Does anyone KNOW I.e has measured the front master cyl piston/bore size? I ask as I wish to know the ratio of the front brake system, I have changed from 18mm master and 32x32 front calipers to 18mm master and 34x34, people say that Ducatis like the 1098 etc that run M4 (34x34) use a 19mm master which would give me the same ratio as I had before however it would seem so far in all the ones I have checked and the info given widely on the net is WRONG and they in fact use the same 18mm masters thus run a softer ratio than those running 18 into 32x32. Ducati service data also shows those with M4 run a 18mm master.? Ducati or all who Ive asked don't know the size? The ratio of 19mm into 34x34 is more my type of feel as its less progressive and IMO nicer for the road, it's near the sweet spot so to speak. If anyone knows the piston size of say RC8 etc or any other stock bike with M4s do say as I'm interested what ratio they run.
Heres some info I checked with regards to ratios as it was hard to work out why the net shows one thing and my vernier caliper shows another! 18 mm = 254.47 mm2 19 mm + 283.53 mm2 32 x 32 calipers = 6434 mm2 34 x 34 calipers =7263.4 mm2 ratio using 18mm MC with M4 monoblocs- 7263.4: 254.47 = 28.6:1 ratio using 18mm MC with 32 x 32-6434:254.47 = 25.3:1 ratio using 19 mm MC with M4 monoblocs-7463.4:283.53 = 25.6:1 Modulation Characteristics: 30:1 - soft 27:1 - sweet spot 23:1 - firm 20:1 - wooden The 19mm will give a firmer feel at the lever (the same before with 18mm 32 x 32), the 18mm will give a softer feel with the M4s.
I was chatting to the Accossato rep the other day and he said that the Panigale, which uses the M50 monoblocs, needs the 19mm bore due to the extra piston diameter, whereas everything else uses the 18mm bore. This was in conversation about supplying a m/c to a customer. I have the M4 monoblocs on my Hypermotard 1100S (as standard) and I'm pretty sure it's the 18mm m/c as fitted to everything else. The Hyper does have a weird short(er) lever than standard but I assumed this was to fit inside the hand guards rather than to do with lever feel. The way to (quickly) check would be to get the part number from the parts manuals and then cross reference it with something like the standard 848 which used radials but not the mono blocs. You could also check the Panigale M/C and see what that has. It won't tell you the bore but it will tell you if it's the same as others!
The part numbers do vary mate but the piston size seems always to be 18mm.. As for the 1199 the piston size of the new M50 calipers is 30mm so using a 19mm master will give you a VERY wooden feel and works out a BIG NO NO so the Accossato rep is wrong! The 1199 and M50's works out like so:- The 1199 calipers have a total piston area of 5655 sq. mm and has a master cylinder (16mm!) area of 201 sq. mm. This gives a hydraulic ratio of 5655/201 = 28.1. A 19mm master cylinder has an area of 284 sq. mm. Used with the 1199 calipers you get an hydraulic ratio of 5655/284 = 19.9. I would avoid the 19mm master at all cost unless you like NO feel/wooden and on or off brakes!
Arthur is correct the Panigale uses a 16mm master cylinder and if you use a 19mm it is wooden to a point of unuseable. Ducati part numbers are not that easy......the difference in colours, lever colours etc produce a different number so it may be the same cylinder but the part number will not be the same.
Seems that 848 and 32x32 calipers runs the same master as EVO (M4) 34x34 you would think they would upsize the master to 19mm to maintain the same ratio but no....
Maybe I misheard and he said a smaller size... it was a very brief question if the m/c was for a Panigale and I said no and he continued with something along the lines of "...because of the 34mm pistons they will need a XX bore instead..." or something like that, where XX was a number. It was a very small part of a long conversation during a busy day, and my mind is what HEY LOOK A SQUIRREL!
I have M4's on my stock 848 with the standard 18mm master and to be honest, once I changed the dual carbon pads I mistakenly thought were a good idea, the feel and stopping power was a marked improvement.....but that maybe could just have been the bling factor in my head ;-)
A 19mm master would give more feel, the RCS and M4's is a better option as you can also change the falcrum to give better modulation characteristics. I guess most don't care but a 19 x 20 and 34 x 34 is a good option for the road 19 x 18 for the track.. However most like 19 x 18 road/track. A lot boils down to personal preference. However 19mm on an 1199 and M50's would be unusable.
I have M4 monoblocs on the Monster, combined with a Brembo RCS (19mm with 18mm/20mm fulcrum settings). Originally I tried the 20mm position as I have a similar setup on my 916 - Brembo HPK radial calipers with a Brembo 19/20 radial master cylinder which I find to be spot-on for both feel and power. However I find the M4s have more initial bite (grabbier) than the HPK and so have set the RCS to the 18mm fulcrum rather than the 20 because otherwise it can be too much if I grab the brakes quickly (2 fingers only), part of this maybe due to the lighter weight and softer springs of the Monster but I'm convinced the M4s have more initial grab although no more outright power* than the HPK. * both calipers have more than sufficient for the bike so not necessarily relevant.
