Ducati Sporting Club UK > DesmoDue Race Series > DesmoDue - General Questions and Chat > help brakes

[Dominic Clegg]

Just spent all day and a lot of brake fluid on trying to fit twin brakes to the front of my bike. i have a 1994 ducati 600 ss. i got off ebay a 600ss disk and the right hand caliper from a 750ss i also got a twin bolt to fit my master cylinder so i could run two line from it. but after an age of trying several ways to bleed the system the brakes were still very spongy. so i tested each line and each caliper in turn and when i did that they were fine rock solid. so what am i doing wrong, do i need to fit a different master cylinder. i.e one off a 900ss or from a 916.

im real ****ed off i through this was going to be a simple job

pleases help

[GlennG]

you will normally need to change your master cylinder for a larger internal bore item if adding an extra caliper.

I'm not sure what size my 620 twin disc master cylinder is couldn't see any markings on it just now apart from brembo, maybe someone more knowlesgable will be able soon to help you out with an appropriate size required.

In the meantime this might help you if you know what size your caliper pistons are, you can then select an appropriate size master cylinder :

http://www.ducatimeccanica.com/brake_ratios.html

[Dominic Clegg]

i think i need a master cylinder then feel a bit stupid now. trying to get my little cylinder to do twice the work it was designed for oh well time to spend yet more money

[skidlids]

yep bigger mastercylinder is required, on this we are not tied to OE Ducati equipment so any mastercylinder off and bike using two four pot calipers will do including the non remote reservoir ones as found on 620 Monsters and the non injected 750SS. Most people do tend to go for a 916/996 type but they're not that cheap to pick up lately.

[Dominic Clegg]

thank you kevin

[Rob B]

I have one (Ducati type - adj span etc.) that I have just pulled off an Bimota SB8. Good nick etc. Also, pair of 65mm spacing gold callipers too.

Rgds, Rob

[antonye]

Yep, deffo the master cylinder as it's only designed for one caliper!

I've got a 916 master cylinder with remote resevoir here that is yours for £50 if you want it - I used it last year on my twin disk system.

[Dominic Clegg]

ill let you know how i get on and ill get back to you if not. ill sort something at brands

[Maxypriest]

I use a Kwacka 636 M/C and it works a treat. Plus they are cheap on the bay. You will need a Kwacka banjo bolt, at it's different to duke ones - thats all.