Ducati Sporting Club UK > Model Specific - Discussion, Technical Problems and Help > General Motorcycles only > techie question- working out the correct size master cylinder bore for calliper size and type.

[andyb]

I understand there is a way of working out the size of master cylinder bore required for the size and type of callipers fitted. (ratio)

This results in a figure comparable to other bikes.

I wonder what is the best figure to obtain and why? Shazzam...............

[ali]

Search on Shazzam's posts. He did great bit on exactly this a while back. 19x18 for twin four-pots, and 16x18 for a single as a basic rule. Depends on whether you want more initial bit or progressive feel.

Ali

[Iconic944ss]

Good question !!!!

Any ideas about bloody spongey 6-pot calipers

Frank

PLEASE !!!!!!

[andyb]

So the formula is the area of the calliper pistons divided by the area of the master cylinder.

A std fireblade is around a figure of 34.5. An nc 30 is around 31.5.

Brake levers are about feel.

Too great a number and you have a hard lever, but no feel.

Too low a number and you have loads of feel but of course too much travel!

I would suggest from what your saying Frank, your master cylinder is too small a bore to cope with your 6 pots. ( what a std 16mm ducati master cylinder bore?)

Thats easy to see when you think of the amount of fluid required to move all those extra calliper pistons.

I bet your ratio is low 20's.

Brembo 19/18 master cylinder to sort me thinks.......