Just_Nick

I am trying to do some research and need some info.
Could you guys with RC51, F4i, GSXR, etc calipers measure the diameter of your caliper pistons and post your results along with model info? I am trying to figure out which calipers have the largest surface area.
Thanks
Nick

Syclone

I'm not trying to post the typical "do a search" message, but I think either Lazn or Inde already posted this info in a thread about which brake components are bolt-on mods. I'll try to find it.

Syclone

Info posted in here: https://www.superhawkforum.com/forum...=bolt-on+brake

cliby

just curious what you have in mind comparing the surface areas? Not sure it correlates with much when all other variables are taken into account.

I just tried to measure the stock SH pistons without disassmbling them and get about 28 and 30mm if that is any help.

Just_Nick

I am trying to figure out what the total surface area of the pistons is. I am using it to help calculate pressure of the system. Obviously real-world testing might be more effective, but this should be good enough for me. Obviously a larger bore MC will create more pressure, however it is at the expense of requiring more force from the user. On the other hand a smaller bore cylinder, like the stock one, needs to travel further to create an equal amount of pressure, hence the amount of lever travel experienced even when bled perfectly.
Same goes for the calipers in theory: larger diameter pistons are able to exert more force per x amount of travel.
I need a braking setup which is able to stop the SH with only a single caliper.

It looks like I'll go with a 929 or rc51 master and rc51/f4i calipers.

mikstr

the best leverage set-up is the F4i (largest caliper pistons and smallest MC piston). As far as the 4 vs 6-piston comparison, although I have not tried them side by side to confirm it, I have reserached it a bit and found comments from others who have and the general consensus is that the Nissin four-pots used in the Hondas are superior to the earlier 6-pod Tokicos used in the GSX-Rs. Hope this helps.

Just_Nick

They're superior because they have a larger surface area, which can put more pressure on the pads.
With the F4i master you get more leverage because the smaller diameter piston needs to move further to displace the same amount of fluid as the 19mm. On the other hand, you need a lot more finger strength for the RC51 master.
If I wanted good leverage, I could stay with the stock master(it's 14mm).

mikstr

I am running 98-99 900RR calipers, a Nissin radial MC from a late-model ZX-6R, steel lines and HRC hard bite pads and can lock the front end at will a any speed. In fact, the only bike I rode that has more bite is a 1098S.

sounds as though you have your mind set on a set-up anyhow so do what you want....

Just_Nick

I'm only going to be running a single caliper though, so I need as much power as possible.

cliby

i think its a fine line, and somewhat subjective, as too how much 'leverage' and power you want. At the one extreme too small a diameter MC and too large surface area can mean excessive travel which can be interpreted as lack of power and make it tedious to brake hard. the other extreme is very little travel but requiring huge strength to approach pressures to lock the wheel. If you are going with one caliper see if you can upgrade to a larger rotor also - there are some easy fitments I believe.

Just_Nick

Does anyone know what larger rotors fit the SH wheel?

killer5280

I personally would start with more leverage. Having to use King Kong grip strength to generate power gets old quickly. With only one rotor it's going to take some experimentation anyway to get the setup right.

Just_Nick

I'll use the SH master first then, since it has "more leverage".

mikstr

If you`re only using one caliper, even the VTR piece may be borderline. Let me know if it`s too stiff, I have a master from a DT200R that has a 12.7 mm (1/2") piston diameter that I am not using.

Hawkrider

You want to find the smallest diameter M/C you can and couple it with the largest caliper piston surface area you can find that will bolt up, which may very well be the 6-pots.

Just_Nick

First generation RC51/F4i have the largest piston surface area, I calculated it.
F4i: 1711.3mm^2
GSXR: 1596.69mm^2

And that is per side per caliper. Multiply those by two to get the total surface area of both sides of each caliper.

inderocker

Wow, wouldn't of guessed that!