919 F4i calipers re Radial Master Cylinder - Wrist Twisters
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post #1 of 66 Old 10-16-2010, 01:42 PM Thread Starter
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919 F4i calipers re Radial Master Cylinder

Winter projects are being sketched in.
I've decided what to do next with my front brakes.
I'm going to put on F4i calipers a used Honda or Suzuki or ? OEM radial master cylinder that has a built in brake light switch.
Has anyone out there done it before ?
If so, what master piston size did you use?
Once I get the calipers, I'll measure the pistons, do the slave/master surface area ratio calculations and select a master cylinder piston size that yields low 30s (i.e. 32:1 etc).
Ahead of that, if anyone knows the F4i caliper piston sizes, I'd appreciate hearing what they are, as well as any comments from anyone who has already gone the radial master / F4i caliper route.
I already have the EBC rotors on the bike, and the braided SS lines ready to go on. Present pads are EBC HH and I plan to go EBC Extreme Pro for the F4i calipers.

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post #2 of 66 Old 10-16-2010, 03:19 PM
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if the F4i disks are the same size diameter as the 919, i would stick with a ratio very close to that of the stock F4i caliper and master cylinder piston diameters.

Also, i have found the OEM NISSIN pads to be the best, its the only thing ill ever run on the front of my hondas.

That being said, pm LDH pretty sure he knows lots bout those piston sizes.... or it might of been rob.

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post #3 of 66 Old 10-16-2010, 03:33 PM
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.....curious why you'd go the f4i route.....instead of the RC51/RC master cylinder route? Have any good insight on the f4i stuff?

Currently drooling over an RC51 brembo/radial MC setup on eBay BTW......

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post #4 of 66 Old 10-16-2010, 03:58 PM
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......sorry, just went digging.....man, there's alot of info here on the f4i caliper swap......

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post #5 of 66 Old 10-16-2010, 04:00 PM
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the f4 master is a 16 mm, but is not radial. I have a f4 track bike and the brakes are considerably better than the 919.
the cbr929/54 is 18 mm.
i wished to do this but am still trying to track down a 16mm master that can accept the mirror. There are aftermarket ones on ebay but they are an unknown quanity for me.
I am looking at the early fz1 at the moment

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post #6 of 66 Old 10-16-2010, 04:01 PM
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i am thinking the the calipers on the cbr600rr up until 2003 will also fit.

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post #7 of 66 Old 10-16-2010, 04:40 PM Thread Starter
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Quote:
Originally Posted by arctic954 View Post
.....curious why you'd go the f4i route.....instead of the RC51/RC master cylinder route? Have any good insight on the f4i stuff?

Currently drooling over an RC51 brembo/radial MC setup on eBay BTW......
Very good question.
I was toying with doing a 954 front brake graft, I love big rotors. But seeing as I have the 07 750 GSX-R750 as a dedicated Track Day bike, I realize going that radical on the 919 doesn't make much sense. The F4i has the same rotor diameter as the 919, as in 296 mm. (The 954s are 330, 929s are 310s and RCs are 320s). The F4i calipers have about a 13 % greater pad area than the 919 calipers offer. ( I got the pad drawings from EBC and compared them) So I'll get some added pad area, and the radial master is supposed to do something for me, right ? Easy bolt on that won't cost too much and I'll have the bike forever. I'll probably go with the EBC Extreme Pro pads.

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post #8 of 66 Old 10-16-2010, 04:48 PM Thread Starter
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Originally Posted by davehirt View Post
the f4 master is a 16 mm, but is not radial. I have a f4 track bike and the brakes are considerably better than the 919.
the cbr929/54 is 18 mm.
i wished to do this but am still trying to track down a 16mm master that can accept the mirror. There are aftermarket ones on ebay but they are an unknown quanity for me.
I am looking at the early fz1 at the moment
F4 pads are the same as F4i, so the calipers are common in that respect. Unknown is the piston layout. But at least I now know that the F4 used a 16 mm master piston diameter so big thanks for that.

I'm using bar end mirrors.
This also let my switch to a F4i clutch lever assembly which uses the same lever as a 919 but has the pivot pin closer to the handlebar.
There are bar clamp type mirror mounts you can buy, try Zeigler or others.

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post #9 of 66 Old 10-16-2010, 05:11 PM Thread Starter
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I'm also going to check out the ratios that our 600 and 750 GSX-Rs use. I'll measure the pistons, do the calcs, and compare to the pre 08 19.05 mm MC piston to the later 17 mm MC piston diameter. Locally, a common track related change on 08s and later, is to go back to the earlier 19.05 mm MC, apparently the 17 mm MCs felt too mushy for a number of folk. Anyway, all those calcs should yield interesting results re any change in ratio logic as a function of the use of conventional or radial MCs. I've never seen an explanation about why radials are better or what make them different. My present thinking is that ratio is ratio is ratio so, low 30s should be good for radials if it is good for conventionals.

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post #10 of 66 Old 10-16-2010, 06:39 PM
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Quote:
Originally Posted by mcromo44 View Post
I'm also going to check out the ratios that our 600 and 750 GSX-Rs use. I'll measure the pistons, do the calcs, and compare to the pre 08 19.05 mm MC piston to the later 17 mm MC piston diameter. Locally, a common track related change on 08s and later, is to go back to the earlier 19.05 mm MC, apparently the 17 mm MCs felt too mushy for a number of folk. Anyway, all those calcs should yield interesting results re any change in ratio logic as a function of the use of conventional or radial MCs. I've never seen an explanation about why radials are better or what make them different. My present thinking is that ratio is ratio is ratio so, low 30s should be good for radials if it is good for conventionals.
technically yes.... the only things that really matter are piston size ratio, pad area, disk diameter, and lever ratio (mechanical advantage the lever has on the master cylinder piston)

you could get a very touchy setup by going with too small of a master (ie using the stock 919 master with breaks with bigger pistons)

or you could get a not so good setup if you went with a radial master (which tend to have larger pistons) and the stock 919 calipers.

The best thing to do is keep mc and caliper piston size nearly the same as their original application, very slightly for different disk diameters.

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post #11 of 66 Old 10-16-2010, 07:24 PM Thread Starter
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Quote:
Originally Posted by nd4spdbh View Post
technically yes.... the only things that really matter are piston size ratio, pad area, disk diameter, and lever ratio (mechanical advantage the lever has on the master cylinder piston)

you could get a very touchy setup by going with too small of a master (ie using the stock 919 master with breaks with bigger pistons)

or you could get a not so good setup if you went with a radial master (which tend to have larger pistons) and the stock 919 calipers.

The best thing to do is keep mc and caliper piston size nearly the same as their original application, very slightly for different disk diameters.
I found some decent info on the Optimum Performance Products Inc. (OPP Racing) - Performance Motorcycle Parts Distributor site. There is a bit of a tutorial on Radial MCs. I'll be checking my 750's caliper pistons and MC "Interaxis Distance" then relate all that to the pistons in the F4i calipers then select a Radial MC piston diameter and Interaxis Distance for used OEM items.

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post #12 of 66 Old 10-16-2010, 08:36 PM
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.....can't wait to see what radial MC/f4i caliper combo you come up with....

were all going to benefit from this info.

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post #13 of 66 Old 10-16-2010, 11:33 PM
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i am sure the f4 and f4i are both 16 mm, just did not make my post clear.
I wish to use a standard master, not radial as i like the cleaner look, this does not leave me much room for a bar clamp mirror.
The brakes are good already on the 919 so an f4 upgrade will be sufficient for me.
Going radial or too a 954 setup is a bit of overkill in my situation.
But the calipers (even lger pistons) and 18mm radial piston set up are a straight swap i believe

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post #14 of 66 Old 10-17-2010, 04:21 AM
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i am thinking the the calipers on the cbr600rr up until 2003 will also fit.
There was no 600RR before 2003.

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post #15 of 66 Old 10-17-2010, 07:03 AM
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Correct me if im wrong......

From reading other posts.....it is my understanding that f4i, 929, 954, and RC51 calipers all bolt right up to 919/f4i forks....with each having different piston sizes & a matching Honda MC. To accomadate different sized rotors, each caliper uses a different bracket per the model. If you want to use rotors from another bike, all you need also is it's adapter bracket.

Is this info way off?

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post #16 of 66 Old 10-17-2010, 09:35 AM Thread Starter
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Correct me if im wrong......

From reading other posts.....it is my understanding that f4i, 929, 954, and RC51 calipers all bolt right up to 919/f4i forks....with each having different piston sizes & a matching Honda MC. To accomadate different sized rotors, each caliper uses a different bracket per the model. If you want to use rotors from another bike, all you need also is it's adapter bracket.

Is this info way off?
Yes but not quite.
1
My understanding is that all the calipers you listed will indeed mount to 919 or F41 fork legs, and properly position the caliper for use with 296 mm diameter rotors that the 919 and F4i both use. There is a range of caliper piston sizes throughout, so proper master cylinder piston diameter selection is crucial.
2
I believe the only bike that used "adaptor brackets" between the fork mount and the caliper mount was the RC51. I think that those "adaptor brackets will mount to 919 or F4i fork legs, and position the caliper radially to the axle in terms of a 320 mm rotor, and not the 296 mm rotor of a 919 or F4i.
3
While mounting the range of calipers to the 919 or F4i fork legs is a slam dunk, what isn't is if you try to use the associated rotors. See 2 above re the RC51. As for the 929, it used 310s while the 954s used 330s. If those rotors are on a 919, the calipers will not be in the right position, and some fairly serious adapting work will be needed. My guess is that it would actually be easier to adapt the 954 stuff as the caliper needs to be further away from the standard leg mounts than the 929 would, there being more radial room to work with, so to speak. (296/2 as compared to 330/2 as in 17 mm of radial offset being needed)
4
Back to the range of calipers that we all seem to accept that can be fitted up to 919 or F4i legs for use with 919 and F4i 296 mm rotors.
See the attached series of Brake Pad Drawings. VERY interesting. One can easily see the difference between the 919 and F4i pads. (see FA187 and FA296)They are both "arched" for 296 mm OD rotors. Now look at the FA265 for the 929, 954 and RC51. The pad is nominally dimensioned the same as the FA296 for the F4i BUT the the FA265 will have its pad face "arched" for larger rotors than the 919 and F4i use. Personally, I would want pads I know were "arched" for the rotor diameter I was using. Something else comes out of these drawings. They suggest to me that F4i pads will mount into 929 or 954 calipers. So now we all have yet more to check out and figure out.


Attached Images
File Type: jpg 919 front brake pad.jpg (205.5 KB, 14 views)
File Type: jpg F4i front brake pad.jpg (167.5 KB, 16 views)
File Type: jpg 900 929 954 rc52 front brake pad.jpg (182.8 KB, 11 views)

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post #17 of 66 Old 10-17-2010, 10:46 AM Thread Starter
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Quote:
Originally Posted by mcromo44 View Post
Yes but not quite.
1
My understanding is that all the calipers you listed will indeed mount to 919 or F41 fork legs, and properly position the caliper for use with 296 mm diameter rotors that the 919 and F4i both use. There is a range of caliper piston sizes throughout, so proper master cylinder piston diameter selection is crucial.
2
I believe the only bike that used "adaptor brackets" between the fork mount and the caliper mount was the RC51. I think that those "adaptor brackets will mount to 919 or F4i fork legs, and position the caliper radially to the axle in terms of a 320 mm rotor, and not the 296 mm rotor of a 919 or F4i.
3
While mounting the range of calipers to the 919 or F4i fork legs is a slam dunk, what isn't is if you try to use the associated rotors. See 2 above re the RC51. As for the 929, it used 310s while the 954s used 330s. If those rotors are on a 919, the calipers will not be in the right position, and some fairly serious adapting work will be needed. My guess is that it would actually be easier to adapt the 954 stuff as the caliper needs to be further away from the standard leg mounts than the 929 would, there being more radial room to work with, so to speak. (296/2 as compared to 330/2 as in 17 mm of radial offset being needed)
4
Back to the range of calipers that we all seem to accept that can be fitted up to 919 or F4i legs for use with 919 and F4i 296 mm rotors.
See the attached series of Brake Pad Drawings. VERY interesting. One can easily see the difference between the 919 and F4i pads. (see FA187 and FA296)They are both "arched" for 296 mm OD rotors. Now look at the FA265 for the 929, 954 and RC51. The pad is nominally dimensioned the same as the FA296 for the F4i BUT the the FA265 will have its pad face "arched" for larger rotors than the 919 and F4i use. Personally, I would want pads I know were "arched" for the rotor diameter I was using. Something else comes out of these drawings. They suggest to me that F4i pads will mount into 929 or 954 calipers. So now we all have yet more to check out and figure out.


I missed a not so subtle detail and just caught it now.
This said in terms of possibly using F4i pads in 929/954/rc51 calipers that is.
See the pad drawings already posted.
Keep the following in mind.
The EBC data shows a 8 mm pad thickness for the 919 and a 7.6 for the F4i.
Both use a perforated stainless steel shim. I don't know if the EBC data thicknesses include the shim or not. (My EBC HH fronts for the 919 came with shims on, the rear didn't - so I reused the OEM part there.)
The EBC data shows a 8.3 mm pad thickness for the 929/954/rc51 AND a caution not to use the OEM shim, which tells me the EBCs not only don't come with shims ala the OEMs, but for some reason, or not to be used. Maybe the pad backing/mounting plate is thicker. So in terms of the possible use of F4i pads in 929 etc calipers, keep in mind that the F4i items are for sure thinner overall, than the 929 etc items.

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post #18 of 66 Old 10-17-2010, 02:28 PM
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From the research I have been doing on the various Nissin calipers fitted to Hondas, the spacing of the mounts and their relative position to an arbitrary datum (the midpoint of a line drawn from the center of the trailing piston to the center of the leading piston) is the same to the limits of my PME. This implies the mounts on the fork legs are positioned to properly place the calipers on whatever diameter rotors are fitted. From this, it also folllows that if you are fitting RC51 calipers to the 919 they will bolt right on and place the pads close to perfectly on the smaller rotors. At least the 929 calipers I got from EBAY dropped right onto the 919 forks and the pads were right where they needed to be, made more significant by the fact that the 929 has 330mm rotors.

There is a problem with the dimensions posted by mcromo44 -- checking with dimensions taken directly from 919 & 929 pads that I have here the width is right but the height is way off. I can only conclude the dimension they give is from the center of the retention hole to the lower edge of the pad, not the total friction material height. Since the width of the friction surface of the 919 rotor is 32.3mm and the height of the pad is 32mm, it would seem this is a more accurate way to do things. BTW, the height of a 929 pad is also 32mm. See the first illustration for a comparison.

As you can see from the revised dimensions the 929 pads have roughly 9% greater area per pad, a total of 36% larger friction area total.

Something else I found recently is the radial calipers fitted to a 2009 CBR1000rr has exactly the same piston diameters as the '94 CBR 900 calipers I had a while back: 32 / 30. A bit surprising.
Master cylinders.
Let's look at a breakdown of master cylinders, radial and otherwise. Here's an article on the Brembo radials:
Overview of a Brembo Master Cylinders
As you can see the lever is quite straightforward -- essentially a straight run from your fingers to the piston. Cleaner actuation? Not by virtue of what I've said so far. Let's take a look at both types and work it out.

First, a conventional master:
The brake lever pivots at the master cylinder body which transfers motion through a right angle to the actuation point at the piston. The average mechanical ratio is about 3 to 3.5 to 1. The disadvantage to this setup is the angle from the centerline of the piston to the mean center of the lever pivot changes substantially from it's at rest position to the point where the brakes apply, an average of 4 to 5.5 degrees. In order to accomodate this change the actuation arm scans across the face if the piston, creating a thrust load on the piston until the angle is 90 degrees, and ideal point where the brakes should apply. The end result of this is the piston binds very slightly in its bore, using up a small percentage of the force you are applying. It gets considerably worse when the lubrication between the arm and the end of the piston breaks down, where the binding force gets high enough to practically freeze up the lever action and wear the bore and seals badly. Not one little bit of good!

On to the Brembo 19RCS:
The radial master is different in that it uses a larger piston size, in this case 19mm, and changes the mechanical ratio by a couple of methods. First, the actuation arm length is 18 or 20mm, about 38% to 25% shorter than an average conventional master. Additionally, the distance from the pivot to the point where your fingers contact the lever is greater. Why? The pivot on the conventional is forward of the handlebar mount by an average of 19mm, while the radial pivot is behind the mount by roughly 15mm, making a total difference of 34mm. Add that to the length of the conventional lever and you have a mechanical ratio of between 6:1 and 5.4:1. Another advantage is the angle change is considerably less -- about 1.5 degrees versus 4.5 degrees. This results in less binding and a smoother feel. Of course the fact that the Brembo is a high end unit means more attention is being paid to surface finish of the bore, teflon lipped seals may be used, and the lever and pushrod pivots are of a higher quality. The result is a smoother feel under pressure and cleaner actuation. This is what retailers are talking about when they say it works better, but they invariably attribute it to the position of the lever and piston. The truth is I can and have built conventional master cylinders that were every bit as smooth as a radial by adopting the same methods Brembo uses, but it wouldn't sell simply because it isn't a radial!

Let's break it down. Take a system with two calipers with 4 pistons of 32/30 mm each and a conventional master of 17mm. The hydraulic ratio is 26.63:1, and when multiplied by the mechanical ratio becomes 93.2:1. Fine and dandy. The 19mm radial master has a hyd. ratio of 21.32:1, and multiplying by the mechanical ratio gives a total ratio of 127.9:1 to 115.1:1. The end reslut is the brakes will be more sensitive, but due to the better quality components and attention to detail the feel should still be good.

Rob
Attached Images
File Type: jpg Brake pad fitting.jpg (25.8 KB, 6 views)
File Type: jpg Conventional_radial_ master_ cylinder_ comparison.jpg (53.6 KB, 16 views)

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post #19 of 66 Old 10-17-2010, 03:02 PM
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Thats interesting to note the f4i, cbr600rr, 929 and 954 pads are as near as dam it all the same size! I used cbr600rr calipers on my standard forks and i noted that one of the pistons in the calipers were 5mm bigger than the stock 919 items.
Are the 929 and 954 pistons the same size as the cbr600rr?
Also if you think we could use the 320mm 954 discs and the rc51 caliper adapters that would be great if it works...........I remember LDH saying he had an alignment issue when he tried the calipers, did he try the discs too?

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post #20 of 66 Old 10-17-2010, 03:05 PM Thread Starter
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Rob,

Thanks for the very authoritative and expansive reply, as usual. Hat's off to you, Sir. I'm most intrigued by the 30/32 piston sizing you found as common for 900RR and late model CBR1000RR. It'll be interesting to see what the size in the F4i is/are. By chance, do you know what the master piston diameter is for the aforementioned 1000RR ?
Again,thanks for chiming in.

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post #21 of 66 Old 10-17-2010, 03:17 PM Thread Starter
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Quote:
Originally Posted by robtharalson View Post
From the research I have been doing on the various Nissin calipers fitted to Hondas, the spacing of the mounts and their relative position to an arbitrary datum (the midpoint of a line drawn from the center of the trailing piston to the center of the leading piston) is the same to the limits of my PME. This implies the mounts on the fork legs are positioned to properly place the calipers on whatever diameter rotors are fitted. From this, it also folllows that if you are fitting RC51 calipers to the 919 they will bolt right on and place the pads close to perfectly on the smaller rotors. At least the 929 calipers I got from EBAY dropped right onto the 919 forks and the pads were right where they needed to be, made more significant by the fact that the 929 has 330mm rotors.

There is a problem with the dimensions posted by mcromo44 -- checking with dimensions taken directly from 919 & 929 pads that I have here the width is right but the height is way off. I can only conclude the dimension they give is from the center of the retention hole to the lower edge of the pad, not the total friction material height. Since the width of the friction surface of the 919 rotor is 32.3mm and the height of the pad is 32mm, it would seem this is a more accurate way to do things. BTW, the height of a 929 pad is also 32mm. See the first illustration for a comparison.

As you can see from the revised dimensions the 929 pads have roughly 9% greater area per pad, a total of 36% larger friction area total.

Something else I found recently is the radial calipers fitted to a 2009 CBR1000rr has exactly the same piston diameters as the '94 CBR 900 calipers I had a while back: 32 / 30. A bit surprising.
Master cylinders.
Let's look at a breakdown of master cylinders, radial and otherwise. Here's an article on the Brembo radials:
Overview of a Brembo Master Cylinders
As you can see the lever is quite straightforward -- essentially a straight run from your fingers to the piston. Cleaner actuation? Not by virtue of what I've said so far. Let's take a look at both types and work it out.

First, a conventional master:
The brake lever pivots at the master cylinder body which transfers motion through a right angle to the actuation point at the piston. The average mechanical ratio is about 3 to 3.5 to 1. The disadvantage to this setup is the angle from the centerline of the piston to the mean center of the lever pivot changes substantially from it's at rest position to the point where the brakes apply, an average of 4 to 5.5 degrees. In order to accomodate this change the actuation arm scans across the face if the piston, creating a thrust load on the piston until the angle is 90 degrees, and ideal point where the brakes should apply. The end result of this is the piston binds very slightly in its bore, using up a small percentage of the force you are applying. It gets considerably worse when the lubrication between the arm and the end of the piston breaks down, where the binding force gets high enough to practically freeze up the lever action and wear the bore and seals badly. Not one little bit of good!

On to the Brembo 19RCS:
The radial master is different in that it uses a larger piston size, in this case 19mm, and changes the mechanical ratio by a couple of methods. First, the actuation arm length is 18 or 20mm, about 38% to 25% shorter than an average conventional master. Additionally, the distance from the pivot to the point where your fingers contact the lever is greater. Why? The pivot on the conventional is forward of the handlebar mount by an average of 19mm, while the radial pivot is behind the mount by roughly 15mm, making a total difference of 34mm. Add that to the length of the conventional lever and you have a mechanical ratio of between 6:1 and 5.4:1. Another advantage is the angle change is considerably less -- about 1.5 degrees versus 4.5 degrees. This results in less binding and a smoother feel. Of course the fact that the Brembo is a high end unit means more attention is being paid to surface finish of the bore, teflon lipped seals may be used, and the lever and pushrod pivots are of a higher quality. The result is a smoother feel under pressure and cleaner actuation. This is what retailers are talking about when they say it works better, but they invariably attribute it to the position of the lever and piston. The truth is I can and have built conventional master cylinders that were every bit as smooth as a radial by adopting the same methods Brembo uses, but it wouldn't sell simply because it isn't a radial!

Let's break it down. Take a system with two calipers with 4 pistons of 32/30 mm each and a conventional master of 17mm. The hydraulic ratio is 26.63:1, and when multiplied by the mechanical ratio becomes 93.2:1. Fine and dandy. The 19mm radial master has a hyd. ratio of 21.32:1, and multiplying by the mechanical ratio gives a total ratio of 127.9:1 to 115.1:1. The end reslut is the brakes will be more sensitive, but due to the better quality components and attention to detail the feel should still be good.

Rob
Rob,

Do you know what the logic is behind the differential caliper piston diameters?
Is this a wedging or distortion related design tactic ?

And thanks for correcting the errors you find in the catalog dimensions I used without enough thought - seeing as I have had the pads in my hand !

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post #22 of 66 Old 10-17-2010, 03:19 PM Thread Starter
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Thats interesting to note the f4i, cbr600rr, 929 and 954 pads are as near as dam it all the same size! I used cbr600rr calipers on my standard forks and i noted that one of the pistons in the calipers were 5mm bigger than the stock 919 items.
Are the 929 and 954 pistons the same size as the cbr600rr?
Also if you think we could use the 320mm 954 discs and the rc51 caliper adapters that would be great if it works...........I remember LDH saying he had an alignment issue when he tried the calipers, did he try the discs too?
Woodyeee, were the cbr600rr caliper pistons common in size or were two diameters used ? I have not measure my 919 caliper pistons, so I'm not sure how to interpret the 5 mm difference you noted above, as in all same size and 5 mm larger, or two sizes and both 5 mm larger.
Please advise.

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post #23 of 66 Old 10-17-2010, 03:35 PM
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I seem to remember that they were 2 differant sizes.....it was around 3 or 4 years ago when i changed them so i may not be correct but one was say 30mm and the other piston was 32mm as opposed to the 919 standard pistons being 30mm and 27mm
I can measure them later if you like................Ive also just looked at the rc51 bracket and it looks like the spacing is a bit bigger than the standard fork spacing?

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post #24 of 66 Old 10-17-2010, 03:36 PM
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Stock 919 caliper pistons are 30.15mm and 27mm, which interestingly enough is 1 3/16" and 1 1/16". Don't know if that's significant or not.
The rationale behind the differentially sized pistons is to compensate for the "cam effect" inherent in all multi piston calipers -- the leading edge of the pads tend to pull in toward the rotor when applied when compared to the rest of the pad, wearing more quickly than the trailing edge. The smaller pistons on the leading side apply less force to the pads and actuate after the trailing pistons, generally evening out the wear.
As to the size of the 1000rr master cylinder ... I think it's 18mm, but don't quote me on that.
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post #25 of 66 Old 10-17-2010, 03:40 PM
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Well it looks like i was a cigarette paper out on the measurement! ...........but its close enough for me, thanks Rob.

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post #26 of 66 Old 10-17-2010, 03:42 PM Thread Starter
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Originally Posted by woodyeee View Post
I seem to remember that they were 2 differant sizes.....it was around 3 or 4 years ago when i changed them so i may not be correct but one was say 30mm and the other piston was 32mm as opposed to the 919 standard pistons being 30mm and 27mm
I can measure them later if you like................Ive also just looked at the rc51 bracket and it looks like the spacing is a bit bigger than the standard fork spacing?
If you are open to taking the time to measure, I, and surely others too, would be most grateful. Thanks for offering !

I'm not at all sure about the RC51 adaptor brackets. If one was contemplating RC51 rotors, for sure an adaptor would be needed to properly position the RC51 calipers on the 919 or F4i legs. But such an adaptor would likely be fairly easy to design and fabricate, if a special really had to be made up.

By the way, how's your engine these days ? Wasn't it you that has some turbo boost related issues not that long ago ?

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post #27 of 66 Old 10-17-2010, 04:10 PM
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I have an issue with the cooling or so it seems, When running at 5 or 6 psi of boost everything is fine.......But when you turn up the boost the temp gets a little too hot...or so i thought! So i went and made a custom radiator and it still did it! What is really happening is on high boost say 8 or 9 psi the coolant is being forced out of the expansion tank before it gets hot! So my next plan of action is to renew the head gasket and torque the head down a few more lbs

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post #28 of 66 Old 10-17-2010, 04:53 PM Thread Starter
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I have an issue with the cooling or so it seems, When running at 5 or 6 psi of boost everything is fine.......But when you turn up the boost the temp gets a little too hot...or so i thought! So i went and made a custom radiator and it still did it! What is really happening is on high boost say 8 or 9 psi the coolant is being forced out of the expansion tank before it gets hot! So my next plan of action is to renew the head gasket and torque the head down a few more lbs
You have had some challenges, that is for sure. You have an ignition retard as well, right ? Anyway, be real careful on the head torquing. You've done yours before, I know that. I see the manual calls of moly di on the 9 mm threads as well as the mating flange surfaces (washer top, underside of bolt head). I'd be real careful. I've only had limited experience with moly di on threads, but my recollection is that the needed torque does not kick up like it does with 5W oil. Maybe it would be better to torque it to spec, then clock the bolts some number of degrees instead, and not rely on a torque wrench ? Also, on the head and deck surfaces I am fiendish about dressing and cleaning them after they have been cleared of all old gasket material. I been using 400 wet paper dry, very lightly in circular patterns. Then cleaning with acetone or lacquer thinner before assembly. By the way, what is the type of head gasket the 919 uses ? Is it one of the elastomer coated metal shim types with crush zones ?

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post #29 of 66 Old 10-17-2010, 09:37 PM
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f4 pistons are 32,34 o.d

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post #30 of 66 Old 10-18-2010, 06:28 AM
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The 2003/4 cbr600rr front caliper piston sizes are 30 and 32mm od.

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post #31 of 66 Old 10-18-2010, 06:38 AM
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You have had some challenges, that is for sure. You have an ignition retard as well, right ? Anyway, be real careful on the head torquing. You've done yours before, I know that. I see the manual calls of moly di on the 9 mm threads as well as the mating flange surfaces (washer top, underside of bolt head). I'd be real careful. I've only had limited experience with moly di on threads, but my recollection is that the needed torque does not kick up like it does with 5W oil. Maybe it would be better to torque it to spec, then clock the bolts some number of degrees instead, and not rely on a torque wrench ? Also, on the head and deck surfaces I am fiendish about dressing and cleaning them after they have been cleared of all old gasket material. I been using 400 wet paper dry, very lightly in circular patterns. Then cleaning with acetone or lacquer thinner before assembly. By the way, what is the type of head gasket the 919 uses ? Is it one of the elastomer coated metal shim types with crush zones ?

Yes ive had a challange or two but i wont let it win me!! Hell i could just run it on low boost and i'm sure it would be fine.......But whats the point of fitting a turbo and not be able to turn it up a little
The head gasket is one of the coated shim types.

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post #32 of 66 Old 10-18-2010, 06:44 AM Thread Starter
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Quote:
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Yes ive had a challange or two but i wont let it win me!! Hell i could just run it on low boost and i'm sure it would be fine.......But whats the point of fitting a turbo and not be able to turn it up a little
The head gasket is one of the coated shim types.
I have no doubt you'll get it sorted out on the higher boosts as well.

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post #33 of 66 Old 10-18-2010, 07:34 AM
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With all this info....... it sure would be sweet to have the F4I calipers ---- and to pick up the correct Brembo RCS Radial Master cylinder to match.

now....the question..... do you think the 296mm brake rotor is up to the task?

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post #34 of 66 Old 10-18-2010, 10:07 AM Thread Starter
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With all this info....... it sure would be sweet to have the F4I calipers ---- and to pick up the correct Brembo RCS Radial Master cylinder to match.

now....the question..... do you think the 296mm brake rotor is up to the task?
Depends on the task. I'm running EBC rotors and HH pads and am outbraking some 600s at the end of a half mile straight. In other words, some 600 track dayers are very spooked by the speeds they reach, the braking power they have, and brake real early and not very hard. For a high speed track with heavy braking, bigger rotors would be nice on the 919, thinking 135 - 140 mph and weight of bike. Necessary ? No. On the road ? No. For Trik Look ? YES !
Being rationale about it, I think the F4i calipers, good pads, good master of overall ratio you want, will be more than adequate and is a reasonable level to go to. Personally, I'm hoping an OEM radial MC with brake switch will be found that has has the piston diameter I figure will work. Once I get the 750 GSX-R caliper pistons measured, that will offer big insight as to sizing to use re the MC.

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post #35 of 66 Old 10-18-2010, 03:32 PM
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Grafting

Has anyone thought about or completed grafting the front of a 954RR, 929RR or a 900RR onto a 919. Better suspension and brakes!!!

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post #36 of 66 Old 10-18-2010, 05:40 PM Thread Starter
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Has anyone thought about or completed grafting the front of a 954RR, 929RR or a 900RR onto a 919. Better suspension and brakes!!!
Yes.
Yes.

RC51 front end swaps seem to be the major one, and they are the best overall dimensional match, ride height in particular.
That swap is well scienced out by the number done so far.

I want to maintain the old school front end look. If that wasn't the case, it would be an RC51 front end going on it.

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post #37 of 66 Old 10-19-2010, 07:04 AM
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which is funny..... you hear LDH saying that stock RC51 suspension needs to be reworked in order to utilize its true potential! Have been adding up the numbers.....I'm thinking it would cost well over $1500+ to do it. Seems that the biggest cost and PIA is figuring out the whole tripple clamp issue.... not to mention figuring out how to mount everything else to it. (bars, headlight, speedo, etc.....)

----- Think some F4I forks sent off to Traxxion or RaceTech will do the trick instead.

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post #38 of 66 Old 10-19-2010, 07:08 AM
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Did someone confirm that the RC51 caliper brackets are a direct swap? RC51 calipers, 320mm rotors, and the RC51 MC would be a nice setup.

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post #39 of 66 Old 10-19-2010, 09:54 AM
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Quote:
Originally Posted by arctic954 View Post
Did someone confirm that the RC51 caliper brackets are a direct swap? RC51 calipers, 320mm rotors, and the RC51 MC would be a nice setup.
rc51 caliper bracket won't bolt up to 919/f4i forks.

RC51 SP2 forks do need some work as they are very soft due to very long and soft top out spring (there is zero preload on the main spring).
SP2 forks are much better made and more superior to SP1 forks, but unless you are planning to rebuilt SP2, I'd go with SP1.
On the side note, it's cheaper rebuilding SP2 forks than F4i/919 forks if you are 180-200lbs rider. SP2 forks have 1kg spring and all you need is to shorten the top out spring and rework stock valves vs. getting new springs for 919/f4i, $120+ savings right there. Of course you can go crazy and install new valves etc but for street rc51 or 919 re-shimmed stock HMAS valves will do more than a good job. The same applies to 919/f4i stock valves. All they need is new shim stack to match/control the spring.

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post #40 of 66 Old 10-19-2010, 12:00 PM Thread Starter
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which is funny..... you hear LDH saying that stock RC51 suspension needs to be reworked in order to utilize its true potential! Have been adding up the numbers.....I'm thinking it would cost well over $1500+ to do it. Seems that the biggest cost and PIA is figuring out the whole tripple clamp issue.... not to mention figuring out how to mount everything else to it. (bars, headlight, speedo, etc.....)

----- Think some F4I forks sent off to Traxxion or RaceTech will do the trick instead.
If you get a set of F4i forks nicely done by Traxxion, you will be happy, and you will not be complaining about the front end at all.

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