Red Rider's Sand Machine Updated 07/23/14
Now that we all know I'm making a pair of brake disc adapters for my brother's 250R's inverted forks, and mine as well, here's the background story. My brother needed me to scan my custom front wave rotor. I had gotten this rotor from an eBay seller, that was making custom ones for 250R's, back in 2002. By the time my brother decided he wanted one, we couldn't find the seller on eBay anymore. Basically, my bother wanted a scan of my disc, to give him some design ideas for some custom discs that he was planning on having made. Now, when I first did the inverted forks on my 250R many years ago, I kind of rushed the front caliper mounting setup. I used the same KTM Brembo caliper, that Billy Golightly used on his Tri-Z's inverted fork setup, because it looked like it would work well for my application also. When I mounted the caliper, I couldn't quite get it in the ideal postion for total pad coverage, but it was good enough for the time being. Because of my haste, I knew as the pads wore down, they would eventually touch together, and no longer be able to apply clamping pressure to the disc. I had planned on coming back, to correct that issue, at a later time. Instead, I got lazy, and left it alone.
While removing my front disc, and seeing my pad's wear pattern, I was reminded of this misstep all those years ago, and it bugged me. Sure the pads were barely worn, and would probably never touch together in my lifetime, but it still bugged me. It must be that, attention to detail, OCD thing, that I have. One of the easiest ways to correct this, was to go with a larger, off-the-shelf, wave rotor from Galfer. I would then make a relocation bracket for the caliper to mount to (kind of like the oversize wave rotor kits for dirt bikes). First, I searched Galfer's website for disc dimensions. The stock 250R disc is 203mm OD, but I needed something slightly larger. I found a few 205mm, and 210mm discs, but they were a bit thin (3mm). There were quite a few 220mm OD discs, and as a bonus, they were 4mm thick. I made a wood disc that was 220mm OD, and bolted it up to check caliper-to-wheel clearance, and then caliper bracket-to-forkleg mounting clearance.
The 1st pic shows the brake pad's wear, due to my hasty, improper caliper mounting.
The 2nd pic shows the caliper clamped onto the 220mm wood disc (in the proper position for total pad coverage), so I could check caliper to wheel clearance.
The 3rd pic shows the caliper attached to the 220mm wood disc, and then rotated up into position, to determine caliper relocation bracket's design.
The 4th pic shows the caliper relocation bracket.
Last edited by Red Rider; 04-01-2018 at 01:37 AM.
Red Rider's Sand Machine Updated 07/23/14
Now that the guessing game is over, here's the progress pics to date. Most of the work, that has been done so far, involves designing jigs & guides to make the desired symmetrical arcing cuts. Once they're made though, they make the rest of the work somewhat simple.
The 1st pic shows the arcing cuts made by the router. These cuts, recess the disc into adapter plate, so that the front of the disc is flush with the adapter plate.
The 2nd pic shows the jig, with the adapter plate bolted to it. The jig has a pin, located off-center, between all of the bolts, that allow the jig to pivot at the proper radius for the desired cuts.
The 3rd pic shows the Galfer wave rotor bolted to the adapter plate.
Red Rider's Sand Machine Updated 07/23/14
Nice work, Router Master!
Sent from my Z958 using Tapatalk
End mills are for sissy's. Great ingenuity.
85 Tri-z Power valve on Inverts
85 Tri-z Basket Case
01 gsxr750 engine/Tri-z frame (long long way from complete)
Red Rider's Sand Machine Updated 07/23/14
A little more progress the last few days. I came up with a design for the adapters. The design incorporates an alternating short spoke & longer, swept spoke around the circumference, for a total of 6 spokes, which should blend into the wave rotor nicely. The design was sketched on cardboard, then a 1/3 "pie slice" was cut out, and transferred onto 1/8" thick aluminum sheet. This design was then carefully cut out to use as a router guide template. The aluminum template was then bolted to each adapter 3 times, and the design traced all the way around the circumference of the adapters. Once the design was traced onto the adapters, the template was removed, and the design was "roughly" cut out. Once an adapter is roughly cut out, the aluminum guide plate will be bolted onto the adapter once again, and the trimming bit will be installed in the router. This trimming bit has a ball bearing, that rides against the aluminum guide template, thus accurately cutting away the aluminum of the adapter, flush with the guide template.
The 1st pic shows a "roughly" cut adapter.
The 2nd pic shows the aluminum guide template, and an adapter that is 2/3 of the way through the final trimming process.
The 3rd pic shows the aluminum guide template bolted to an adapter, prior to final trimming of the last 2 spokes.
The 4th pic shows a completely trimmed adapter & wave rotor combo.
Now, I need to do the same to the other adapter.
Last edited by Red Rider; 04-04-2018 at 02:36 AM.
Red Rider's Sand Machine Updated 07/23/14
A bit more progress today. Both adapters have been cut out & trimmed down to size with the router. The router has done such a nice job, I decided to round off the outside edges, both front side & back side, as the edges were pretty sharp, after being trimmed down to size with the router. Once again, I used a bit, with a ball-bearing guide. Except this time, the bearing was run against the adapter itself, as there is no need for the aluminum guide template anymore. The 3 mounting holes have been drilled, and I've gotten started on boring out the center hole with, once again, you guessed it, the router. Here's the progress to date.
Red Rider's Sand Machine Updated 07/23/14
Oh HELL YEAH
Sent from my Z958 using Tapatalk
Thank you. Your project would have been a breeze with the method I used. Just drill the holes out in your new piece of aluminum, roughly cut it out, bolt it to your reed valve, then trim it down to the final size by letting the ball-bearing guide bit trace around the outside edge of your reed valve, and you'd have a perfect duplicate of that outside profile.
Red Rider's Sand Machine Updated 07/23/14
Do you have a pic of the cutter you used. Man I haven't used a router sence I was in high school lol
If its on the internet its got to be true they can't put any lie's on the internet
I sure do. It will bring back good memories of your high school days, unless of course you lost a finger in woodshop, or something. Here ya go. From left to right:
Left Bit: 23/32" Flute Straight - Used with a jig to make the arcing cuts in pics#1 & 2 of post #19.
Middle Bit: 1/8" Radius Roundover w/bearing - Used to round the edges in the only pic of post #24.
Right Bit: 1/2" Flush Trim w/bearing - Used with the aluminum template to make the outside profile cuts in the only pic of post #24.
Keep in mind, all of the work done on this, is with the router mounted to a router table, and these are carbide bits.
Last edited by Red Rider; 04-05-2018 at 07:16 PM.
Red Rider's Sand Machine Updated 07/23/14