiny differences in the amount of energy required to push 10 separate 1/8" hoses (which then join into 2 groups of 5) but I doubt you will feel the difference in 2 hoses versus a T hose since the difference in the column length is negligible.

my brain hurtz

So the different line configurations is just Ducati's way of saying "We're gonna run the lines any way we want"?