Custom Cut OEM Rotors

[rojoracing53]

Here's a little something I haven't done in awhile but I had some free time and no money for buying stainless steel brake line so this was the next best thing

[k-os]

Waterjetted I assume? Looks nice. I'm tempted to do this with a rear rotor from one of my bikes. I've got access to a waterjet at work and making up the CAD file isn't much work.

[cuong-nutz]

Oh looks nice! How much of a weight saving was that?

[rojoracing53]

Originally Posted by k-os

Waterjetted I assume? Looks nice. I'm tempted to do this with a rear rotor from one of my bikes. I've got access to a waterjet at work and making up the CAD file isn't much work.

I wish I had a water-jet this was all end-milled on a plane open table Bridgeport with a cheap CNC retrofit. What worse is I don't have CAD so I do the calculations by hand At least I'm a wiz at trig and calculus(thinks back to highschool "Teacher when will we ever need to know this stuff")

At least now the hard parts done, know I can just pop a new rotor in and hit start.

[rojoracing53]

Originally Posted by cuong-nutz

Oh looks nice! How much of a weight saving was that?

Stock was 1lb 13oz and this one is 1lb even, it was more for looks then anything else.

[k-os]

Originally Posted by rojoracing53

I wish I had a water-jet this was all end-milled on a plane open table Bridgeport with a cheap CNC retrofit. What worse is I don't have CAD so I do the calculations by hand At least I'm a wiz at trig and calculus(thinks back to highschool "Teacher when will we ever need to know this stuff")

At least now the hard parts done, know I can just pop a new rotor in and hit start.

That's awesome. How hard was the cutting of the rotor with a mill? Did you use carbide or just take light cuts with HSS? If you don't mind me asking what did you pay for your Bridgeport setup. I'd love to buy one for hobby use, even though I have access to CNC and anything else at work.

[cuong-nutz]

Originally Posted by rojoracing53

Stock was 1lb 13oz and this one is 1lb even, it was more for looks then anything else.

Would you consider doing more for some extra cash?

[rojoracing53]

Originally Posted by k-os

That's awesome. How hard was the cutting of the rotor with a mill? Did you use carbide or just take light cuts with HSS? If you don't mind me asking what did you pay for your Bridgeport setup. I'd love to buy one for hobby use, even though I have access to CNC and anything else at work.

This is what I have access to at work since our machine shop at work is only for in house repairs to the big machines in the production shop. I think they payed like $30,000 for it but I think it's a total POS and would never buy a retro setup personally but hey if that's all I have to work with I'll still get it done. I'm still learning as I go so I need to refine my feed and spindle speeds as well as depth of cut(never had a teacher, they just asked me one day "can you figure out how to use this thing") It was about 2+ hours of machining with HSS and roached one bit with the roughing pass. How fast do you think you could do this with water? God love with a get to work this aluminum instead of tool steel.

[k-os]

Originally Posted by rojoracing53

This is what I have access to at work since our machine shop at work is only for in house repairs to the big machines in the production shop. I think they payed like $30,000 for it but I think it's a total POS and would never buy a retro setup personally but hey if that's all I have to work with I'll still get it done. I'm still learning as I go so I need to refine my feed and spindle speeds as well as depth of cut(never had a teacher, they just asked me one day "can you figure out how to use this thing") It was about 2+ hours of machining with HSS and roached one bit with the roughing pass. How fast do you think you could do this with water? God love with a get to work this aluminum instead of tool steel.

Water it could probably be cut in 30 minutes would be my guess.

[rojoracing53]

Originally Posted by cuong-nutz

Would you consider doing more for some extra cash?

I wouldn't mind knocking out a few more of these for others if their interested. I used to make them for my own race bikes(Yamaha and Suzuki) as well as for a few other racers. If your a heavy rear brake user then I wouldn't recommend this for your bike though because under extreme loads and heat(dragging into every corner on a track or canyon) the thinner bridges would be more pron to cracking. But if your like me and so many others who don't drag the rear continuiosly you'll be fine. A group order would work best.

[jp129]

Originally Posted by rojoracing53

I wouldn't mind knocking out a few more of these for others if their interested. I used to make them for my own race bikes(Yamaha and Suzuki) as well as for a few other racers. If your a heavy rear brake user then I wouldn't recommend this for your bike though because under extreme loads and heat(dragging into every corner on a track or canyon) the thinner bridges would be more pron to cracking. But if your like me and so many others who don't drag the rear continuiosly you'll be fine. A group order would work best.

I'm sure there will some interest depending on the price point. If you don't mind, would you send me a PM with a ball park figure?

[rojoracing53]

Originally Posted by jp129

I'm sure there will some interest depending on the price point. If you don't mind, would you send me a PM with a ball park figure?

For a single rear rotor how's $70 plus $10 to ship it back to you. If we can get at least 3 rotors in one go then $60 per rotor and $10 per return location(3 rotors return to same address is only $10) let me know what you guys think.

[CZroe]

I can see this being cool for the casual and recreational riders but for the commuters that's gotta wear REAL fast and a new rotor is expensive.

[alex.s]

looks great. i wonder if the rear brake works anymore? LOL

[rojoracing53]

The rear brake works fine there is a certain loss of power from less surface area but I can lock it up just fine, most street bikes including the ninja have overpowered rear brakes to begin with. Racers will adjust or cut there rotors to reduce power so they can lay there foot on it and drag it without locking up the rear entering a turn. If you use your rear brake every time you touch the front then yeah this wouldn't be good for you, I use my clutch as a rear brake and only use my rear brake on occasion when I need it so my wear is almost none existent.

[CZroe]

The laws of physics make it such that the same wear that was distributed over more area will now be applied to the lesser area for the sane amount of stopping power and it will wear faster proportional to the percentage of area removed. For me, this translates into new rotors more than twice as often. As someone who has had to replace a rotor due to wear once already, I would not look forward to the expense.

[rojoracing53]

Used the **** out my rear brakes this weekend hauling ass down Hamilton. I used it to trail into and through the downhill decreasing radius corners. This is not something I've even done or practiced before but it just seemed so natural. I will say it sucked in the right turn because while trailing the brake through the turn a cant have my toe on the peg, if I can't have my toe on the peg I can't get my ass off the seat, if I can't get my ass of the seat I can't get the rest off my body position into an aggressive position, if I can't get into an aggressive body position I feel uncomfortable leaning over that far at those speeds, if I can't lean the bike I look like a retard trying to go fast. Don't look like a retard trying to go fast get a thumb brake instead

I brought this up because I'm currently cutting @mgentz rear rotor and thought I'd measure the different in wear we both have. My rotor is actually .002 thicker then his even after the abuse I put it through on Saturday as well as the occasional use over the last 22k miles. This has quailed an worries I have of needing to replace my rear rotor prematurely from wear. I still think if you need to replace your rear rotor then your using it way more then what is necessary.

If anyone else wants a rotor cut its $70+actual shipping per rotor or $60+actual shipping each for group order of three or more. Group order can be from different locations so long as I get to cut all of them at the same time.

[mgentz]

Glad to hear you finally used yours! See how much it can do for you!

As for your technique...get out and ride dirt bikes more, you'll adapt in no time.

[rojoracing53]

Originally Posted by mgentz

Glad to hear you finally used yours! See how much it can do for you!

As for your technique...get out and ride dirt bikes more, you'll adapt in no time.

Dirt bikes is totally different and as for dirt I'm a damn good racer at that as well. I still won't use my rear for road racing where every corner is predictable. I won't deny the fact that I'm still adapting to this street riding thing and still consider myself a newb when it comes to street experience. But the speeds I ride at that I've found I use the rear brake consistently aren't riden by 99% of Ninjette riders so I still do think its a required action for most riders all the time. But a useful skill none the less when needed to get out of a sticky situation.

I'm going to seriously look into a thumb brake so if I can use that to further adapt the rear into my style. Plus it'll give me another mod for my bike

[mgentz]

Sweet on both accounts. I use the rear whether it be dirt, motard or street. Road or track. It is a tool for fine adjustment on a street/track bike. But I'll be honest I don't brake much on a track with the 250.

Glad to see the rotor in. Thanks again for an awesome mod!

[choneofakind]

Jason, did you just wake up one day and say, "I think I'll race a Yamaha in AMA today." ??



I know your story since we PM'd about that, but I don't get it how someone in your position can still be considered a "noob".

I always drag a little rear brake on the MTB on the tight fast stuff because it helps rotate around a little, or I use it to trim speed a little on the road bike. But for some reason, I never use it on the ninja. I'll try using it to trim speed next time I'm out. (In like 2 months )

[CZroe]

Originally Posted by rojoracing53

...
I brought this up because I'm currently cutting @mgentz rear rotor and thought I'd measure the different in wear we both have. My rotor is actually .002 thicker then his even after the abuse I put it through on Saturday as well as the occasional use over the last 22k miles. This has quailed an worries I have of needing to replace my rear rotor prematurely from wear. I still think if you need to replace your rear rotor then your using it way more then what is necessary.

The wear that caused me to replace my rear brake rotor was abnormal (concentric circles of varying depth; not the service limit), so I agree.

[choneofakind]

How do you get concentric circles on something that rotates about a fixed axis?

[mgentz]

Internet,

I have no doubts that Jason is a better rider than me. I am simply saying that having another tool in your box is a good thing. The rear can be your friend street or track and knowing how to use it with finesse is invaluable.

Jason is also in no manner a noob.

[Jiggles]

Cut me!

[rojoracing53]

Originally Posted by choneofakind

Jason, did you just wake up one day and say, "I think I'll race a Yamaha in AMA today." ??



I know your story since we PM'd about that, but I don't get it how someone in your position can still be considered a "noob".

I always drag a little rear brake on the MTB on the tight fast stuff because it helps rotate around a little, or I use it to trim speed a little on the road bike. But for some reason, I never use it on the ninja. I'll try using it to trim speed next time I'm out. (In like 2 months )

I wanted a motorcycle since I first learned to ride a bicycle as a kid. But my family just never had the money and as a kid I even less outward enthusiasm then I do these days so maybe my parents didn't know I wanted one. At 14 got my first Moto(ysr50) and one year later started racing in the mini leagues. From there I just picked it up so fast we went up a bike size every year till I was a professional 4 years later racing in Europe. I'm still faster on a 50cc street bike then anyone I've ever had a chance to race against and this is also why I don't race it much, no competition=lack of fun

Using the rear on a Mtb is similar to a Dirtbike and nothing like a street bike. When I do solo 24hr Mtb races I have plenty of laps to perfect the course and I do so by placing challenges on grouped sections of turns or an entire trail section. The challenges will include not using a gear shorter then I specify forcing me the good faster up hill, no dabbing(touching you feet to the ground or rocks), and my personal favorite seeing how far through a section of high speed turns can I get without touching ether brake. This last challenge requires a lot of attention to detail(trail conditions, traction, suspension) and memory. I have to predict the bind corners before I can see them and plan my angle of attack based on the bikes traction and suspensions reaction I experience on the previous lap. So after riding for 20 hrs strait and completing around 15 ten mile laps my lap times are still close to the same because I have become efficient at saving energy by using the brakes as little as possible.

When I was using the rear yesterday at first it was out of reaction to the sudden increase in riding speed. When first I noticed I was using the rear I notices it was a reaction of fear and doubt of the roads condition and lack of knowledge to the bikes reaction at those speeds on that road. This is when I try changing a reaction born out of weakness into a strength. I'm still skeptical on wether on not useing the rear was an asset yesterday, think it was more a crutch supporting my own lack of confidence with the traction since the road were often dirty. If I had more confidence i would have not used the rear brake so much and simply leaned into the corners more thus going faster but I probably would have crashed in some hidde gravle doing so.

I believe if your seriously analyzing your street riding to this extent then your simply being unnecessarily analytical and or riding to fast for the street. You it for the track then by all means analyze away

[choneofakind]

Originally Posted by rojoracing53

I believe if your seriously analyzing your street riding to this extent then your simply being unnecessarily analytical and or riding to fast for the street. You it for the track then by all means analyze away

No, I'm just wondering for my own purposes since I try to do my learning and stupid mistakes on the MTB and I was wondering about how the rear brake would transfer.

I've only been to the track once. I have plans for this summer with csmith12 again. (and Jiggles if he makes good on his promise to show up) Other than that, I ride cautiously on street.

[rojoracing53]

Originally Posted by choneofakind

No, I'm just wondering for my own purposes since I try to do my learning and stupid mistakes on the MTB and I was wondering about how the rear brake would transfer.

I've only been to the track once. I have plans for this summer with csmith12 again. (and Jiggles if he makes good on his promise to show up) Other than that, I ride cautiously on street.

I'm sure if jiggles can steer clear of any Toyotas along the way he'll be just fine

[choneofakind]

You coming along too? June 21 and 22 at Mid-Ohio

[old3]

Have you tried anything with a front rotor?

[rojoracing53]

Originally Posted by old3

Have you tried anything with a front rotor?

You mean like removing material like I do the rear?

[CZroe]

Originally Posted by choneofakind

How do you get concentric circles on something that rotates about a fixed axis?

Joking?

con·cen·tric
[kuhn-sen-trik] Show IPA
adjective
having a common center, as circles or spheres.

The center is shared, but the diameter of each circle is different, meaning the larger outer rings contain the smaller inner rings.

Instead of wearing down flat all the way around, the thickness of my old rotor varied from the inside to the outside. If you pinched the center-most portion and slid your fingers across as you pulled away, you would feel a distinct wave with many lands and valleys. If you pinched it and spun the tire letting your fingers slide while holding them at the same distance from the center, you would not feel the thickness vary at all. New brake pads would only contact the high portions until conforming to this wave shape (no longer flat).

[rojoracing53]

Originally Posted by CZroe

Joking?

con·cen·tric
[kuhn-sen-trik] Show IPA
adjective
having a common center, as circles or spheres.

The center is shared, but the diameter of each circle is different, meaning the larger outer rings contain the smaller inner rings.

Instead of wearing down flat all the way around, the thickness of my old rotor varied from the inside to the outside. If you pinched the center-most portion and slid your fingers across as you pulled away, you would feel a distinct wave with many lands and valleys. If you pinched it and spun the tire letting your fingers slide while holding them at the same distance from the center, you would not feel the thickness vary at all. New brake pads would only contact the high portions until conforming to this wave shape (no longer flat).

You could have had them turned but chances are they were warped as well like the front rotors do and I don't know how that would work in a turn machine. I personally wouldn't care to much about what you describe because that's a performance issue more then integrity I believe, and like I say the rear brake is overpowered as it is.

[CZroe]

Originally Posted by rojoracing53

You could have had them turned but chances are they were warped as well like the front rotors do and I don't know how that would work in a turn machine. I personally wouldn't care to much about what you describe because that's a performance issue more then integrity I believe, and like I say the rear brake is overpowered as it is.

Well, the motorcycle shops made a big deal about it and it was pretty exaggerated and drastically different from the front rotor. I don't doubt that the deep rings were well past the service limit due to abnormal wear. It even looked shiny and polished compared to the normal texture of all the other rotors I have.

[rojoracing53]

Originally Posted by CZroe

Well, the motorcycle shops made a big deal about it and it was pretty exaggerated and drastically different from the front rotor. I don't doubt that the deep rings were well past the service limit due to abnormal wear. It even looked shiny and polished compared to the normal texture of all the other rotors I have.

Did they determine the cause of the problem? Sounds like uneven wear caused by overcooking and glazing the pads and rotor then continuing to use it over time.

[choneofakind]

Originally Posted by CZroe

Joking?

con·cen·tric

No, sorry. Fingers engaged before brain. Happens all the time when I post while doing HW

[CZroe]

Originally Posted by choneofakind

No, sorry. Fingers engaged before brain. Happens all the time when I post while doing HW

Happened to me earlier doing work-work.

[CZroe]

Originally Posted by rojoracing53

Did they determine the cause of the problem? Sounds like uneven wear caused by overcooking and glazing the pads and rotor then continuing to use it over time.

Nope. I replaced it all my self and it didn't come back. It could have been a few things, first, I think they drag even when I wasn't using them, which would explain why those pads unexpectedly wore out first even when I did the vast majority of my stopping on the front (there are a few other reports of this happening to people who swear they don't use it at all). Second, I was only routinely checking the front because I fully expected those to need replacement first, so the rear wore completely away. I touched it in tandem with the front and heard a grinding noise from the rear so I let off and replaced them immediately. That's when I went with EBC in the rear. Third, I wanted the better pads in the front when those wore out, so I moved the EBC pads up and replaced them in the rear with cheap and abnormally thick "Sixity" brand pads (from eBay). It wasn't until about 30K miles and at least one more brake job that this wear became apparent in the rear and it was getting worse fast. I was over 30K miles.

I'm pretty sure that the overcooking/glazing was a result of the uneven wear. It was more surface area and sandwiched heat.

[old3]

Originally Posted by old3

Have you tried anything with a front rotor?

Like a bit of cutting and a conversion to a floating rotor???

[rojoracing53]

Originally Posted by old3

Like a bit of cutting and a conversion to a floating rotor???

I did swap on an R6 front wheel and R1 rotor with brembo full floating buttons. The time and effort to do the same by modding the Ninjette's OEM components would just be a waste of time for an inferior end result. You'd never want to slot a front rotor becuase you'd lose braking power and that's never a good thing in the front.