Retrofit: Radial Master Cylinder

[ds650rida]

I have really been hellbent on putting a radial master cylinder on my girlfriend's 250. A radial master cylinder has lots of advantages over a conventional type as on our 250's and many older bikes. I wont get into them but if you're in for a long read, I have an informative link here:http://www.ducati.ms/forums/80-hall-...cylinders.html

While I do want my girlfriend to have safer, better performing brakes, my main concern was to make space on the bars. The stock master cylinder forced the mirror brackets to an awkward position that's a few inches closer to the rider.

I was taking a shot in the dark here but I needed to know if this would work or not, so I tried my best to document it. I will begin with a parts list:

1 - Radial style master cylinder. (The one I chose is from a 05-06 zx6r like mine. Most others will probably work, I'd stick to kawi parts to ensure the thread pitch for the banjo is the same. I took a shot in the dark here as far as the piston size is concerned)

2 - Custom brake line (I plan to order from Spiegler http://www.spieglerusa.com/ a regular line for this bike with a 90 degree bend on the top fitting. A STOCK LINE WILL WORK IN A PINCH BUT IS NOT RECOMMENDED)

3 - Brake fluid reservoir

4 - Brake lever (choose for make & model you got the master cylinder from. duh)

DISCLAIMER BRAKE FLUID IS CORROSIVE AND WILL SCREW UP ANY PAINTED SURFACE IT COMES INTO CONTACT WITH. HAVE WATER & BRAKE CLEAN READILY AVAILABLE TO CLEAN UP ANYTHING THAT SPILLS. BRAKE FLUID SHOULD BE TREATED LIKE HOT LAVA. PS, I'm not responsible for you getting brake clean in your eyes or crashing your bike and dying as a result of this mod. If you're not competent enough to perform this procedure, then pay someone else to do it for you and that way you'll have someone to blame.

Here is the master cylinder I purchased. As I said above its from an 05-06 636. I chose this so I could use my bike as a reference and steal the lever for the time being.



In this picture below you can see how much of a radical angle there is on the brake line. This brake line also has a double banjo fitting on the end because it feeds 2 calipers instead of 1 like we have. If this line is still attached remove the banjo bolt and discard of both. (may be a good idea to hold onto the crush washers)



First step is to remove the fluid from the brake system. If you have a hand held vacuum bleeder this is a piece of cake, otherwise you will probably have to remove the banjo bolt on the caliper and allow it all to drain out. Once all the fluid is out, crack loose and remove the banjo bolt from the master cylinder and make sure you keep track of those washers.



Then loosen the bolts holding the master cylinder onto the bars and pull off the wires for the brake light switch. Then take the master cylinder off.

Below, you can see the difference in width between the stock and radial master cylinder clamp areas. My stock clamp was modified to begin with, your stock one will probably have little tabs on either side.



Next thing you'll want to do is screw the banjo bolt and fitting into the radial master cylinder by hand. Make sure you use the bolt that you removed from your stock master cylinder and have 1 washer on either side of the fitting.

This is the part where a custom brake line is necessary. While using the stock line, I needed to bend the line back in order for the fitting to face the right direction to be secured onto the master cylinder



This is why starting the threads while the master cylinder is off the bars is necessary. There are 2 tabs on this master cylinder that locate a pin on the stock brake line. I have the 250 brake line outside of these tabs between the brake light switch










Now install the master cylinder onto the bars and tighten the clamp. On my bike, since I have a bracket for a mirror, I have run into clearance and adjustability issues. As long as there is nothing extra on your bars, you shouldn't have any problems.



Here it is installed





Now make sure everything is tight, add fluid, bleed the brakes and check for leaks. Don't forget that you now have a new bleed location here on the master cylinder as well.


Reactions & Thoughts:

I was pleasantly surprised to find out that the piston in this master cylinder matched the caliper so well. There is very little free travel in the lever and it doesn't pull all the way to the bars like before. Judging from just rolling around the garage, they don't feel too touchy either. Tomorrow I will take it for a spin and update this accordingly.


*UPDATE 4/25/14*
Took the bike up and down the driveway today. Got into 2nd gear. Brakes feel predictable and controlable. I dont plan on doing any stoppies anytime soon but no more crushing my fingers. 2 finger braking is more than possible and im sure that I'm flexing the stock 10 year old lines. Also im sure there is still some air in the system. More when I get stainless lines.

[Alex]

Nice work!

[ds650rida]

Took the bike for a ride. Update in op

[ds650rida]

Got the new stainless line and modded the mc. Pics to come

[ds650rida]

Ordered up a spiegler front brake line. Specs are
762mm length
072 fitting and 002 fitting.

I could have gone shorter on the length by a few inches perhaps and I think I would have prefered a 90° bend instead of the 70°.

[ds650rida]

There are 2- 1.5" stretches of aluminum that need to be cut off. These are to locate a pin on the oem brake line. I just cut them even to the mounting surface of the brake line




I also had to take material off of the inside by the clamp to fit my specific application. I have a clamp for a mirror that I need to make room for. I would definitely test fit first and massage the metal for adjustability purposes. At no point did I break through the aluminum and I took quite a bit of material off

[ds650rida]

I bent the stock mount for the master cylinder 90° to mount onto the clamp. It is visible and upright but out of the way. An eBay brake lever finishes off the package.

[ds650rida]

My new impressions:

"Holy ****!" Was the first thing that blurted out of my mouth. This lever is stiffer than my 636 with nissins and ss lines. The lever feel is super solid. I was able to brake so hard that the oil light flickered. This mc is trying to push enough fluid for 2 large 4 piston calipers and cramming it into a small 2 pot. Aside from the amount of bite it is controllable and predictable. A full fist on this lever is too much. 1 or 2 fingers are a must. I'd call this a must have for track guys and definitely a great safety mod for the street. Any questions feel free to ask

[Singh2jz]

Originally Posted by ds650rida

My new impressions:

"Holy ****!" Was the first thing that blurted out of my mouth. This lever is stiffer than my 636 with nissins and ss lines. The lever feel is super solid. I was able to brake so hard that the oil light flickered. This mc is trying to push enough fluid for 2 large 4 piston calipers and cramming it into a small 2 pot. Aside from the amount of bite it is controllable and predictable. A full fist on this lever is too much. 1 or 2 fingers are a must. I'd call this a must have for track guys and definitely a great safety mod for the street. Any questions feel free to ask

Looking good. Thanks for the write up and review. I'm looking forward to doing something like this.

[crazymadbastard]

nice mod, definately doing this.

[krolinked]

I did this mod but I'm not getting crazy stopping power. Instead I got a very hard to pull lever which I have to death-squeeze, just to stop normally.... What the heck.