haha27

i was just wondering if it would be worth cross drilling my new rotors on my iroc? i have had very bad brakes till now with this car now everything is new and i thought about drilling my rotors on my spare time. but was woundering if it would be worth it

Guest

Why would you want to do that? Drilling holes reduces the surface area for heat transfer and I can assure you will affect the braking distance. If you dont have a rotor overheating issue (and I'm sure you dont), dont need to do it.

NINÅ

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customblackbird

iTrader: (15)

i had cross drilled and slotted rotors i got from JC whitney for like 140$ they are stock replacements but are slotted and drilled. i had it coupled with SSBC force 10 aluminum dual piston calipers (about 30% increase in clamping pressure over stock caliper) and SSBC ceramic hipo pads and my car would not stop. i always had bad brakes... i replaced everything and nothing fixed it. i just took the motor out etc and ran all new lines (made by me) and tested it with new slotted and diamond "dimpled" rotors/ceramic pads i got from summit. i got the crossdrilled and slotted rotors mostly for looks and they were cheap and i needed new rotors soo i gave them a try. i just took them off after like 3yrs and the inner surface of each front rotor has worn completely flat (no slotting left its completely smooth) but the outside wasnt worn as much, the SSBC ceramic pads had 50% or more life on them... this tells me that not enough heat was generated and the rotors were too soft for the pads.

the cross drilled rotors are really only needed if your doing fast breaking constantly and in quick bursts from TRIPLE digit speeds.... where the rotor would build up significant heat. the cross drilling holes would drop brake temps like 200 degrees. down side is the rotor doesnt build enough heat on the street, and your brakes wont grip as much. disk brakes need heat to work properly... hence why in the morning its harder to stop when the brakes are cold. also downside for cross drilling rotors is that they actually weaken the rotor and the rotor usually will crack from the holes. this can destroy the car, and the brakes.

slotted rotors are better for street driving, helps vent gases/brake dust but will still build heat. also is the new "slotted and Dimpled rotors" they are basically a mix of the cross drilled rotors and slotted. the dimpled surface looks like diamond shaped caverns cut from the rotor surface between the slots... in the same arrangment as the cross drilling. this will not weaken the rotor but will cool the rotor similarly as well as vent the gases and brake dust more efficently than just the slotting.

http://lib.store.yahoo.net/lib/musta...ackedrotor.jpg

this is what i just stuck on mine.

http://store.summitracing.com/partde...5&autoview=sku

alloy

iTrader: (16)

Here is info directly from Wilwood's web site. Read it and make your own decision.

http://www.wilwood.com/Centers/Infor...ges/faqs_8.asp


Q: What's the difference between slotted and drilled/slotted rotors? Which rotor will be best for my application?
A:

Slots or grooves in rotor faces are partly a carryover from the days of asbestos pads. Asbestos and other organic pads were prone to "glazing" and the slots tended to help "scrape or de-glaze" them. . Also, cross-drilling and/or slotting the rotor for racing purposes was beneficial by providing a way to expel the gasses created when the bonding agents employed to manufacture the pads began to break down at extreme temperatures. This condition is often referred to as "outgassing.” When it does occur, the driver still has a good firm brake pedal, but a significant reduction in friction. Normally this only happens at temperatures witnessed in racing. However, with today’s race pad technology, “outgassing” is no longer a concern with pads designed for racing.

So in the final analysis, drilling and slotting rotors has become popular in street applications for their pure aesthetic value. Wilwood provides rotors slotted, drilled or plain. For most performance applications, slotted is the preferred choice. With certain pad material, slotting can help wipe away debris from between the pad and rotor as well as increasing the coefficient of friction between the rotor and the pad. A drilled rotor provides the same type of benefit, but is more susceptible to cracking under severe usage; however, for street and occasional light duty track use, they will work fine. For more severe applications, we recommend slotted rotors.

91interceptorZ

iTrader: (3)

K I have a question to continue off his original question....I road race and auto cross my camaro...and have cross-drilled and slotted rotors on front (I've had the rotors glowing red hot with bad brake fade, so I do need them on mine), but on the rear I don't...I have just the regular rotors.....I have ordered a brake bias controller to increase some more power to the rear brakes....now the rear brakes are pretty small (pad size), would mine heat up too much like the front used too and fade out?? If so, can you drill yourself the rotors....I have no problem buying some if I need to...but always will save a dollar if I can???

customblackbird

iTrader: (15)

i would not drill the rotors yourself unless u have done so before and have the necessary equipment... its not as easy as just taking a drill bit and drill to them. the edges are beveled. etc.

your rotors are glowing hot? and u have cross drilled and slotted rotors? theres not much u can do beyond that... i would upgrade your pads tho... and maybe bigger brakes. the rotors are gona glow no matter what... that due to the friciton ur applying with the pads and the driving conditions. your not gona get better cooling that a cross drilled and slotted rotor.

here are the things u can do.

easiest would be to get BETTER pad compounds.... more of a racing pad... HAWKS got race pads...im sure wildwood and baer have them as well. they will resist brake fade and be able to increase bite at glowing hot temps... this would be the easiest and prob cheapest thing u could do. try the RED STUFF pads. this will however affect street driving. and u will prob go through rotors faster.

next thing would be to upgrade your brakes... to larger brakes. do an LS1 swap or a C5 vette swap or if u got the $$ go for baer etc. larger brakes with slotted/ cross drilled rotors will not heat as much and will increase clamping. i would try the red stuff pads first just to see how it works... before you have to start spending $$ on upgraded brakes.

dont worry about the rear brakes... i have the SSBC adjustable prop valve for my rears... still they dont get hot enough... they only do about 20% of the braking. but if your worried i would put some upgraded ceramic pads to help with BITE/heat control.

91interceptorZ

iTrader: (3)

yeah, I have the green stuff pads, and do want to upgrade to a baer or wilwood system whenever I get the money (those kits are spendy)...but I didn't know about the ls1 conversion...i'll have to check it out. Yeah, my front brakes have been on fire before (stock rotors), but I race very little drag racing, mostly road course and auto cross, so i'm off and on brakes hard and a lot....and the factory rotors are small as you know...so I upgraded the calipers and to a crossdrilled and slotted rotor...but the rear brakes on my car don't work that well....I have had problems flat spotting front brakes, but rears never lock up...even when car is up on lift, you put it in drive, and you have to press on brake pretty hard to get rears to stop spinning...Now all my rear components are brand new as well, and installed correctly (i'm ASE certified)...but I would like to increase the rear power to help stop me... I just don't want to put to much brake to rear and over heat rear disc....I didn't know though if I needed aftermarket rotors or not.....is the ls1 conversion for front only or all four??? thanks for your help.. and sorry haha27, I don't mean to steal your thread..

customblackbird

iTrader: (15)

u can swap out a 4th gen rear and it will have 4th gen rear disks onit already. they are larger than ours. basically like the newer PBRs.

and adjustable proportioning valve will help alot witht he rear brakes u can increase the rears pressure considerably to increase clamping force. i would keep the stock rear rotors for now and put better more aggressive pads on them with the adjustable proportioning valve. then put a Tee for the front brakes with heavier duty pads like the RED STUFF. and see how it helps in the auto racing etc. depending onhow hard u drive etc ur prob gona have to upgrade at some point. the stock stuff is weak but its ok for most ppl.

i upgraded my calipers to SSBC force 10 twin piston aluminum calipers. 30% more clamping force than stock. but uses stock size rotors. its an upgrade for what i want to do with it. i dont autoX etc. i drive hard but not all the time.

91interceptorZ

iTrader: (3)

I am going to try the adj. prop. valve....so you just take out you stock valve, put the new one on the rear line, and then tee the front, right?? what about the switch in the factory prop valve....that's a brake pressure light switch right?? I going to order the new pads and The calipers you have too....thanks

NatesZ/28

What about some ducting? New pads are great, but if theres no airflow there, youre going to saturate everything with heat no matter what. You might want to also look at a lighter weight wheel to reduce your rotational mass and cool the brakes easier (some nice track only Bogarts or something) along with maybe a track only tire for the road courses and auto-X. I see a lot of guys using foglight openings for air intakes...they'd be great for ducting to the front brakes. Thats the trade off with our ground effects, we have very little airflow under the car where it needs to be. You also might want to look at how to get the heat AWAY from your wheels (header wrap and or ceramic coating on your pipes)

When the car is in the pits, if you have the time between races, put the car on stands and take the wheels off, everything cools down faster

Nate

haha27

hey thanks for all the great info guys i was thnking about doing it mostly for the looks and a little better performance but for no more than what i am doing i think i will keep it stock

racing geek

iTrader: (5)

Yes, upgrading the pads may help give you a little more bite at higher temperatures, but the added friction from these pads will also increase the rotors temperature faster.

The first thing I would try is fabbing up some duct work to send some cool air over the rotor near the caliper. That will probably be the best bang for your buck and have a large impact on braking performance. Just check the rules to make sure it is legal for the classes you compete in.

The next upgrade to try would be a larger diameter rotor. This is where you will also see a huge improvement. The larger rotor moves the caliper away from the hub which increases its torque on the rotor resulting in better braking. A larger diameter rotor also means there is more material to absorb the heat from braking. Drilling the rotors takes away material and therefor hurts the rotors ability to hold heat. This is why I'm strongly against drilled rotors. Yes, some may claim that they aid in cooling, but the only time drilling the rotors really shows somewhat of an improvement is when you also have cool air blowing over the rotor. However, there is also the fact that drilled rotors are easier the crack. Some companies try to counter this by chamfering the edges of the hole to relieve some of the stress, but if you must have drilled rotors, it is best to give the edges of the holes a radius.

The larger caliper will allow for a larger pad surface area which will allow for greater friction with the rotor. I wouldn't worry too much about this yet. You need to focus on cooling off your rotors.

Glowing rotors are not ideal for any form of racing. It doesn't matter what you're doing, if you have glowing rotors, you have major issues with your braking system.

When it comes time to upgrade your braking components, try to steer clear clear of Wilwood, Bear and all those other companies. Wilwood for example uses a lot of GM parts and etches their name on it and calls it a day. You will get the same results by going with a setup from a C5/C6 corvette at probably close to half the cost. Only down side is that you won't have the name of the aftermarket company plastered all over your brakes.

I'll post again tomorrow with more info on why drilled rotors are bad, but it is time for me to catch some Zzzz.

Mike

customblackbird

iTrader: (15)

oh i meant to say to make some brake ducting... sry... i agree. cooling the rotors will help. most racing cars have ducting... its simple. esp on camaros. u can get the 2-3" flex ducting for cheap. i just dont kno how ur gona force the air into the brakes.... maybe coming from the back of the rim shooting the air in from the back... idk. worth a try.

pontiacivan

iTrader: (2)

I'm guessing the hardest part would be getting even, concentric holes, otherwise it might not look so good. I thought if I ever tried this I would get an old spidle and mount it to my drill press somehow. Then I would put the rotor on (with bearings) and drill the first hole. You would then be able to rotate 180 degress and drill the next,then go to 90, 45, 27.5, etc. Once the first "ring" was done you would need to position the spindle so you could drill the next circle of holes....and the next...and the next...oh, yeah there's another rotor to do. Wait....how much are they are ready done. LOL. You could also stagger each "ring" of holes to get a spiral type pattern, just dont space them too close or the rotor will be weakened as mentioned by others. There's probaly even an engineering reason that the holes shouldn't be directly accross from each other to begin with. In fact the liability here is probably not worth doing it yourself. Picture the local prosecuting attorney eating you up over a minor fender bender turned lawsuit... "So you took your drill and made holes in your brakes?" I'm guessing a jury of twelve might not have the technical knowledge to see it your way. Why can't 1LE brakes be easier to find and install?

91interceptorZ

iTrader: (3)

To answer some of your guys post (and thanks for response)....the cross drilled rotor REALLY help my car....what I was saying about glowing rotors is I was on the brakes so much, that the rotors never had any time to cool...and I had really bad fade...now with the crossdrilled ones, it probably cut the fade at least in half....but it's a really good idea about the brake ducting...I was over at a buddy's house last night (he has a lingenfelter corvette with killer brakes), and he showed me on his vette a factory brake cooling duct that was on his car...anyway he has a spare set..so I'm going to attach those to my car... At some point I am going to upgrade to larger rotors, but money is tight right now.....and those kits are exensive..
pontiacivan....thanks for response...as far as 1LE brakes goes....I already have them on the car (B4C camaro)....they are only a little bigger than stock ones, but do help....

89-bird

I would never ever drill or slot a stock rotor they are to thin for it . If you compare the rotor thickness from the vents to out side of a stock rotor and a drilled/slotted rotor the drilled/slotted rotors are thicker to keep them structurly sound and not break or crack on you .

91interceptorZ

iTrader: (3)

not going too....going to buy rotors drilled and slotted or just slotted.......it's a road race car and getting a solid stock type rotor red hot can also crack them.....I just need to really upgrade everything..

pontiacivan

iTrader: (2)

91interceptorZ: I was wondering what direction the air flows from those corvette ducts? Does it blow (flow) at the vents squarely or does it blow at an angle across the disc surface. I think air cooling ( I can handle that mod I think) plus some good aftermarket rotors and pad upgrade would be enough to make me happy.
madmax: Just as an aside, from the braking systems point of view, cross drilling probably doesn't reduce the surface area for cooling. It likely increases the amount of surface for the air to flow across/through depending on the size of the holes of course. From the pads perspective the swept area is technically less,which would increase the heat, but the math is weird because the rotors are spinning. (think of a spinning fan, there's lots of free space in between the blades, but your finger would never know it.)
The information provided by Alloy from Wilwood is logical and likely hard to debate since they are a major player,but skips one important point: It's probably cheaper to slot a rotor from a manufacturing standpoint than to drill it. (the cutting tool only needs to move in or out like a record needle while the rotor turns slightly,creating an arc in one motion per slot, versus down\up, turn, down\up, turn,etc. for the drill.) The slot IS likely to be less prone to fracture than holes though. As far as "outgassing" goes, there's still heated air between the pad and the rotor that needs releasing, even if it's not from the pads bonding agent. Aftermarket suppliers are trusted manufacturers of quality products, but they still have bottom lines and warranty\liability concerns etc.
Just some thoughts\opinions no offense intented to anybody. Physics is way too complicated!

91interceptorZ

iTrader: (3)

pontiacivan....i'll take a picture if I can get my camera to work....I'll have to take a closer look at the too....get back to ya....

Guest

It reduces the surface area for pad-rotor contact, which in turn reduces the amount of heat that is transferred to the rotor and pad, which in turn increases the braking distance by some factor. I already know what the effects of crossdrilling a factory rotor are, you can search my username and crossdrilled and see what you find. Those rotors are still on the car FYI, still look like they did way back when. So much for conspiracy theories, IMO.

There are a lot more dynamics going on with brakes than most people (even manufacturers) take into account. They'll concentrate entirely on one issue, and ignore the other. The brake rotor itself has 2 basic purposes. Ignore one or the other to any degree, forget design and just throw a chunk of metal at the car.
1. Accept heat.
2. Dissipate heat.

The intended use will directly affect the design, if its all done like it should be.

The original poster is probably complaining about a single stop braking distance issue, so crossdrilling is going to increase that distance with nothing else changed. They may be able to use different pads to improve braking performance, but it might more likely be a mechanical issue such as air in the lines, or old brake hoses expanding under fluid pressure.

The other poster, ducts are probably the best idea to try. I have a factory brake setup on another car that is known to be a problem child for warping rotors mostly from excessive heat, so I ran ducts and the problem vanished. Again, the entire system and use need to be taken into account to resolve whatever the problem may be.

racing geek

iTrader: (5)

Ok I'm back and ready to get at it again...

Like I said in my previous post, the bigger the rotor the better. This is why some motorcycles, like the one pictured below, mount the caliper to the inside of the rotor. This allows the rotor to gain those few extra inches in diameter which allow more braking torque which help stop the vehicle in a shorter distance. In fact, the motorcycle pictured below even has an 8-piston caliper to aid in stopping power.


Now lets talk about how much surface area you're taking away from the rotor by cross drilling it... Just guessing (because I don't have any around to measure) lets say each hole in the rotor is a 1/4" in diameter. The area for that single circle rounds to 0.05 in^2. Now for a rotor with a relatively small amount of holes like the one on the left, that amounts to 3.6 in^2 of lost surface area. For the rotor with a lot of holes like the one on the right, you lose 9.6 in^2 (a little larger then your average post-it-note) of surface area. If you multiply those numbers by the thickness of each side of the rotor (which for stock I'm guessing is close to 3/8") then for the rotor on the left, you lose 1.35 in^3 of rotor volume, and you lose 3.6 in^3 of volume for the rotor on the right. This is why drilling is really only used to reduce the weight of the rotor. Even then, you will only be saving 0.35 pounds for the rotor on the left and only 0.93 pounds for the rotor on the right. Just for the sake of numbers and math, lets say each rotor is 11" in diameter. That means that each rotor will weigh around 17 pounds if it is made from cast iron which is the norm for stock and replacement brake rotors. Using these numbers, the rotor on the left only saved 2% of its original weight by being drilled and the rotor on the right only saved 5.5% of its original weight by being drilled. Now if you try claiming that it is rotational mass and that is actually greater then the weight of a sprung item you are correct... in a sense. It operates on a 1:3 principle. Every 1 pound of rotational mass is equal to about 3 pounds of sprung weight. So in a sense, the rotor on the left is like taking 1 pound off the car, and the rotor on the right is like taking 2.8 pounds off the car. (All of those numbers are per rotor)
left and right

If you are still insisting on drilling your own rotors to save a buck, then you should look at the link below. However, he did that for the rotors on his motorcycle which are not vented. When drilling on vented rotors, you need to make sure you don't drill through the veins of the rotor. If you do, you might as well buy new rotors and start over because that is the main structure of the rotor. When you remove that and drive aggressively with it, the extra heat will cause it to fail far sooner then the standard non drilled rotor would have and there will be a lot more damage then you ever expected. Anyway, here is the link.

racing geek

iTrader: (5)

Continuing from the above post...

Brake ducts are often the best way to cool the entire brake system of a car. For example, in 1997 GM used 3" brake ducting to route cool air from the front of a Corvette to the rotor and temperatures were reduced by 33% and braking distances were greatly improved. Gains like that can be seen because the cool air not only cools the rotor, but it also cools the caliper and to some degree even the brake fluid in the caliper. For those wondering about the ideal angle of the ducting, it is slightly downward towards the center of the rotor so the air flows through the veins (vents) and out the rotor.

Brake ducts only only, and should only be needed on that race track. This is because the energy required to stop the car increases as the sqaure of vehicle speed increases. This is why automotive brakes have to work twice as hard to stop the car from 85mph as opposed to 60mph. This is what braking from 120mph requires 4 times the energy that braking from 60mph would. As we all know, that energy is transfered into heat and now we can all see how fast that heat can build up on a road course where speeds are easily over 100mph.

Here is a dust shield on a thirdgen camaro that was custom made to allow the use of brake ducting.


Here is a Mazda setup for road course racing that uses brake ducting. You can see in this picture that mounting something like this in the car is very simple. All you really need is a sturdy bracket by the caliper/rotor and a sturdy bracket near the front of the vehicle. The rest can be held in place with zip ties.


Now I can't seem to find pictures, but I remember reading about a C4 Corvette a guy built for road racing that even had fans inline with the brake ducts to pull air into the rotors even while cruising down pit lane after the race or during slow corners on track. Here is a link to a place that sells those fans.

Mike

91interceptorZ

iTrader: (3)

boy you do like engineering....I couldn't get the links to work....

91interceptorZ

iTrader: (3)

are you saying that on a full out road course car that I still shouldn't use the cross-drilled rotors....I have not added the brake cooling ducts (will do asap)...but a smooth rotor (when I had them on car) last for a lap or so before they fade out so much I can't stop (video show rotors glowing red)....no when I went to the cross-drilled, I always can stop, rotors still get hot of course, but not glowing red.

racing geek

iTrader: (5)

Yeah I'm fixing them atm.

Guest

Eductaion time again on cross drilled rotors I see.

Chris (Madmax) has already stated the physics proportion of the equation and I fully agree not becuase this is opinion, but rather becasue he states facts. More mass equals more heat acceptace and disapation.

So why cross drilled rotors? People have scrubbed that off as ssomething just for looks-NOPE.

What does drilling rotors do?

Two things

1) It decreases rotation mass

2) makes for a better pad initial bite onto the rotor when brake force is applied- its all about braek pedal feel and chassis control. Drilling rotors can be used as a tool for driving comfort and control- or at least thats what I have done with it over the years successfully.

So lets now go back to #1, decresses rotor mass and how this can be beneficial? Well it is only beneficial if you go to a LARGER diameter rotor and want the aid of leverage for stopping power BUT you want the lightness of a smaller diameter rotor. THink of this basically as taking a 12" rotor and streaching it with holes in it to form a 13" rotor- Make sense? it should and it does. Your rotation mass will still centrifically be a little higher due to polar extremities of the rotor mass being now 6 1/2" from center rather than 6" onthe same mass, but unsprung weight is the same, AND lastly but most importantly your brake leverage in stopping power has improved. This has to be done proportionately of course front to rear, or reset in brake bias of fluid delivery.

Now to #2, initial pad bite. As the rotor spins inside the caliper between the pads, velocity promotes air flow and that air flow causes a cushion that will often take a pad more time and pressure to get an initial bite onto the rotor for braking force. Some of you ever driving on actual race pad compounds will know this actually happens alone with just different brake pad compounds never the less the air cushion going with them. The harder, higher working temp, and longer lasting the pad material is, the longer it accept heat. If you get cold street/race light duty pads it generally takes some time to warm up to get that initial bite. Well, drilled rotors will make a pad "not float" as much due to the driled holes alleviating air cushions between the pad and rotor, hence a bit more heat retained from pad to rotor contact and a quicker initial bite.

Thats my theory and I'm stickin' to it (pun intended)

my brakes-yes they were drilled, but they were also massive. However, the entire assemvlies were much lighter that factory smaller ones.

moral of the story- This is an example where drilled rotors were beneficial. It all depends on what you are trying to accomplish.

Dean

Guest

Oh yeah, as for the fun factor...

The curved slots on the SRP rotors I ran from Wilwood make the most bad **** 'whirling down' noise when pulling those bad boys down to a stop nex to a GT3 Porsche at a stop light.....ask me how I know

his head flipped back over his left should so quick seeing what was winding down radiacally to stop next to him-- Took him a second looking in shock as he then commented, "thats not stock is it" with a big smile following. We both left the light mutually in respect and both driving like we were crusing- he had no idea he'd clean my *** in acceleration. Oh I had fun with this car.

Guest

There are rotors out there that:
Have the holes cast into a portion of the vanes.
Dont have vanes, but rather multiple pillars.

Unless you're shearing off the entire friction surface of the rotor, drilling into a vane isnt going to do much harm unless you remove way too much material. I did a calculation quite a while ago and there is a lot more material both in the rotor (just the vanes connection area) and the hub than is physically necessary. General engineering practice calls for a factor of safety of 2, the factory 10.5 rotors on our cars are somewhere around 5+ IIRC.

customblackbird

iTrader: (15)

stock rotors can be grounded down i think like .030 but they are diff for each manufacture... its a cheap alternative to buying new rotors... and just get them resurfaced. i wouldnt get my rotors turned but some do. so they are def thicker than they have to be.

vetruck... whats the part number for those rotors? i just want to see this "curved slot"

these are the brakes i just stuck on mine... they were cross drilled and slotted. diamond slots will not weaken the rotor or allow cracking etc but still vent the gasses and cool the rotor just as effectively.

https://www.thirdgen.org/forums/atta...427altered.jpg

Guest

12 bolt mount 12.90"x 1.25" SRP rotors, aluminum hats, custom Aluminum Global West G-body hubs (Yes I said G-body, not F-body made for a 4000lb roadrace car.)

SRP rotor # 160-7172 and 160-7173
http://www.wilwood.com/Products/002-...-SRP/index.asp

Mounted under a FACTORY 16" IROC rims with a 6 piston radial mount caliper. I have enough room to go to a 13.06 GT rotor easily by adding two shims to the radial mounting of the caliper if I ever wanted to see extended heavy road course use. I choose the SRP's for lighter weight street use- to- medium duty track.

iansane

iTrader: (1)

Wow.

Do NOT drill factory rotors.

Read the comments from Speedtoys and Jon A in this thread.
http://www.frrax.com/rrforum/index.php?showtopic=10173

Guest

Wow.

Why not? Dont see a single thing in that link says not to nor supports it with actual experience. I've already done it, 7 years ago. Still waiting for them to crack and fall off the car like everyone said they will. I guess riding the brakes until they glow a few times just to make sure wasnt enough abuse. Maybe I should ride them all the time and see if they'll split in two then.

iansane

iTrader: (1)

That thread wasn't to show you shouldn't drill your own rotors, that thread was to show that there are times and places for drilled rotors. Did you even read it?

How did you drill your rotors? Do you have equipment that you can set up a rotor and symmetrically drill holes equidistant across the surface without causing stress points? And do you think the typically type of poster on TGO has the same equipment? I didn't think I had to preface that post with, "If you have the equipment, such as working at a high end machine shop, then this shouldn't apply to you because you should be smart enough to know it's possibility."

And I call bullshat on "glowing rotors". You'd be lucky to even stop on stock brakes if they're glowing, let alone have them last 7 years. But whatever you say!

customblackbird

iTrader: (15)

i dont even use brakes... i just downshift

Guest

So, which is it? Do NOT drill them why? Again, neither your reply nor that entire post you linked says not to drill factory rotors or for that matter why. And yes I read the entire thing Mom.

And you can keep your

iansane

iTrader: (1)

I meant "shouldn't" in that first quote, sorry.

Okay. I didn't realize I had to explain the point I was trying to make. Let me break this down for you. I was implying that unless you have the proper equipment, don't ****ing touch your rotors with anything sharp. You'd be an imbecile to attempt cutting any material off if you're not doing it in a completely uniform pattern. Is that hard for you to understand? How did you drill your rotors?

So again, I say that thread is some info on the benefits and downfalls of properly drilled discs. Do not try drilling them at home without a proper setup. Okay? Get it now?

Guest

I used a 3 axis mill. Its pretty simple to get everything in a circle. Leave the bearings in and use something like a centering cone or anything remotely close that will serve that purpose. Most people do not have the proper equipment like what you'd have if you did brake jobs all day long so its best to leave the bearings in place. Then you just touch the cutting bit to the rotor face and turn the rotor (another reason to leave the bearings in) and you have a "perfect" circle. Then just divide it up, and drill away. Honestly the procedure itself was not difficult.

As for the rest now that you explained it all, I agree. You should be using something to keep your rotor reasonably symmetrical but if its not perfect it will not be the end of the world. The mass of the holes are so little, the change in the moment of inertia will be relatively small. I figure by my experiment that each hole is less than half the weight of the smallest point of accuracy of a decent grade tire balance machine (just had tires balanced a couple hours ago, so I checked out the machine) and they're at a smaller radius than the tire so a mass imbalance will have much less effect on the mass moment of inertia. Ideally, yes you want the mass removed equal. Using a hand drill on a rotor with the tire off, yea... bad idea. Put the sharp object down and step away.

iansane

iTrader: (1)

Now that we're on the same page...

Back to the regularly scheduled thread.