Ducati Monster Forum

I've read about this in the Desmo Times book and that machining your rear brake rotor with bigger holes helps the cooling of the rear brake and also shaves unsprung rotational mass.

Has anyone on the forum done this with positive results?  Are the costs of machining at a shop worth it, or are you better off just buying an aftermarket rear wave rotor or something?

Any photos?

What's a rear brake ;D

Standard rule of thumb:

If someone makes it, just buy it. Life will be easier.

http://ducatimonsterforum.org/index.php?topic=32825.0 (http://ducatimonsterforum.org/index.php?topic=32825.0)

I don't think it would be difficult for a machine shop to drill some oversized holes.  I'm not looking to cut the rear rotor into a "wave" pattern, just want to drill some oversized holes into it in an appropriate pattern

Hmm... drill larger holes into an engineered piece of material that has been designed specifically to withstand a rediculous level of force and heat in order to keep you alive....

yeah, you COULD do it... but I wouldn't suggest it. go buy a set that is designed to be that way. 

lets put it this way... would you cut out the air vents on your helmet to provide more airflow?

Sort of what I'm getting at. Who determines appropriate pattern? Size? If they do it wrong, and they may be unaware as to what "right" actually is, you risk having the rotor not perform as it should. That item you want to drill holes in was never intended to see the sort of thing you plan on doing to it.

You can also drill holes in your frame to shave weight. I still wouldn't recommend it.

There are real live, professionally engineered lighter rotors out there. Just buy one-it'll bolt right in.

What he said.  Your rotor is designed and manufactured to perform at its desired spec.  Drilling larger holes would weaken the rotor and potentially (very likely) throw it off balance.  It would also have less surface area to be in contact with the brake pads.  All in all, it's not worth it.  Get better wheels if you are that concerned about unsprung weight. 

I get the point that it "MAY" not be safe or designed for such alterations.  However reading about it and seeing photos of it done in the Desmo Times service manual made me wonder.

That's not a significant concern. There is already PLENTY of contact area in the lightweight, drilled rotors. Excessive amount of contact area in the stock.

Just buy an aftermarket rotor. They are cheap, especially relative to fronts. I've got a motomaster, and its the "flame" wave cut, just because.

I'm telling you that, as a mechanical engineer, it is NOT SAFE. it may still work, but it is NOT SAFE.

??? disagree. as a mechanical engineer.

Sure, They don't come that way, but its not because they "can't".

For another source, try DucPond: They have done TCM lightening, like this: http://www.peterverdonedesigns.com/600RRrearrotor.htm (http://www.peterverdonedesigns.com/600RRrearrotor.htm)

(http://www.peterverdonedesigns.com/images/content/motorcycle/600rr_rear_rotor_mod3.jpg)

(http://www.ducpond.com/images/specialss/Maxdriveway1.jpg)

I remember many years ago reading about a brake shop that would drill or re-drill rotors, drums, and clutch plates.  I think the idea was basically to get an even distribution of open area across the face.  Taking any concentirc ring on a rotor, it should have similar or the same amount of hole area as any other.  They didn't give absolute specifics as to the pattens as that was part of the black magic they get paid for.  Part of the reason was not just more venting but to help break up and get rid of a super heated layer of air that tends to stick near the brake surface and reduce efficiency.  

The magazine that did the article had the drums on a VW bus drilled at the shop and said the braking was notably improved with just a slight hissing sound that hadn't been there before.

That said, buy a lightweight aftermarket rotor if you want light weight and get some aftermarket pads to help it stop better.  My stock rear brake was useless for anything but stabilizing the bike during stops until I got some Ferodo pads.  Now it's actually a functional brake, at least as much as any rear motorcycle brake.

Scott

The way I look at it, the engineers who made the rotor to begin with were given (or came up with) criteria for the rotor.  Most likely acceptable safety margins, performance requirements, max weight, and a price point.  Strength of the material chosen and cost for that material would be considered.  The come up with a basic design (considering cost of manufacture, performance characteristics, etc), figure out the major stress areas, then apply that to a table of materials.  Lifespan is considered at the stress levels to come up with the cheapest material that satisfies that design, and go with it.

Those safety factors are probably large enough that you could modify the rotor to a large degree... but you are sacrificing safety.

At least in my opinion.

You know we're talking about Ducati here right? ;D

That said, I like the ducpond design.  There's also Braking, several different eBay wave designs and I believe EBC used to or still does make a rear.

yup. and i'm not talking retail price... i'm talking cost to manufacture.

now to put on my gear-head hat.... don't you want a nice, shiny, high performance, free-floating brake rotor? :D

Stress is not great on a rear rotor, especially in comparison to front rotors, the surface has to deal with heat but its not incredibly high in comparison to the front

. There's not a lot of considerations for rear brake rotors on Ducatis. The biggest factor comes from the penny-pinchers: We need cheap rear rotors. They are not a substantial part of the sport motorcycle riding experience. This is reflected in the style carrier used, the simple circular shapes and small holes. The design is essentially "XXXmm diameter, thickness of Ymm, 6 bolts".

You think people that work in these aftermarket cnc shops are engineers? I think not.

drill away, its only the rear brake.

(http://images.google.com/url?source=imgres&ct=tbn&q=http://www.orangecountychoppers.com/occ/images/jasonworkstation1_lg.jpg&usg=AFQjCNFUZSflAP9VsV5aiJQWYdMScA4gbw)

You mean to tell me there are actually people on here who use the rear brake?
I think the only time my foot's been on that peddle is at a stop, on a hill!   

I guess you're not doing high enough wheelies??  That rear brake will save you from flipping over.

Ok as an update to this post, I just came back from a local machine shop.  For $20 and 30mins of their time, they had taken some measurements, spun up a CNC program, inputted it into the CNC machine.  Clamped down the rotor and went to town.  The CNC machine was so accurate with the cutting and at the same time the rotor was being sprayed with a white liquid which must help the cutting bit and keeping materials cool.  I had them drill 12 x 1" holes evenly around the rotor.

It came out perfectly, done on the cheap, lighter, and looks bling and its a modded OEM part  [thumbsup]

I'll try to get pics up

Sounds like a deal to me. Let's see them pics.

(http://i3.photobucket.com/albums/y54/TheoAftonomos/DUcati%20S4Rt/DSCN5762.jpg)

 [thumbsup]

Is that a cnc of your original rotor?

Bravo.  That puts to shame all the late night garage drill press work on the Campy Record stuff back in the seventies.   [clap]

Makes me feel old generation old.   I think I'll go oil my Brooks saddle.

Sure is.  Then I went out and did something crazy.   Bought me some surplus Titanium, and had them copy the rotor into that.  Talk about light (and worthless cept for holding the bike on a hill!)  ;D

have you tried different pad types?

Nothing personal, but getting a wheelie that high, you're only losing speed. If you're wheeling on purpose, you should be on a Gixxer, or Buell, but that post was before I realised Squids are also piloting Duc's now and that this was a Squid Site!

Fixed it for you.  [thumbsup]

Does it still count if it's a controlled environment and NOT on public roads?  Or is that extra squidly for the added effort?

Sounds like a pretty conservative stance to me.  :P Odd.

this took a turn towards funny, and fast

Hey guys, what's a Squid? I'm guessing it means a reckless driver/rider?

Anything to do with that shop Calamari Racing? Or do they sell good Greek food besides race bikes?;D

very nice!  [thumbsup]

Very nice.    [thumbsup]

picture as promised

(http://i833.photobucket.com/albums/zz255/samminaudo/Bikeshow2010054.jpg?t=1270699648)

Looks great!

bah...it was cheap and effective. [popcorn]

Where/When did you get your marvics? I'm jealous.

Those are not mine.  It was a borrowed picture for the machine shop.  I've got the heavy brembo's  [puke]

curses. in the same boat.

Anyone have experience with Quality Machining Company in regards to machining the rear rotor for their Ducati (or other bike)?
Quality Machining Company (http://www.qualitymachineco.com/racing.html)
(http://www.qualitymachineco.com/thumbs/GSXR%20Rotors-%20thumbs/tn_03%20rotors%20new%20style.jpg)
I am thinking about this for the Monster...

now that would be different.  [thumbsup]

Don't know Blue.  To me it channels 60's flower power stickers and VWs.  Not that there is anything wrong with that.

Hey man, peace, love and ...

I know what you mean about the pattern.  The photo I posted is one from their website, but not from or for a Ducati.  I emailed the company regarding the pattern they use for Ducatis and I hope to hear back from them soon with a picture to boot! 

Just to pipe in, I come from the motocross world and I'm new to the street side of things. I did take the MSF course, and the rear brake seems very important and is heavily emphasized for slow manoeuvrings and trail braking. In motocross, used it all the time!!

Neh, I'd take that sumpregnant dog off if I wasn't worried about the ugly unused bracket left behind.

But in all seriousness, I only use my rear brake in emergency stopping situations.

i only use mine when starting on a hill and i don't want to be holding the front brake while rolling on the throttle, and holding myself at stoplights.   and leaving big skid marks as i come to the stop sign when i think i can get a good shriek from the tire.


rear brake is useful in gravel, sand, etc - just like the situations when you'd want to ride the bike like a dirtbike - low traction situations.

The MSF teaches to all bike markets, so they emphasize the rear brake - you can't stop a cruiser without it.

reading a signature recently, i began to wonder, what are rimoza parts? [cheeky]

Those parts are made in Nicaragua. 

I disagree about the rear brake. I use it all the time in appropriate conjunction with the fronts when rolling to a stop and when navigating low-traction sections of pavement. Not just because that's what the MSF instructors instructed, but because that's what it's for and it makes sense to me to do it that way. To me, relying on the fronts to do all the stopping amounts to laziness and nothing more.
I like the look of the stock rotors just fine. I don't really like wave-type rotors at all. Lacy rotors don't amount to enough weight savings over the stock engineered rotors to matter. Be smart and get rid of your boat-anchor wheels if you care that much about reducing unsprung weight. I'd rather have the full pad contact area than a bunch of holes. It's the friction between the pads and the metal that stop the bike, not the friction between the pads and air, venting of hot gases be damned. Less steel to absorb the heat of the friction and resultant warpage is also a concern to me.
Lace/wave rotors remind me of tricked-out Busas with stretched swingarms and chrome wheels on cartoonishly wide tires. And I've never seen a GP bike with swissy brake rotors either. I'm just not convinced they work as well. No hard evidence.

i'm all for a nice lightened rotor - the effects of reduced rotational inertia is huge.

i don't think the originally equipped rotors on the ducs are all that great. mind you, i think the pads are worse, but the rotors are short changed in how they float as well as materials.

try some iron rotors out. they have even better feel than the oem ss blend rotors

i'm looking forward to the braketech floating rear rotors coming available. they are lighter than the oem rear rotor and will be better in regards to pad drag. i'm currently running a moto-master flame rear rotor that i got from one of the guys on TOB back in the day. it works for what i use it for, which isn't much.

the harder you are on the brakes, the more weight is shifted forward - pivoting the bike, which means the less you can use the rear brake lest you lock it up - when your rear tire is skimming the ground (there's a GP bike reference) you best be off the rear brake.

Wow, much discussion.
For me, the purpose of having a lighter rear rotor is to decrease the unsprung weight.

Taken from the Carrozzeria website (pertaining to wheels, but rotors fall into the same catagory).
http://www.forged-wheel.com/About.htm (http://www.forged-wheel.com/About.htm)
Sprung weight is everything that suspension holds up, unsprung weight is the wheel, sprocket, caliper, disks, axle and a percentage of the shock and swing arm. Unsprung weight is the nemesis of the suspension in the war to maintain tire contact with the tarmac. The less unsprung weight the more effectively the suspension and ultimately the tires can do their jobs. To explain this lets pretend you had a job in which you had to raise and lower a hammer as moving obstacles came by on some sort of moving conveyor belt. First you had a hammer with a 1 pound head. As the conveyor belt moved faster at some point it would become impossible to move quickly enough and the hammer would be hit be an obstacle. If you used a hammer with a ½ pound head you would be able to negotiate the moving obstacles at a greater speed. Now imagine the hammerhead is the wheel, your wrist is the suspension system and the moving conveyor with obstacles is the bumpy tarmac. This is why most cars have independent suspensions. Reducing unsprung weight will improve the traction especially in bumpy corners.

Rotating weight on a motorcycle counts twice every time you accelerate or brake. The reason for this is the engine must increase both the wheels’ linear velocity as well as their rotational velocity. It is a little more complicated in reality, but each pound you remove from the wheels is equal to approximately 2 or more pounds removed from the chassis. Reducing the weight of you wheels will allow your bike to not only accelerate faster, but brake better as well.

An additional benefit to reducing rotating weight it the reduction in gyro effect of the wheels. The easiest way to understand this is to conduct an experiment at home. Get the front wheel off your bicycle. Hold the axle with your hands and have a partner spin the wheel at a moderate speed. As the wheel spins pretend you are the forks and “turn” the wheel. You now have a feel for gyroscopic forces. Now imagine what a motorcycle wheel with much greater weight and speed goes through when you attempt to change directions quickly in a in a series of turns.

But what if the wave pattern with elongated holes actually keeps the same braking efficiency or increases it?

Taken from the Galfer website.
http://www.galferusa.com/html/faq.html#4 (http://www.galferusa.com/html/faq.html#4)
Why the Wave® pattern?
Admit it! You’re interested in Galfer Wave®s because they look cool!  We like the way they look as well but believe it or not, there is quite  a bit of thought that went into our patented technology. On a normal round  rotor, the leading edge (think toe-in) of the brake pad is in contact  with the entire height of the blade as the pressure is applied. Because  the contact covers the entire height of the blade heat buildup takes much  less time to occur and you end up with heat related problems like brake  fade, thermal lockup, and inconsistent braking performance. What the Wave®  pattern does is take that leading edge of contact between the blade and  pad and constantly move it up and down, thus minimizing heat build up  and its inherent problems. Cool air is also introduced in greater amounts.  In addition, through centrifugal force, any foreign matter is thrown clear  of the outer rim of the blade and doesn't’t get lodged in the pad  material.
and
http://www.galferusa.com/html/faq.html#5 (http://www.galferusa.com/html/faq.html#5)
Do holes in discs help?
Well, it depends what you mean by “help”. Holes in the “blade”  of a disc (the part that the brake pad sweeps over as it is in motion)  will save a bit of weight but contrary to public opinion, they do not  help to cool a braking system. Notice on MotoGP motorcycles and most race  cars, there are no holes on the rotors. There are actually situations  where holes can be detrimental to your braking. In muddy conditions, dirt  gets trapped in these holes and proceeds to chew up pads that, in turn  will chew up rotors because of the constant uneven abrasion between the  pads (which have the dirt imbedded in their surface) and the rotors, which  get gouged to heck by that dirt. If you’ll notice, if there are  holes in a Galfer rotor, they are never round. They are usually oval,  teardrop or cylindrical in shape so that foreign debris is directed away  from the rotor via centrifugal force.

Trouble is, they are all trying to sell you something!
Getting back to machining rotors, yes I do use the rear brake.  Quality Machining says they can remove a pound from the rear rotor.
Here is a picture of a 1098 rear rotor.
(http://i42.photobucket.com/albums/e343/Ducatibomber/photo-2.jpg)
Here is a picture of a Paul Smart rear rotor (would be the same for a DSS Monster).
(http://i42.photobucket.com/albums/e343/Ducatibomber/photo-3.jpg)

The ability to lose a pound of unsprung weight for less than $100!

Oh, the AMA does not allow wave rotors in the rule book, so not that wavy, Swiss cheesy rotors don't work, but that they are not legal for racing (this neither proves or disproves their usefulness).  
At this point for me, I am on the fence.

I'd go for it.

One thing I do not want to do on the Monster is to stupidly lock up the rear brake because I'm used to using it on the dirt bike.  I figured the reduced area of the funny rotor is one way to reduce its effectiveness.  That and less rotating unsprung weight for not much money. 

I'm happy with mine (Braking, like the Galfer)

Beringer, on the other hand, employs round rotors without holes.


I expect to equip a bike with their 4-disc front system in the future, i just happen to like what's on my current ride, so I'll have to grab another bike to do it with!

I just did mine and its about 600 grams now was about a kilo.  I'll weigh my galfer tonight to compaire [bacon]

Cool, I am interested in the numbers.
Who did the machining of the rotor for you?

I had it done through a sponsor who works with a machine shop that also did my flywheel.  So I couldn't tell you.  Its just got alot of holes in it.  the ones on this page look better, but i'm plenty happy with what mine became.  I have an ABM rear as well I can weigh, if I can find it.  It might be in a box burried in my garage that is snowed in. [bacon]

FWIW I have a 6 pot 310 full floating beringer set up on my supermoto race bike and its pure magic.  their masters are so nice, not to mention crash well. [bacon]

wow what a can of worms I opened up here.  Anyways, my rear rotor that was machined looks just like the one in caymans pic.  I had just sold it so I cannot give you any weight values.  I did use if for a while with no issues.  I only sold it for a wave rotor for a good price.  Otherwise I would have kept it.

Ducati stock rear rotor=940g
Lightened one (mine at least)=620grams
Galfer rotor=576g
Vortex rear sprocket=410g  46t 520 for a marvic wheel

so there it is about a pound just with rotor.  I don't know what a stock sprocket weighs, don't have any, but it's gotta be 2x what the vortex does.  you could get even more weight off of the stock sprocket by facing/thinning it. [bacon]

i've got a motomaster on mine - never thought to check its weight.

for those with money, yoyodyne has a Ti rear brake rotor.

Thanks for posting the weights for the rotors.  It is good to know what the advantages to the various options are. 
Man, it has been a long winter; too much time to think about the "what if I did this...".

I have an ABM that I'll weigh this weekend.  I'm looking to sell it after that [bacon]

Here is one that the mech that built my Monster, did on his bike.


(http://i201.photobucket.com/albums/aa91/chiflado/photo2.jpg)

my monster lost nearly 5.5 lbs when I did the rotor, 520 chain and sprocket.   [thumbsup]