twist

I have been reading the modifications and upgrades other VTR pilots are doing to their bikes and I am thinking about the radial MC. My question is: is there any real benefit to changing the MC piston size? I think it works like this, smaller delivers more fluid but has more movement at the lever, a larger piston will make the brake lever stiffer and have less adjustability at the caliper end, grabby? Also, is there any real benifit to changing to a radial MC in the first place? Steel braided lines are part of the improvements being made, of course.

mikstr

There are two factors to consider when selecting a radial master: the piston size and the fulcrum length, the latter determining the amount of mechanical advantage you have. For example, Brembo makes three MCs with 19mm pistons, 19x16, 19x18, 19x20. The first number indicates the piston size (dia. in mm), the scond the fulcrum length (or the distance between the pivot and the point on the lever from which the force is applied). Despite having the same piston size, they will each offer different braking characteristics, namely the 19x16 having lighter action, requiring les effort and offering greater power (more mechanical advantage) at the cost of incrased lever travel. AT the other extreme, the 19x20 will have a short lever travel but the lever will be a lot firmer.

IN the end, the choice must be made based on the size of the pistons in the calipers and the type of braking action you prefer.

Hope this helps.

cheers

Thumper

Myself i would keep radial with radial and vice versa. I upgraded to GSXR1000 calipers and MC. Although it is an improvement it in no way compares to my Brembo OEM setup on my KTM's.

You also have to ask yourself if you are going to long term convert your forks over to upside down setup ( i have not). If so you probably will want to wait and do it all at once with the forks you choose

twist

I like the way things feel as set up. Is there any point to going radial if that's the case?

mikstr

Not sure I'm really the right person to answer that question, lol..........

comedo

I've been using the stock VTR master cylinder (14 mm.) with 954 calipers, braided lines and Vesrah pads. The bike stops well but there's a lot of lever travel, the lever feels soft even when the lines are bled properly and not there's not much feel through the lever in spite of my exquisitely sensitive fingertips. I had tried a CBR600RR conventional m/c but I wanted less effort at the lever. Tweety had mentioned using a radial m/c from a 2004-2007 (?) CBR1000RR so I had to get one from ebay. It should be warm enough to ride the bike in March. I won't know if it's a significant improvement until then.
Thanks to mikstr for explaining the differences between the designations of Brembo m/c's.

mikstr

The designations are not just Brembo but are now standard in the industry. FWIW, from what I have found, Nissin makes two radials. One has a 19mm piston, the other 17.5mm, both with 18mm fulcrum length. I am not certain but I think the 1000RR unit you speak of is the 17.5mm version.

I ran the Nissin 19x18 (from a 2006 ZX-6R) for a while with my 900RR/F4i calipers (with 34/32mm piston combo) and eventually settled on an OEM Ducati Brembo 19x16 for the softer lever it provided.

comedo

The 2004-2007 CBR1000RR m/c piston size is 11/16" or roughly 17.5 mm. The piston sizes in the 954 calipers are 32/30. I'm looking forward to trying it.

mikstr

I think you'll be happy with the results.

cheers

superbeater

I went with 954 calipers with the stock 954 pads (Honda HH), SS lines, '07 CBR600RR radial MC. It was a pain to get them bled after putting in new seals.

I really like the feel and lever travel. I've done one track day with this set up and it feels good coming down from 140. I'm real happy with the set up. Especially when the cost factor is considered. Bear in mind that my skills are far from club racer.

VTRsurfer

With stock brakes and EBC HH pads, my brakes are adequate for the spirited canyon riding I do, but I can see where they would fall way short at track speeds.

But when I get off my wife's 2012 GSX-R750, with Brembo monoblock radial calipers and the OEM radial master cylinder, my front brake feels soft. I'll probably eventually go to stainless steel braided lines for the front of my VTR.

NHSH

That alone will be a big improvement for your stock brakes.

JamieDaugherty

My setup is the same as yours and I experienced the same thing. I bored out my master cylinder to 5/8" (roughly 16mm) and it made a world of difference. I know there are 5/8" cylinders available, but this was actually easier for me.

xeris

This is the combination that I'm considering as I already have 954 calipers and braided lines (not installed yet)
I'm interested in how your set-up will perform. Maybe you could get a really big weed burner and dry off a section of road so you don't have to wait till March to test the brakes.

Tweety

Ok... It seems we are missing a part of the fundamentals here... I'm fairly sure most of you guys know this already, but there are a few new guys throwing around suggestions that seem a little less thought out (in this thread and others)... So let's go through the fundamentals first so we know what we are disussing?

Fundamental rule one, it's all about fluid volume... What you are doing when braking is moving fluid from the M/C to the caliper... Maintaining the caliper size and using a larger M/C will move more fluid, ie a quicker transition from no brakes to fully on brakes... But at the same time, it takes more force at the M/C, regardless of the fulcrum, even though there are significant difference between various M/C sizes here... Ie, upgrading the M/C and keeping the wimpy stock calipers will undoubtedly mean a very digital brake... Ie no squeesing, just going superman at the scenery...

Two, mechanical advantage... Now, figure you have a system with a reasonable fluid balance, ie a matching set from one type of bike, or same sized components from two bikes... Then it's down to mechanical advantage... Like mikstr said, the sizing is shown on the M/C, and you can compare it... Go for the end of the span you like...

One thing to keep in mind here through... Radial M/C's is not the same as an axial in the markings... It means the same, bore x fulcrum, but it doesn't mean it's the same in practice... In a axial M/C the fulcrum is the actual mechanical advantage you have... On a radial, it's actually the disadvantage really... You are pressing directly against the cylinder, without a linkage giving you a higher force per movement... That's why radial M/C's are typicaly said to be good for "feel"... You have a very direct impact on the caliper movements... The downside, is that for the same movement, and volume of fluid, it takes more force... Period, not debatable, that's a fact... But that's why a radial caliper is dimensioned a bit different vs the caliper size on most bikes that have them as stock... Basically, they are one "size" down in most cases... You can in most cases equate the CBR100RR's 17 mm M/C to most radial 19 mm's...

Three... Balance, balance, balance... Oh... I forgot... Balance... Going bigger in one end is almost never a bright idea... Changing to a radial M/C is fine (if you account for it) or swapping/mixing/matching brands/original model/whatever is also fine... As long as you stay within reasonable changes...

For fundamental 4-9 see three...

So, ten... If you have OEM lines or braided lines isn't really much difference as long as they are fresh... Ten year old OEM lines aren't bad because they are OEM, but since they have begun breaking down a couple of years ago... Still a really worth while upgrade, and should really be the first one...

chemomche

Yep, completely argee with you

I found it when trying to upgrade my ktm sumo bike front brake.
Bigger master seemed good idea, but when i put 14mm axial master witn a two pot caliper.....well, the idea was no good - wooden lever, no braking at all.
11mm axial with 4 pot.....lever goes to the end, no braking

4 pot brembo with 17,5 nissin radial - pretty good but still little wooden
then get 16mm brembo radial from r6 and the things are little better
may not be best but good enough for me

For the Hawk
I bought it with 6 pot tokicos, but OEM MC - sponge lever, braking pretty scary because i got no feel. Installed 19mm nissin, new pads(ferodo sinterGrip HH), lines, fluid, cleaned the calipers and now the bike brakes really well.

So keep your brakes fresh and make them balanced.

Stephan

Stock m/c and calipers means very digital brake, bigger m/c from F4i (or similar 16 mm) will improve the braking. If I consider cheaper and easier way how to improve brakes, I would go this way, it´s tested.

Tweety

Uh... Nope... I tested that a very, very long time ago... I found it made the bike more prone to locking up the front wheel... Not a good setup at all IMHO... A bit better stopping power than stock, but just as digital, if not more... The problem is that the stock calipers require so little fluid volume for full movement that they are rather useless really...

So not really a worthwhile upgrade... You get much better results spending the few dollars more that it takes to get a complete setup from an F4i or similar...

Stephan

Ok, different rider, different experiences, different opinion. I would´t say stock brakes are so bad until I tried CBR954 brakes :-)

mikstr

Curiously, the Sumitomo monoblock brakes used on numerous Yamahas (incl. R1s and R6s) used the very same piston sizes as the VTR (27/30mm) and, in some instances, the same size MC (14mm; though later versions used a Brembo radial 16X18) and these bikes always received praise for their brakes. Can`t help but wonder what they did right and Honda got wrong with the VTR.....

Hawkrider

I am running a 1000RR front end (with calipers and rotors, of course) and stayed with the stock master cylinder. I think I tried the 929/RC51 master and, along with not fitting great, found a wooden feel. Lever feel and travel were rock solid, but in actual riding I didn't have the "feel". Went back to stock master and although the lever travel is slightly higher, the feel is back along with braking confidence.

twist

from what you've said, I believe that keeping the MC and addressing the calipers and brake lines is my best course. I'm probably not as fast as you; the stock set up is good for me but could be a little better. Steel lines and pads should do the trick for me. The front end is another story though.

NHSH

+1 I have the exact same setup and I like it better as well, I tried at first using the CBR1000RR MC, but got that wooden feel you mentioned. I rebuild the CBR MC thinking that the seals are just too old or dry, but never actually used it again after installing the VTR stock MC, it just works great!

Tweety

Actually, that makes a great deal of sense... The 929 and RC51(SP1) uses a 19 mm axial master with a comparatively short mechanical advantage, which is rather oversize for the 1000RR's calipers, hence the wooden feel...

I believe you'd be rather pleased with the feeling of the smaller 17 mm master from the 954 or RC51 (SP2) or the "matching" 17 mm radial one from the 1000RR... It takes a little fiddling to get it not to hit the fairing, but I got mine in there... And it's just as sensitive as the one you are running now, but should have just slightly less travel... Should also have a notable increase in outright stopping power, should you ever need to really clamp down...

NHSH

I guess it's time to try my rebuild 1000RR MC

8541Hawk

I'm running a complete SP2 brake system and really like it (along with the 320mm rotors which also really improve the braking)

I still have a radial master to mount yo but need to replace my clip-ons first....

VTRsurfer

What pads are you running up front? I switched over to EBC HH pads even before the OEM pads wore out. I noticed a big difference in initial bite. I'm about to put my 3rd set on.

And I even locked up the front tire once, when a woman in an SUV cut me off, then slammed on her brakes to grab a parking spot.