One night while browsing through the endless good deals on eBay I stumbled across a front brake rotor from a late model Buell. For those of you that are unfamiliar with the Buell brake set ups they consist of a perimeter floating rotor and a six piston Nissin caliper.
I imagined that it would have quite impressive stopping power so my first thought was, “Could I make it work on my bike?” My bike has no front brake. So the quicker my 250 rear brake can stop, the better off I am. I knew that the Buells have a 17-inch front wheel and my bike has an 18 inch rear, so I had a feeling I could make it work.
I decided to buy the rotor, and ended up winning it for a mere fifty dollars. It even included the mounting hardware. I will be narrating how I made it work for me, but since each bike is different it might not be the best way for every bike. This article is intended to show people that parts don’t have to come in a kit or be made for a specific model to work on your bike. With a handful of creativity you can make anything work.
Designing the mounts and mounting the rotor:
Once I had the rotor I measured the outside diameter and it was just over 15 inches, the inside of the dropped center on my 18-inch wheel is 16.5 inches, so it would fit in my wheel with approximately three quarters of an inch around the outside of the rotor. The mounting hardware consisted of the screws with a special shoulder on them, shims for the steel shoulder bolts to tighten against, ceramic guides for the rotor to slide on, and springs to hold the rotor firmly in the outward position. I wanted the rotor to float because if it was mounted rigid to the wheel, it would surely vibrate. I decided to use the stock hardware; all I would have to do is design a steel mount to weld on the wheel. Ease of replacement was another benefit of using stock Buell hardware. If something should break or be misplaced down the road, just find a dealer.
I researched the stock mounts and found that they are quite simple; they have a threaded hole for the shoulder bolt, a slot for the steel shim that is evenly spaced around the threaded hole, and a blind hole for the spring.
I decided to design the mounts and have them cut by a machinist friend of mine. They can easily be made with a vertical mill, that I have access to, but I knew I had plenty to keep me busy. I was able to determine the spacing between the bolt and the spring by measuring the distance between the wear marks from the spring and the slot for the ceramic guide on the rotor. I guess that’s another bonus of used parts.
Next, I determined the depth for the spring hole by fully compressing the spring and measuring it. I suggest safety glasses when doing this. I made the hole just deep enough to fully compress the spring into it. The threaded hole didn’t need to be blind but I decided that it would look better that way. I made that hole just deep enough to clear the length of the bolt and the tap used to thread the hole. I drew everything in AutoCAD and delivered the drawing to the machinist. A week later I had six steel mounts that were ready to be welded on (Image-2). What’s really great is that they only set me back about $80. Like I said, the guy is a friend of mine.
Next, I started breaking down my spoke wheel. I dismounted the tire and found that a scraper and a wire wheel made an easy job of removing the spoke seal. The seal on this DNA wheel was a foamy rubber that cleaned up nicely. The nipples were then loosened, and in no time the wheel was in 122 pieces. I continued by marking the areas on the rim that the mounts will be welded to and then removed the chrome with a sanding flap wheel attached to an angle grinder. Now I was able to fasten the mounts to the rotor and mock everything up, I definitely liked the way it looked so far (Image-3).
The most crucial step in the whole process came next, welding the mounts to the rim. They needed to be perfectly straight because the rotor is only able to travel .040-inch to compensate for any misalignment. To aid me in this I decided to use a mill table. There won’t be any milling necessary but the T-slotted bed will allow me to firmly clamp everything in place and the spindle will be a perfect spot to mount an indicator. The indicator will be used to make sure everything is straight and concentric.
The easiest way I could find to position the mounts for welding was to bolt them right to the rotor. Instead of using the springs I removed them and used washers on each side of the rotor to hold it in place firmly. This will assure that the mounts can’t slide or move on the rotor. I wanted to have the rotor mounted inside the wheel, exactly one inch away from the edge, so I made some 1-inch spacers to clamp between the rotor and the mill table. Later the wheel was clamped directly to the table which gave me the offset I wanted. The important thing was strict even surface all the way around.
The rotor was clamped to the mill table with the clamps positioned around the outside of the rotor first. Next a test indicator was attached to the spindle and used to center the spindle inside the rotor. This can be achieved by moving the table but once the spindle was centered the table could no longer be moved. After the spindle was centered the test indicator could be repositioned to measure the top surface of the rotor, to test whether it was flat or not. Mine was, if it wasn’t it would need to be shimmed. A cheap set of feeler gauges worked for a variety of steel shims, and if the price was low enough, I didn't feel bad about cutting them up. Once everything was perfect the clamps were moved, one at a time, to the inside of the rotor to make room for the rim (Image-4).
Mounting the rim was fairly simple. It was clamped directly to the table, over the rotor. The rim could slide around on the table while centering it under the spindle. It was important that I didn’t move the table because that would throw off the centerline of the rotor, and I would be forced to start the centering process over. I first measured around the inside of the rim until it was centered; I then lightly clamped it in place (Image-5). You don’t want to over torque those clamps because they will easily bend the rim. After I knew everything was concentric I measured the top edge of the rim to make sure it was also flat.
Once everything was clamped, I began TIG welding by tacking each mount in several spots before fully welding any of them. Since I designed the mounts in AutoCAD they were the perfect length. They came right out to the surface of the rim all the way around leaving just the slightest gap. I welded everything that was possible while it was still clamped in place, that way nothing could be pulled out of position by the heat. The table could be moved to allow extra clearance around the spindle, once everything was centered and clamped (Image-6). I was able to weld three sides of each square mount while it was clamped in place, the fourth outer side needed to be welded when it was unclamped.
After the welding was completed on the mounts and they were thoroughly inspected, I stepped up for a test fit. Everything worked out great. Everything lined up and there was .040-inch of travel in the floating rotor. Once I reinstalled the springs the rotor stayed in the outward position and could easily be pushed to the inward position.
The welds fully penetrated the steel rim all the way around the mounts (Image-7). One of the largest benefits of TIG welding was the ability to add heat without material. That aspect guaranteed full penetration from start to finish. With the fabrication finally done on the rim it was ready to be powder coated (Image-8). The outer edge of the rotor mounts sat flush with the edge of the dropped center in the rim, that was why I wanted one inch of offset on the mounts. There was still one thing that I want to do to the hub before I send it out to be powder coated.
Finishing the hub:
The hub had a flange on the right side for a brake rotor that was no longer needed. Instead of making a cover for it I decided to round off the edges on my lathe and fill in the bolt holes with my TIG welder. First I rough cut the shape with a high-speed steel cutter (Image-9), and then I filed it smooth and finished it with emery cloth and sandpaper (Image-10). Once the holes were filled in with the TIG, I sanded them smooth with a die grinder. I believe this gave the wheel a more finished look than a cover would have and the whole process only took about two hours (Image-11).
After the hub and rim were done I could finally start putting the wheel back together. This wheel already had stainless spokes and nipples so I was going to reuse the originals. I had the rim and hub powder coated gloss black to refinish them. I had never laced a wheel before this project and the tech article here on Bandit’s Bikernet had all the info I needed to get the job done: Click here for Tech
I learned that all it takes is a little patience and you can have a wheel trued up in no time. I started truing up the wheel by using the indicator on the rim. After it was done I used an indicator to measure the surface of the rotor. I kept adjusting the spokes until it had less than .010-inch of side to side movement which will be easily compensated for by the floating rotor’s .040 of travel. I couldn’t find a local place to reseal the rim so I went with a Metzeler tube instead, I’m sure one day I will regret running a tubed tire, but oh well, I’ll deal with that day when it gets here. Last I mounted the tire and had it balanced and I was ready to move onto the caliper.
Mounting the Caliper:
Somewhere during this process I found a good deal on a stock six piston Buell caliper on eBay. I grabbed it for $150, which was nice because they go for about $250 new. I decided to use two counter bored slots to mount the caliper to the frame. I cut the slots out of ¾-inch thick flat steel stock on a mill. I used a piece of flat steel to bolt the slotted mounts together and to hold them in place while welding, this guaranteed that they would be even and parallel (Image-12). They were welded to the frame directly below one another and will allow enough movement to fully adjust the rear axle.
It’s pretty amazing how fast House of Kolor Kandy paint will burst into flames and burn to a crisp when being welded next to (Image-13).
The most challenging step to caliper mounting was making the bracket for the caliper. This is the step that will vary the most depending on the type of frame and rear suspension. I already had a lot of twisted steel parts like my sissy bar, forward controls, and other linkage pieces, so I decided to make the bracket out of twisted hex stock too. Tubing would have been stronger and would probably be the best material to use but I knew twisted hex stock would be strong enough if I made it right.
The biggest challenge was getting the bracket around the sprocket. The bolt-holes on the caliper are actually behind the sprocket so my bracket has a U shape to it to get around the sprocket. It also has a third link to tie it to the axle, which will make it stay the appropriate distance from the rim. I made a wheel spacer out of steel so I could weld the bracket right to it. It would have been way easier to put the brake on the right side because then the caliper bracket would have been a straight shot and could have probably been machined out of one piece of steel. I put everything on one side of the wheel because I believe it looks better and I looked forward to the challenge of mounting it.
There was no high-tech tools used to make the bracket. I twisted the steel by using an acetylene torch and a long crescent wrench, and I cut the stuff down to size using a ban saw and a grinder with a cut-off wheel. The only piece of equipment I used that isn’t in most garages is my lathe, which I used to make the threaded round parts and spacer. I used an old master cylinder to hold the caliper on the rotor exactly where I wanted it and I started slowly putting together the bracket one piece at a time. Everything was trial and error as I tacked each piece in as many places as possible while it was on the bike, slowly, so I didn’t let the caliper get too hot. When it was finally pieced together I pulled it off to finish welding it. The finished product is very strange looking, but fits the bike exactly as it needs to-it clears the chain and sprocket and connects to two spots on the frame, two on the caliper and one on the axle. (Image-14, Image-15).
This mount works great for me, but as I said before the mount will vary depending on the application due to differences in frames, swingarms, and mounting methods.
The Final Assembly:
When I started putting everything together it all went very smooth. I red Loctited everything that can be heated when I need to remove it. I reattached the brake line and bled the brake system. When I started tightening the chain I did notice that the wheel needs to be perfectly straight or the caliper will drag on the rotor, after some fine adjusting I got the drag down to a minimum (Image-16).
I’d be lying if I said I wasn’t nervous when I tested it, nobody cobbles together a brake system out of other people’s used parts and puts their life on the line without getting at least a little nervous. I am happy to say that it worked great, better than I expected. I can jump on the brake peddle and lock up that big 250 tire in an instant.
All it took after the final assembly was a little bit of adjusting and one more bleeding process, and it was trouble free. A friend and I rode down to the Smokeout in North Carolina and back last June and it worked great. We even rode through Deal’s Gap on the way back, and I’m convinced that nothing will test brakes as good as the Dragon’s Tail–those curves were intense. It did get hot, which caused the peddle to softed, but once it cooled down the brakes came back and were as good as ever.
I’ve tested this brake for an entire riding season now, and I’m confident enough to spend the bucks to get the caliper bracket chrome plated, and I may even repaint the bike.
This article was written to show, not only, that motorcycle parts don’t have to come in a kit for a specific application to work, but also that they don’t have to cost a lot of money. The total cost for this entire brake build, including the powder coat on the wheel was $360. Even if I add the cost of the brake lines and the master cylinder which were part of the original set up, it would be less than $500. With all the money saved I will eventually tear it down and repaint it. The only problem I'll face will be the down time. It’s just too damn fun to ride.
More pictures of this bike and the modifications that were made during this brake project, as well as other parts I have made are available on my website: www.choppinsteel.com.
Before pictures are also available in Wrench’s Bike Barn: Click Here for Feature.
–Eric Barnett
http://www.choppinsteel.com
(810)-252-8386
