Greetings!
I have a set of Brembo P34-4 piston calipers (pic below) that I believe were standard for the 748/996/998 series bikes. Does anyone know what the best master cylinder is for these calipers? In particular, what is the best master cylinder piston bore size? 17mm? 19mm?
Thanks,
Dave
(http://i34.photobucket.com/albums/d147/pompino/IMG_9716_zpsgwdr94im.jpg) (http://s34.photobucket.com/user/pompino/media/IMG_9716_zpsgwdr94im.jpg.html)
I have those on my SBK and they work great with a standard Gold Line master, which I believe is 16mm. Maybe something different would be better...dunno.
Those are "999" calipers. Nice, (but) with a healthy initial bite because of the four pad leading edges.
What are those brackets?
When I changed from 16mm coffin to radial master from a StreetFighter 1098 (19mm, I think...) I was very surprised that it was such a minor change. YMMV.
Wow, thanks for the speedy replies! [thumbsup]
Lars - the adapters are for a new Bandit project. :P I've used radial masters with axial brakes and I too was surprised at the improvement.
1216 pistons, Web 236 intake cam:
(http://i34.photobucket.com/albums/d147/pompino/B6F298FC-A4E2-4A26-A1E4-04216E84DBF1_zpsrrkph2so.jpeg) (http://s34.photobucket.com/user/pompino/media/B6F298FC-A4E2-4A26-A1E4-04216E84DBF1_zpsrrkph2so.jpeg.html)
(http://i34.photobucket.com/albums/d147/pompino/C80D94C5-2D5D-41D0-BEF6-6607AD295957_zpsoz7xlmbm.jpeg) (http://s34.photobucket.com/user/pompino/media/C80D94C5-2D5D-41D0-BEF6-6607AD295957_zpsoz7xlmbm.jpeg.html)
'88 GSX-R750 fairing and chopped up RGV-250 tail (no worries, it was aftermarket!).
(http://i34.photobucket.com/albums/d147/pompino/fullsizeoutput_798_zpsyxw3ggvl.jpeg) (http://s34.photobucket.com/user/pompino/media/fullsizeoutput_798_zpsyxw3ggvl.jpeg.html)
R1 swingarm brace welded onto an RF-900 swingarm. M-Unit equipped...
(http://i34.photobucket.com/albums/d147/pompino/57030655672__64C610CD-077E-4775-B351-DF1054EF2663_zpsyvinpanl.jpg) (http://s34.photobucket.com/user/pompino/media/57030655672__64C610CD-077E-4775-B351-DF1054EF2663_zpsyvinpanl.jpg.html)
I don't find the initial bite all that aggressive on the 4 pads with HH+ pads, compared to the really aggressive bite with race pads and 2 pad calipers.
That's just me.
Thanks Nate, that's helpful. I will take this bike to VIR, but I ride in the beginners group and most of its duty will be street and I don't want too much initial bite.
I've got those calipers with Ferodo CP1 pads, 16mm goldline master, and BrakeTech iron rotors.
They're stellar! [thumbsup]
Quote from: Speeddog on February 02, 2019, 07:23:19 AM
I've got those calipers with Ferodo CP1 pads, 16mm goldline master, and BrakeTech iron rotors.
They're stellar! [thumbsup]
Awesome, thanks!!
Radial masters have different leverage ratios than goldlines/small pivot, which have different leverage than coffins/big pivot.
I'd wondered about why a 16mm coffin felt squishier than a 16mm goldline, examining the drawings showed the coffins have more leverage on the piston.
Brembo muddied the waters of that trend with the radials, which have even more leverage, but with generally larger pistons.
Drawings representing each style:
Radial:
https://www.oppracing.com/images/cmsuploads/Brembo/OEM_Schematics/oppracing%2010-8210-10%20brembo.pdf
Small pivot:
https://www.oppracing.com/images/cmsuploads/Brembo/OEM_Schematics/oppracing%2010-6870-18%20brembo.pdf
Big pivot:
https://www.oppracing.com/images/cmsuploads/Brembo/OEM_Schematics/oppracing%2010-5053-16%20brembo.pdf
If we take the distance from the pivot to their approximate "index finger position", divided by the distance from the pivot to the piston bore axis:
[18/19] Radial - 98/19 = 5.16
Small pivot - 77/24 = 3.21
Big pivot - 75/22 = 3.41
Then divide those numbers by piston area, we get:
[18/19] Radial = 0.0203
Small pivot = 0.0160
Big pivot = 0.0170
Bigger numbers mean more net leverage.
Further muddying the water is (my suspicion!) differences in piston seal/bleed hole arrangements.
The coffins seem to require the most lever travel to 'harden up', small pivots are better, and radials better yet again.
Additionally, Brembo has produced a bewildering array of radial configurations; [17/18], [18/19], [19/16], [16/18], [19/20] etc, etc.
Just those 5 have net leverage numbers ranging from 0.0173 to 0.0271.
IMO, they could have had a logical and clear family of piston/leverage combinations, rather than the seemingly random combinations they have.
Perhaps I've just not been able to break their code...
Yet again, Italy has decided to not contact me for help [laugh].
I'm going to try to make a bit of sense of their selection.
The math...already so far...has my head hurting. ;) How do large pivot Goldlines fit in?
I'll stay with my antique equipment. This dinosaur is familiar with it.
Two links to the small pivot?
Quote from: stopintime on February 02, 2019, 11:51:32 AM
Two links to the small pivot?
Of course! :P
Post corrected, thanks!
Quote from: ducpainter on February 02, 2019, 11:13:05 AM
The math...already so far...has my head hurting. ;) How do large pivot Goldlines fit in?
I'll stay with my antique equipment. This dinosaur is familiar with it.
From the data I've collected so far, the big pivot masters are all the same geometry on lever/pivot distances.
So gold, black, coffin all the same.
It is Italian hardware, so they likely have some masters that don't fit that summary....