Galespeed Japan Forged Brake Master Cylinder 17 x 17 Ratio RM Series | eBay

Should work well with my existing set-up (Daytona 675 Nissin monoblock calipers, Zcoo pads, Braketech Axis Cobra 298mm rotors, braided lines). Will give me a bit more mechanical advantage (and likely smoother action) than the OEM Ducati cast Brembo 18 x 19 I have on now......

I am also working on another brake-related surprise which will likely materialise in the next day or so.....

 

Beautiful!
Would the 17x17 ratio be about right for 954 or rc51 calipers? The stock MC was 17.xx mm. on those bikes.

 

Yes it would (the 954/SP-2 calipers using 32/30mm piston combo; my 675 calipers are 32/32). One must remember that piston diameter is but one variable to consider when choosing an MC, the other being fulcrum length, that is, the distance from the pivot to the point where the force is applied to the piston. When it comes to radials, the generally accepted nomenclature is XX x YY, where XX is the piston diameter and YY is the fulcrum length. The larger either number is, the more fluid it will push for any lever travel distance. However, all other things beign equal, it will also require more force (felt as a stiffer lever). Be aware, too, that many seem to confuse a stiff lever with additional braking force (when in fact the opposite is true)......

 

well i dont know what this means, "XX x YY" haha but i do know my Magura radial MC, with a piston diameter of 20mm vastly improved braking feel and very much so shrunk my stopping distance.

what is the other number in the 17x17?

 

read the post again, it`s spelled out quite clearly.......

 

okay so that makes mine a 20x20. 20mm piston and 20mm from center of pivot to center of where lever pushes on piston.

now what im havng trouble understanding is how that relates to calipers? for exampler i have SP1 or SP2 calipers but i beleive they are the same so either way 32/30. so is this a good lever ratio per my calipers?

i still dont understand the concept of this since the last thread it was talked about. what it seems like your saying is smaller numbers in the XX x YY ratio, make for better braking?

another issue i have is that the piston on the stock setup is MUCH smaller. seems to me maybe it was around 12mm piston? and the lever felt so much stiffer. now mine feels smooth not "stiff". lots more braking force per pressure applied...

 

OEM MC is 14mm piston (have no clue what the fulcrum mesaurement is, however). At teh MC piston end of things, teh smaller the piston, the higher the line pressure it générâtes (for equal force applied at lever). At the other end, the caliper pistons act as multipliers, and so the larger the pistons the more pressure they will generate. problems arise when the volume of brake fluid displaced is insufficnet to activate the caliper pistons (ie. used up all yoru lever travel and still no braking). AS in most things in life, tehre are no free rides, and braking system compionents are selected to strike the ideal compromise between lever travel and braking force. You can`t optimize both at the same time (against the laws of physics).

Back to my earlier point, many seem to gravitate towards larger MC (with either larger pistons or longer fulcrum lengths, or both) as it inevitably produces a stiffer lever. However, contrary to popular belief, this generates LESS stopping power (less line pressure, so less squeeze). At the other extreme, a small piston or short fulcrum measurement results in a light lever and higher line pressure, but if it rquires you to use up 90% of your lever travel just to get the brakes to engage, you are left with very little margin of safety.....

None of this is magic, it`s all physics and proves, yet again, that one cannot always go by what you feel (in this case effort required at lever)......

 

hmm. im not really going by feel at the lever as much as stopping distance per equal pressure applied. obviously i cant argue with the laws of physics BUT at the track, the new lever VASTLY and i really mean GREATLY improved braking in terms of stopping distance and how much pressure was needed to achieve ample braking. i was able to brake later, and stop sooner, without having to really grb the lever to get the bike to stop. it was very obvious compared to the previous time at the same track with the stock unit.

so im perplexed. what your saying is my setup of 20 x 20 is providing less line pressure but does so with less lever movement. so im really having to squeeze harder, just not as far? that doesnt seem right. at the track with the stocker i had to get 3 or 4 fingers on the lever to come to a stop at some points. with the new MC its 1 finger breaking the whole time...

 

Don`t forget that the execution is just as important as the physics. One of the rasons for going to radial MCs is that they are more rigid, and therefore more efficient (and effective) at converting mechanical force into hydraulic pressure. Any flex in the mechanism is wasted effort......

 

I'd like to bring up this point about usable braking power and confidence.

A smaller MC piston( all else being equal) gives more line pressure and braking power like mikstr said. But you don't get a stiffer lever feel. A stiffer lever( within reason) can give the rider more feedback which in turn allows( gives confidence to) the rider to use more of the available braking force. So, jscobey, with the larger master you have now is most likely improving your confidence on front brakes and making it easier to feel it and thereby you are able to safely apply the brakes harder.

The other part of the equation( already mentioned by mikstr) is the mechanical advantage due to lever fulcrum.

 

okay here is where you are loosing me. the smaller pistons you say create more line pressure...

but if they inner diameter of the brake lines is the same, wouldnt a bigger piston (with more surface area to move brake fluid) push more fluid into those same lines creating more pressure?

 

Another potential downside to a softer lever is that in a panic situation, if one "grabs a handful of brake", you are more likely to exert too much pressure (due to increased mechanical advantage) and possibly lock up the front wheel...... Once again, it`s all about getting what feels best for you...... I like a softer lever, some do not.....

 

a bigger piston moves more fluid, but builds less pressure doing so

 

Yikes, $380! Are you made of money like that Geico commercial rider?

Is it better than a comparable Brembo performance and price wise?

I'm running the old CBR600F4i calipers and SP2 MC, which is a bit better than the SP1 MC. Still have EBC HH+ pads though.

 

no, not made of money, but I don't swill beer like most, nor smoke, or engage in other wasteful and equally asinine activities, so I have to spend my disposable somewhere....

as for it being better or worse than Brembo, I couldn't tell you. Besides, Brembo doesn't offer a radial MC in the size I was seeking, so there was no sense in even exploring that route.... no problem getting 19x18 or 19x20 from them, but that is opposite of the direction I am seeking...... so Galespeed it is........

 

I was joking with the money crack...

I understand your MC sizing and was not sure if Brembo had a 17mm MC. I'm sure you know their RCS19 permits switching between a 18 & 20mm fulcrum length; I wish they made it in a 17mm bore. It comes with a folding lever but not their "low drag" (only available in the "shorty" lever) that even my inexpensive Mad Hornet folding/length adjustable levers have.

https://www.superhawkforum.com/forum...-levers-31588/

Brembo RCS19 Mastercylinder, RCS 19, Brembo RCS 19 MasterCylinder, RCS16 FREE EXPRESS SHIPPING

My

 

I would have gladly bought an RCS17 if they made one but as you stated, they don`t. The Galespeed unit can be upgraded to an RCS-like function by simply changing the lever, so if doesn`t feel quite right, I can replace the lever and fine-tune it. Besides, the seller, Simon, I have bought from before and is a real stand-up guy, so I have faith in his opinion.

I realise it`s not cheap, but the other possible option would have been a Brembo 19x16, and it costs over $700! Here is another fine example, why don`t Brembo offer this unit in forged construction (like they do the 19x18 and 19x20) instead of billet only? BTW, Galespeed make a unit with a 19mm piston that you allows you to adjust the fulcrum between 18 and 16mm, another possible option, but 19x18 is definitely not what I want, so 17 it was.... With the adjustable lever, my new unit could become a 17 (actually 17.5) x 18-16.

Looking forward to trying it out