Calling all radial m/c's, come to papa, show me what ya got.

[Pat Conlon]

The next step up from the 14mm m/c's would fitting the FJ with a radial designed m/c both for the brake and clutch m/c's. Just by the nature of the design the radials would be superior over the conventional right angle m/c's....so,

Who's got 'em? Fess up. Need all the details. Which bikes did they come from? Post some pictures and I promise I will not make fun of your urine cups....  

TIA Pat

[dixiethedog]

The radial master cylinder has been going thru my mind recently. A friend of mine,who rides a zx9r Kawasaki has fitted a radial master cylinder kit to his bike and reports the improvement is incredible.
Today i just received (from the post office)an Aprilia RSV1000 clutch master cylinder,with remote reservoir,so im going to give this a try to see how it works. (its not a radial,but it allows me to use Renthal type bars and risers,with a full fairing).Ive just this week managed to buy some 6pot calipers(hayabusa???),to fit to my TL1000 front end (on the FJ),which is using my friends original zx9r master cylinder,so,i'll see how things go,and like you,look into radial stuff at a later date.

[rktmanfj]

I promise I will not make fun of your urine cups....  

TIA Pat

Mine don't look like urine cups...  (DOT 5)   

Randy T
Indy

[axiom-r]

Here's what I have to deploy on this rebuild.  I don't know if there are any fittment issues yet but they look good!




2007 R1 Radial Brake Master Cylinder. A Brembo unit that comes with the 6 piston calipers - stock R1 stuff.


1994 YZF750 Radial Clutch Master Cylinder. 


Huh. They do in fact look like urine cups.... 

[the fan]

 I run a radial brembo off a late model R1 (R6 is the same) and it is a bug improvement over the yamaha/nissan 14mm master. Great power and feel.

[JCainFJ]

 I have been using the 19mm radial master (made by Nissin) from a 2004 GSXR 600 on my YZF600. It provides improved feel and controle vs the 14mm R1/R6 master I had been using. One of the best features that the radial Nissin master has is the bleeder located at the top of the bore. It makes for very quick purging of any air. The 5 position adjustable levers are nice too.
I have also purchased a set of Nissin radial masters from a Kawasaki ZX14. The brake master is a common Nissin 19mm radial, so lots of Kawasaki, and Suzuki levers will fit. The clutch master ( again a Nissin part) is a near mirror image part to the Brake master. It is marked as being a 3/4in bore.  The bigger bore of these radial masters works out to be the equivalent of the non radial masters I had been using.
I have also made up a few remote reservoir mounts for the clutch side, simple clean parts like always.

[axiom-r]

I have also made up a few remote reservoir mounts for the clutch side, simple clean parts like always.

I would love to see your res mounts- I am going to have to figure some out soon!

tim

[JCainFJ]

 I will try to post some photos soon.

[Pat Conlon]

...... The clutch master ( again a Nissin part) is a near mirror image part to the Brake master. It is marked as being a 3/4in bore.  The bigger bore of these radial masters works out to be the equivalent of the non radial masters I had been using.

Let's talk about that for a minute.....Help me out.   Bore equivalences between radial vs.non radial m/c's.  How does that work?

I know thru experience that with conventional non radial m/c's when we replace our~16mm (5/8") m/c with a smaller 14mm m/c we get a lighter 2 finger action on the lever, yet with a longer stroke.

So how is it that we use a larger bore with radials and get even a lighter lever feel?  Is it all due to mechanical efficiency of the radial, i.e. having the piston travel in parallel to the stroke of the lever. That much?  I mean a 19mm radial m/c having a better feel and lighter touch than a 14mm?
14mm piston area=154 vs. 19mm piston area=283  so a master cylinder with a piston area 80% larger, yet with a lighter feel, all due to mechanics?

14mm vs 5/8": I was just getting my head around how a smaller piston with a longer stroke can give a lighter feel or pull at the lever, now you turn my world around and tell me a larger piston will be fine.....

[JCainFJ]

 I think that the geometry is quite a bit different radial to non-radial. The distance from the bore to the lever pivot is shorter on the radial master, so a given movement at the lever moves the piston a shorter distance. That's why the piston has to be bigger.
I have also noticed that the radial masters deflect less then the in-line masters do. That may be why the radial masters provide better feel. Braded lines eliminate the flex (think of it as a spring) of rubber lines and that provides better feel. The monoblock calipers flex less then the earlier bolt together 4 piston calipers and provide better feel too.
I actually mounted a dial indicator (CA is great stuff) to one of the stock calipers on my FJ and then to an early monoblock and found that the monoblocks flex about half as much as the stock FJ calipers. (We have some long winters here in Cincinnati)  Some of the older calipers you can actually see flex when you apply pressure.
One of my pet long-term projects is designing better clutch and brake hand controles. The OEM,s have done some work on these systems, but I think there is still a lot to be done.

[Pat Conlon]

Ok, thanks Jon.  Geometric efficiency, got it, it makes sense.

What I was looking for was some sort of rationale or logic in between choosing a 12mm or 13mm or 16mm or 20mm pistons offered in a radial m/c's.
For example, look at Spiegler's offerings: http://www.spieglerusa.com/brakes/radial-master-cylinders.html  Which one should I get to mate with my R1 calipers?
Does the volume of the calipers and/or the surface area of the caliper pistons dictate m/c piston size?

Looking at Tim's above pictures showing the Brembo m/c; does the stamping indicate that this m/c uses a 16mm piston?

Thanks, Pat

[racerrad8]

If there is interest in new radial brake master cylinders, I know that one of my vendors carries the Nissin units. I talked with him many moons ago and if my recollection is right, he said they were 19mm.

If there is enough, I will start doing some leg work on size, price & availability.

Let me know,
            Randy - RPM

[JCainFJ]

 Pat,

Yes that Spiegler stuff is nice. They are just up the road from me in Dayton, I know them.

You will have to contact whoever makes the master you are interested in and ask which master size is best. They all have there own geometry. I do know the Nissin brake master for a total of 8 pistons is 19mm. Suzuki recently changed the spec for the Nissin master they use on the GSXR's, so the newer ones may differ.

Does the  surface area of the caliper pistons dictate m/c piston size?

Yes the total surface area is (I think) the main factor.

Looking at Tim's above pictures showing the Brembo m/c; does the stamping indicate that this m/c uses a 16mm piston?

Yes it looks like that may be so. It will be interesting to hear how that master works. If its too small he will know it right away! I've mounted an F3 front wheel on Cynthia's Hawk with a pair of R1 monoblocks, and we tried the stock Hawk 12mm master. It was way to sensitive and we ended up using an r1 14mm master.

[Pat Conlon]

. They all have there own geometry. I do know the Nissin brake master for a total of 8 pistons is 19mm. Suzuki recently changed the spec for the Nissin master they use on the GSXR's, so the newer ones may differ.

Yes it looks like that may be so. It will be interesting to hear how that master works. If its too small he will know it right away! I've mounted an F3 front wheel on Cynthia's Hawk with a pair of R1 monoblocks, and we tried the stock Hawk 12mm master. It was way to sensitive and we ended up using an r1 14mm master.

Ok thanks Jon, so for the 8 pistons in my pair of R1 monoblocks, should I use the 19mm or the 14mm like you used on the Hawk? I do have a call into Spiegler.

TIA

[axiom-r]

I am pretty certain that the Brembo unit off the R1 is a 16mm as stamped.  

And help me out guys- is the clutch M/C shown a radial unit or not?  I am thinking not....

tim