Aftermarket Brakes for CBX

Rick Pope · Post by **Rick Pope** » Mon Jul 27, 2009 8:20 am

Randakk,
I'm not a trained engineer, but I have a question that's bugging me.

Have you considered that the bolts holding this assembly to the wheel now will have a much greater force acting upon them? They were originally designed with a margin of safety, but with this much braking force, you might exceed that margin, by a bunch. It would be SO disappointing to grab a fist full of brake and shear those bolts.

That said, it sure looks nice.

cbxtacy · Post by **cbxtacy** » Mon Jul 27, 2009 9:28 am

Rick, I do not believe the tires available in a 19" would exceed the limitations of the bolts. I'm starting to save up my pennies. Every time I replace my front tire on my stock 82 I replace my front brake pads. Why? Because they need it.

alimey4u2 · Post by **alimey4u2** » Mon Jul 27, 2009 11:05 am

Interesting one this...

The distance of the force hasn't changed ( tire diameter) but the distance of the effort ( brake pad position/radius) has... The load is the same but the fulcrum on the lever has moved, thus requiring less effort for the same effect...

Sooo... In theory, would the forces on the "lever" remain the same ??

I do agree with George on this though, the tire & then the forks are the limiting factor..

dgfischer · Post by **dgfischer** » Mon Jul 27, 2009 11:33 am

Randakk, Thanks for posting the slideshow. I had to sign up and wait for my approval before I could post. Jeeze, They'll let anybody in here.

I dont have any stock CBX items (calipers and discs) to do a weight comparison to the new kit, but for comparison. on my CB 750 SOHC (with a GL 1000 front end) I lost about 6 lbs of unsprung weight when I changed the brakes to Tokico 6 piston and 310mm discs. I could loose another 1.5-2 lbs if I changed the calipers to Nissin 2 piston calipers (like what is on Randakks RC003), but since it is a "rolling bilboard" for my brake kits, "overkill" works/looks better and gets noticed more.

The disc mounting bolts will be fine as the only limiting factor is the tiny patch of tire that is in contact with the road. The stock CBX disc bolts will probably be replaced with a set of allen head bolts as this kit has very tight clearances(especially for the speedo drive).

I'll be adding more pics to the slide show as the kit progresses. It should be completely done this week.
DG

alimey4u2 · Post by **alimey4u2** » Mon Jul 27, 2009 12:14 pm

DG, first of all..welcome to the site..

Will the stock master cylinder assembly work well with the different/new hydraulic ratio ??

Rick Pope · Post by **Rick Pope** » Mon Jul 27, 2009 2:31 pm

Hmmmm. Makes sense that the contact patch is the weakest link here. Hadn't considered that.

I too have a SOHC w/ an early GL1000 front end. Had it at Vintage Daze. The brakes suck, even with the 5/8 CBX master cylinder. Since I'll have the front wheel stripped down for stainless spokes next winter, I might think about a brake upgrade........

Randakk · Post by **Randakk** » Mon Jul 27, 2009 3:26 pm

Good comments above.

I plan to make a weight comparison as soon as the new components arrive.

Right now, I'm separated from the target CBX and the new brake set-up by about 2000 miles. I will be back from my Colorodo outpost to my main NC location in about 2 weeks. I hope to have the new brakes installed in time to show them at my Rally in late Septemeber (in Bedford, VA).

The hardware Dan selects is matched to the task. In this case, it's a rather moot point, since the potential forces that can be generated will be severely limited by available front tire traction.

That's actually my strong preference for my style of riding. The are many reasons I'm doing this:

1. I like something different
2. I prefer lots of max brake force (again limited by the front tire)
3. Weight reduction....and all the handling benefits that delivers

But, the main reason I'm doing this is the extra brake power allows for much better modulation and "feel" as various limits are approached.

This is not wishful thinking. The "Fish Head" big brake conversion Dan built for my supercharged GL1000 delivers all those advantages.

Initially, I will run the excellent Nissin front master cylinder (from my catalog). I generally put that unit on all my bikes (except show bikes). The CBX already has one of those. The adjustability and "feel" delivered by that unit is excellent and well-matched to the upgrades underway.

Eventually, I plan to try a radial master cylinder on the CBX.

By the way, my CBX has modified Interceptor bars that are about half-way between regular OEM and "sport" bars. I'm running a Euro right switch assembly that has top-exit throttle cable routing for gas tank clearance. Again, this was all done to "fit" my preferred riding position

The bars are 1 1/2" wider than stock Intercepter bars for more leverage. CBX power steering!

EMS · Post by **EMS** » Mon Jul 27, 2009 4:20 pm

If you have a 39mm fork (which I assume you do), you can also use the 81/82 Prolink handlebars. They are lower than the 79/80 bars but higher and wider than the sport kit bars.

Randakk · Post by **Randakk** » Mon Jul 27, 2009 4:26 pm

EMS wrote:If you have a 39mm fork (which I assume you do), you can also use the 81/82 Prolink handlebars. They are lower than the 79/80 bars but higher and wider than the sport kit bars.

Yes.

I already ditched the 81/82 Prolink handlebars (the bike is an '81 with 39mm forks).

The news bars I built are slightly lower and have an better "wrist angle" (at least for me).

Plus, the modified Intercepter bars offer less "interference" and much better master cylinder mounting options.

dgfischer · Post by **dgfischer** » Thu Jul 30, 2009 8:02 am

Good news and not so good news.
Good news = It's done
Not so good news= The wife went to the cabin with her girl friend and took the camera with her so there are no pics of making the caliper brackets. She got home last night and I took the pics of the completed assembly.

But it's done. The disc adaptor for the right side had to have the holes for the nuts opened up to accept a socket (for putting on the nuts for the adaptor mounting bolts) and the little "vents" in between the 330 disc mounting bolts have been opened up to give it a more "open" look. The adaptor has also been shaved down to the height of the hub/bearing retainer.

Clearances are very tight on the speedo side.

I added a few more pics to the slide show.

DG

Randakk · Post by **Randakk** » Wed Aug 19, 2009 7:08 pm

The Fish Head Big Brakes have arrived and they are a work of art!

I hope to have them on the road soon. They will definitely be on display at my Rally in Beford, VA ... Friday, September 25 - Sunday, September 27, 2009.

(follow the Rally link on my site for details)

alimey4u2 · Post by **alimey4u2** » Wed Aug 19, 2009 7:18 pm

They look great.....

Randakk · Post by **Randakk** » Wed Sep 02, 2009 4:28 pm

I've just finished the install of the "Big FishHead" front brakes on my CBX that I sourced from my friend Dan Fischer. These have 330mm rotors and 6 piston AP Racing calipers (each side).

I managed to get everything bled and took a 10 mile trip shakedown trip. I was very careful at first and gradually worked up to some very aggressive braking. I now have way more brakes than tires :) which is what I was expecting. It suits my riding style.

Impressions:

1. Fantastic power
2. Very low effort at the lever is required...basically it's a "one finger" setup. If I had more nerve and skill - stoppies would be easy...even with this heavy bike!
3. It stops right now! almost telepathic braking
4. Better: there is great "feel" and modulation

And this is all compared to an excellent OEM setup I just replaced that included an upgraded Nissin brake master, EBC pads and braided lines.

I calculated about 5 pounds of total weight savings. Removing that much unsprung weight and gyro effect is very noticable. Steering seems much more sensitive. The whole front of the bike seems much lighter.

There are many, many very tight clearances that have to be painstakingly checked and shimmed, so it was a bit of a "science project" to get them installed correctly.

Thanks to Dan Fischer for an excellent fabrication job!

P.S. I'll be showing these off at my Rally the last weekend of September in Bedford, VA. I hope to post some pix soon on my site.

Don · Post by **Don** » Wed Sep 02, 2009 7:51 pm

dgfischer wrote:Good news = It's done

The disc adaptor for the right side had to have the holes for the nuts opened up to accept a socket (for putting on the nuts for the adaptor mounting bolts) and the little "vents" in between the 330 disc mounting bolts have been opened up to give it a more "open" look. The adaptor has also been shaved down to the height of the hub/bearing retainer

Nice! I'll bet she stops on a dime

My opinion - It would look better if you had the home made brackets powdercoated black, along with the associated hardware. Anything you could do to reverse the fork to adapter hardware so that you don't have the nuts with half a dozen threads sticking out would be good too - Some black allen head screws there would look much better

Don

dgfischer · Post by **dgfischer** » Thu Sep 03, 2009 8:28 am

That's why I didn't polish the brackets, Don.

I have polished a few brackets for my brake kits, only to later see the same brackets spray painted black. It was then that I realized that the final finishing is up to the owner. I REALLY hate polishing stuff (especially when it is only going to get spray-bombed later).
My bolt supplier doesnt have 45 mm bolts when I made the kit and that is why there is extra threads showing(50mm bolts). The caliper mounting brackets are 1/2 inch thick and I could have used 40mm bolts to hold them on (and been flush with the outside of the brackets), but I would rather have the longer bolts with the added security of a lock nut on the outside, especially with the big CBX. I really doubt that the added security of the lock nuts is needed, but I would hate to find out that they SHOULD have been used, after it is too late. This particular kit has VERY tight clearances everywhere and I feel more comfortable with the extra locknuts on the outside securing everything in place.

Randakk, glad you like the kit. The braking of those AP calipers should be light years ahead of the stock CBX calipers. If you are anything like me, you now have more brakes than "rider skill".

Thanks again,
DG