Topic: Rotor Drill Pattern for the front Brake Disk - Help me decide

[HedNut]

Looking for a little help/advice/push from my fellow SOHC'rs as to which drill pattern to apply to the rotor of my PROJECT CHAOS K8'....take a peek and vote for one of the choices...let's see how this goes!  Cheers! And thank you all in advance!!



I'll try adding another picture...maybe a little clearer.

[ieism]

Rabid Spectrum probabably looks best on your bike IMO.

[Laminar]

Swirl McHoly!!



Awesome thread, BTW.

[MaaseyRacer]

Less is more.  I would go for simplicity.  The more basic of your designs work.

[Rosinante]

I expect I will be unpopular for the following, but oh well.........

I race cars.  You will virtually never see drilled rotors on a race car.  Drilled rotors are for posers.  It reduces the friction surface.  Reduces braking power.  I'm not making judgements about motorcycling.  I'm just returning to biking after thirty years away.  You guys understand biking better than I.  Perhaps drilled rotors are important for bikes, for some reason.  Improved braking with a dripping-wet rotor, for example.  I'm only reporting what I know from automobiles.  All serious automobile racers use non-drilled rotors.

If a drilled rotor is necessary, auto racers use a rotor that is fabricated with the holes already in the rotor.  In other words, the last thing they will do is take a regular rotor and place it on a drill press.  When this happens, stress fractures will appear around the drill holes after heat cycling.  Real, high-performance slotted and "drilled" rotors are manufactured using a process that shapes and treats the holes properly so stress fractures do not appear.  You do NOT want a rotor coming apart during hard braking.

Again, my experience is not with bikes.  I believe the braking forces of an automobile are quite different, so perhaps my experience and observations are inappropriate here.

[sangyo soichiro]

Seems like all the modern sport bikes have holes in the rotors.

Anyway, I like the bio-screemsicle the best.  Looks like a pattern that'd have to be CNC'd though.  I doubt it's the best as far as functionality, but it looks the coolest, and that's all that matters.   

[eurban]

I agree with Rosinante that braking performance will likely not be improved with drilled rotors.  Reasons to do it?  Aesthetics are certainly one if that's what you like.  Regardless of what people may want to believe this is probably the only "benefit" to the drilled rotors in Hednut's sampler.   Reducing unsprung mass is another.  I have a set of "significantly" drilled rotors on my 750 with a dual disc GL1000 front and the drilled rotors save 1/3 of the weight from a stock one.  These old stainless steel rotors are quite heavy and the weight saved does improve suspension performance and handling.  Given that the stock SOHC single disc setup struggles to stop the bikes effectively, I don't think I would go with "significantly" drilled rotor on a stock setup.  Compression power to surface area "ratio" is just not up to it.  The rotors that Hednut pictured above should loose only a minimum amount of surface so I doubt there would be much ill effect.  Holes would need to be properly chamfered.  I haven't experienced or heard of any issues with the typical thick and heavy SOHC stainless steel rotor having any structural problems with drilling.  My swiss cheese GL set has held up pretty well for 5 years of hard use.  BTW, braking performance is pretty good from this dinosaur setup and admittedly I like the looks too . . .

[754]

When we;
 start using cast ventilated rotors.

 start using a swept area approaching modern bikes, as opposed to double the width.

 start slowing down 800 plus pounds per rotor, as opposed to 300


 When cars run stainless rotors.

 Then , and onlt then, we will start worrying what the cars do.
 ...........................................................................

 Dude, re making up your mind... If you cant make a choice, I cant help you.. cuz if I pick one, and you change your mind (or can make your own decision) later, then it would look like my fault...

[buffalogt750]

Simple pattern not overdone on my 550. Doesn't lose a lot of surface area but keeps pads clean and lets water out.

[camelman]

Turbo Syndicator all the way!  It is totally celestial (it looks like the Milky Way).  ;-)

Drilled rotors are great.  I rode in the rain the other day and totally gave up on my non-drilled front brake.  It was completely worthless until it dried off, and then it transitioned to full power WAY too quickly.  When I have a little more cash, I'm going the same route.

By the way, the holes really shouldn't decrease braking performance.  The clamping force applied by the brake pads doesn't change, and the materials haven't changed (which determine your coefficient of friction), and friction = normal force * coefficient of friction.  In other words, you are going to love them, and be able to stop in the rain.  ;-)

Camelman

[HedNut]

Right on!

Rosinante...this is good Information here!...and i totally agree.  

I'm simply doing this for the cool factor.

There is virtually no performance gains from drilling rotors...aside from the unsprung weight-loss, and a good "out" for water and dirt between the pads. (rally racers benefit from this the most)  
Cross drilling weakens the disk, and believe it or not creates a hotter disk...as metal transfers and dissipates heat much better than air does....opposed to what many folk believe... you get hot-spots around each hole... but probably unnoticeable to the road travelling type...  More-so in the race world.

Sport bikes with drilled holes, well...those holy rotors are designed to handle the needs of that bike...and look cool doing it.   The few ounces you cut from the weight help out on slightly the track too I suppose.  

This is great...thanks all! and keep it coming!!

Buffalog...I like the looks of yours!

Eurban... that GL set-up is slick! And good to hear it performs well also!

754...come on...gimme your favourite.

Camelman...Good to hear a wet' benefit from drilling! And I agree with negligible loss in braking performance.

In all honesty the choices have been all over the place (in my build too)...so I'll probably pick my favourite in the end anyways.  But since I posted this I changed my mind 3 times.... So It's good stuff!!  I really appreciate all the comments and info!!!

Thanks!
 
Cheers!

[Don R]

Has anyone seen a honda stainless rotor crack?

[swellguy]

How much money are you going to be throwing at this anyways?

[754]

I like eurbans, , CENTRIFUGAL, AND SWIRL McHOLY..

[KB02]

Man, I LOVE Apocalyptic Gyration!!! That looks awesome. Would be a pain in the but to drill and makes me wonder if there are too many holes. But MAN it looks cool!!

[Tom in Newcastle......Ontario]

Rabid Spectrum Dialysis...........similar to what's on my 550

[Rosinante]

I appreciate the discussion and information.  I did a little more reading last night, and learned about the tendency for stainless rotors to work less effectively than automotive rotors, particularly when wet.  That in mind, drilling rotors makes more sense.  Still, and even in light of the ligher demands on these (motorcycle) rotors, I would still have some concern about heat checking and cracking at the edges of the drill holes.  It sounds like drilling might make good sense performance-wise (particularly here in the soggy PNW), but I would just keep an eye on the edges of those drill holes.  And I would definitely chamfer the edges, of course.

Again, I appreciate learning.  I am readying a 1978 CB750K after 30 years away from motorcycles, so I am hungry for information.  I am curious about comments here that the brakes on that bike might not be as effective as we would like.  Thirty years ago, I was riding a 1975 CB750K, and according to my recollection those brakes were ferocious.  Perhaps my recollection is hazy.  That shouldn't surprise anyone who knows my lifestyle choices in the interim.

[flybox1]

...... the tendency for stainless rotors to work less effectively than automotive rotors, particularly when wet.  

drilled, chamfered, and resurfaced.
One of the first things i got done on my 350F!
and yeah...its wet up here alright.  i had a crotch/seat full of the white powdery stuff about 2030 last night!!!   FK. happened on my way home.... first time for everything i guess.  


come on Turbo Syndicator!!!!!!!!!

[bistromath]

I appreciate the discussion and information.  I did a little more reading last night, and learned about the tendency for stainless rotors to work less effectively than automotive rotors, particularly when wet.  That in mind, drilling rotors makes more sense.  Still, and even in light of the ligher demands on these (motorcycle) rotors, I would still have some concern about heat checking and cracking at the edges of the drill holes.  It sounds like drilling might make good sense performance-wise (particularly here in the soggy PNW), but I would just keep an eye on the edges of those drill holes.  And I would definitely chamfer the edges, of course.

Again, I appreciate learning.  I am readying a 1978 CB750K after 30 years away from motorcycles, so I am hungry for information.  I am curious about comments here that the brakes on that bike might not be as effective as we would like.  Thirty years ago, I was riding a 1975 CB750K, and according to my recollection those brakes were ferocious.  Perhaps my recollection is hazy.  That shouldn't surprise anyone who knows my lifestyle choices in the interim.

In 1969, those brakes were revolutionary. Compared to a modern sportbike, it's like trying to stop the Queen Elizabeth II with a canoe paddle.

[HedNut]

Awesome guys! Thanks and keep it coming! ahah  Stopping the Queen Elizabeth II with a paddle eh! hahah  That's good stuff.

Swellguy...how much money do I plan on throwing at this?...HOPEFULLY just the cost of some good cobalt drill bits maybe some ATF for cutting fluid....set my speed and pressures right...and giver' in the G-rage on my $80 Canadian Tire table top drill press.....  here's hoping!  (yeah...I think the bio disks are out for that set-up!)

Cheers!
 

[cb650]

I like the swirl.  Put one on a yami swirl wheel and make people dizzy.

[dusterdude]

I agree with Rosinante that braking performance will likely not be improved with drilled rotors.  Reasons to do it?  Aesthetics are certainly one if that's what you like.  Regardless of what people may want to believe this is probably the only "benefit" to the drilled rotors in Hednut's sampler.   Reducing unsprung mass is another.  I have a set of "significantly" drilled rotors on my 750 with a dual disc GL1000 front and the drilled rotors save 1/3 of the weight from a stock one.  These old stainless steel rotors are quite heavy and the weight saved does improve suspension performance and handling.  Given that the stock SOHC single disc setup struggles to stop the bikes effectively, I don't think I would go with "significantly" drilled rotor on a stock setup.  Compression power to surface area "ratio" is just not up to it.  The rotors that Hednut pictured above should loose only a minimum amount of surface so I doubt there would be much ill effect.  Holes would need to be properly chamfered.  I haven't experienced or heard of any issues with the typical thick and heavy SOHC stainless steel rotor having any structural problems with drilling.  My swiss cheese GL set has held up pretty well for 5 years of hard use.  BTW, braking performance is pretty good from this dinosaur setup and admittedly I like the looks too . . .

sorry for the hijack guys,eric,can you send me a pic of your gauge mounting?thanks

[HondaNorway]

Can someone tell me where I find cad files of drilled rotors? Or maybe real scale pictures. I tried searching.. 

-Stian 

[Tom in Newcastle......Ontario]

http://forums.sohc4.net/index.php?topic=45389.0



Try here...........

[HondaNorway]

http://forums.sohc4.net/index.php?topic=45389.0



Try here...........

Thanks