Brakes, check my beer math
 

I have an RC1 SP1 "5/8" (19mm) axial master cyl
What I believe are F4i calipers that have 32/34mm pistons (measured) quality and fresh SS lines, absolutely positively no air in system, using fresh DOT 4.1 fluid and EBC HH pads (bedded in), new EBC rotors.

Currently I have very little lever travel, firm lever, and what I would describe as "wooden" feel with decent stopping power, but not as much as I want or get on other like weight sport bikes I have or ride often.

Goal: More Hyd advantage, more "feel" at lever and some increased lever travel, MC using a remote reservoir (why, because that's what I want, no perceived "performance" advantage

My thought is a radial 19mm MC will do what I want.

The second question is, what bike application to swap from for a radial MC.
I think the Later year ZX6R / ZX14 uses a Nissin radial 19mm MC anything else?
Some (2006? and later?) R6 / R1 used a Brembo 19mm radial MC...I think
If a Brembo 19mm RCS, 19x18? or 19x20?
Thoughts??

You are correct in all of the dimensions for the Honda stuff. Did you know that the stock CBR600F4i uses a 15.87mm master cylinder with those calipers? The VTR1000F also has the same size, with a remote reservoir.

I've just bought a set of F4i brakes and M/C which I plan on fitting to my VFR800 as part of a brake de-link exercise, so will be finding out first hand how that MC/caliper size works out! Seems like a lot of leverage effect will be in play, but maybe there is some lever/pivot geometry magic that reduces that here.

If you want more lever travel/feel, then the smaller diameter MC would be my suggestion. Without going all the way to 15.87mm, the next step down from the 19mm SP1 M/C would be the SP2/CBR954/CBR600RR at 17.46mm.

98-04 VTR uses a 14mm MC with remote res. 2005 VTR uses a, I think, 15.87mm MC with integrated res.

Why don't you just go with an F4i MC as people seem to be very happy with that stock combination when swapping to F4i brakes?

I believe the 19mm MC, axial or radial, gives you too small a leverage ratio and, thus, the wooden feel.

Oh, forgot, you want a remote res...

Do you get a stepped feel when you pull the lever?
The wooden feel may also be caused by another small but usually overlooked problem.
Check the point of contact between the lever and the master cylinder metal boot, they tend to be indented with time and cause the lever not to glide over it, you can use a bit of fine sand paper on both the lever and the boot and apply grease, it works like magic.

If I was staying with an axial MC, and 18mm would be the right direction for sure.. But with a radial, my understanding is 19X18 radial is about the same as an 18 mm axial.

You may well be right about the radial 19mm giving similar braking power to the axial 18mm M/C. There could be some difference in the mechanical leverage effect at the lever between the two arrangements that would cause that.

However, the distance that the M/C piston has to move to pressurise the system and move the pads into disc contact will be the same whether you are talking about a radial or axial m/c, so I'm not sure you would get more "feel" at the lever.

There is an interesting post on the UK Firestorm forum that you might like to read.

www.vtr1000.org ? View topic - Brake Caliper Upgrade

Thanks
Yes I have read that one, and many others.

Ideally I'd like to try a radial 18x18 and 19x18 and see which i like better..
I have now a 19mm axial (RC51) is not the answer, and a 14mm axial (VTR) is not the answer.

After much teeth gnashing, hand wringing and general indecision... I decided :D

Nissin 18mm Radial sourced from a 2014 Daytona 675R to replace my RC-51 Nissin 3/4 axial

New levers all around and a full rebuild of the clutch MC sold do the trick.

Need to figure out the banjo bolt size as I will be using a banjo bolt brake switch vice the OEM micro switch. What I have now might work, or not...just need to see.

How does the 675r get signal to the brake lights?

James

I have the same f4i calipers and tried and sp1 master cylinder and felt it was wooden as well so I stepped down to the SP2 master cylinder and have been happy with it so I concur you need to go down in size with the master cylinder but I'm not sure how a radial master cylinder ratio equates to an axial

So you've gone with the triumph but I also don't know about the banjo bolt sizes you may need to get a custom hose

Standard micro switch....
and it might work, but not counting on it as the micro switch on the MC I have now had to be removed for clearance to get the lever in the position I wanted

I'm dropping a full 1 mm, so that's the right direction.
It's been said a radial is like going down a full "step" vs axial, so that would make this "feel" like a 17mm
the SP2 is 17.5mm .. so I THINK either way this will be better, and not worse.

I have custom lines now, but pretty sure the banjo is the same dia (10mm) I have a customers street triple R in the shop now so........ I was able to get that much. Just not sure of pitch yet... No rush, I'll wait till I get the new MC

Does the SP2 master offer better clearance than the 675R radial?

I understand the cool factor of having a radial though...

James

It is essentially identical to the VTR OEM MC albeit with a larger bore and slightly different leverage ratio. See photo, which has a Mad Hornet adjustable length & flip-up lever with adjustable reach nub and a wind slot (though that is hard to see due to the ProGrip lever skin); clutch side shown for reference. Handle bar "clip-ons" are Dan Moto 3Ds but the SP2 MC works with VTR OEM bars as well as Helibars and Tommaselli 3-way bars (similar to the Dan Motos but with less rise), as I've run them all.

Other way around.. Nissin radial will fit better then the Nissin Axial RC-51 SP1 MC I have now.
Add in the better feel I'm looking for and it is a win / win.

Just saw this one....

don't forget that the piston size is not the sole factor to consider, that the fulcrum length is as well. While I have never seen this measurement listed on axial masters, it is the second numerical (ie. BB) expression in the typical "AA x BB" radial MC spec. To my knowledge, Nissin makes 2 OEM radial MCs, one is 17.5 x 18, the other is 19 x 18. I have used the 19 in the past with same calipers and the set-up works well. However, the 17.5 will give more power and better feel (albeit at the cost of additional lever travel). Having tried numerous set-ups over the years, I would personally recommend an OEM Ducati Brembo (which is 18 x 19; from most any late model Ducati, expect Panigales) or the Nissin 17.5 were I in your situation.

Good luck

I have both the Nissin radial 18 (sometimes referred to as a 17.5) and the Brembo 18mm, both from Daytona 675 and 675R

I have a lever on the way for the 18mm Brembo so will start with that one first.

methinks you'll be a happy customer :)

foiled again
 

Went to install the new Brembo MC today and realized Im still missing a part.
Nissin uses a M10x1.25 banjo, Brembo uses 10x1.0 :rolleyes:

Dumb... I knew that just did not remember.
So new double port M10x1.0 brake switch banjo bolt on order..... and now we wait.