Slotted/drilled brake rotors any good?

[Pilot]

You see these slotted/drilled brake rotor kits on Ebay, such as the ones found here. Anybody have any experience with these type of rotors? Snake-oil gimmick or...?

[RePete]

They're mostly bling.

My understanding is that cross-drilled rotors (which are at higher risk of cracking) don't improve performance unless you have brake pads that release gases when hot - modern brake pads don't do that. And slotted rotors act like a cheese grater on your pads compared to a smooth rotor which doesn't wear them as fast. Smooth rotors have more braking surface too. I don't think there's any real harm in having either slotted or cross-drilled installed, but no added benefit either.

[CJMR2T]

Dont waste your money....

The only time a rotor that is drilled should be used is if it was designed to be that way from the manufacture. Most of the drilled rotors are just plain old off the shelf rotors that are then drilled. The cracking issue that RePete mentioned is true but its not as bad as many think... Even high quality purposely designed rotors have a tendency to get hairline fractures off of the holes.... Its really dependent of the amount of heat that is induced that can cause the cracking....

Heat is where the whole drilling thing becomes a problem. When you drill a rotor, you remove Mass from the rotor. Any time you remove mass from it, you take away its heat absorbtion and dissapation ability. This causes the rotor to overheat thus causing warping and cracking.

Now many sellers and manufacturs will tell you that when you drill it, you increase the avalible surface area to cool the rotor, which is true but the amount of surface area gained is very minimal and most OEM type rotors do not suffiencently pump air through them thus the gain is surface area has a no real effect on cooling..

Now if a rotor is infact designed to be drilled, it will have two added design features. These two things are thicker disc plate sections and directional curved vains.. The thicker plate sections offers an increase in mass to compensate for the lose due to drilling. The directional curved vain design offers two advantages, one, it pumps air far more effectively then a straight vained rotor and the second benifit is that if offers even more surface area cause a ARC that covers the same straight line distances is longer in true lengh then a straight line and obviously the increase in true/effective length = more surface area.

Slotted rotors on the other hand help clean the pad giving a better bit to the rotor (as long as the rotor is properly bedded). They dont really wear the pad any more then a smooth faced disc. Pad wear is more dependent on the compound of the pad then the type of rotor face be it smooth, slotted, drilled or drilled and slotted.

Proper bedding is where most people mess up when it comes to brakes. Most (including brake techs at shops) either dont know what bedding is and or dont know how to properly do it....

RePete sort had it right with the pads releasing gas when they are hot... This is called Pad Out-gassing and all pads do it. Its just that modern technology in bonding agents has gotten a lot better... A pad is basically a mixture of different materials that are ground up into a powder like substance and mixed together along with a bonding agent (glue) and pured into a mold along with the proper metal backing plate to make the pad... The bonding agents (like everything else) has a point in which it will vaporize thus turning to a gas. The older technology bonding agents had lower vapor points (i.e would vaporize at a lower temp). New (modern day) pads will still Out-gas but it takes a much higher temperature for this to happen.

Brake fad is what happens when a pad out-gas's. An ultra thin layer of gas forms between the pad and the rotor thus prevent the pad from making full contact with the rotor. Because older pads had a tendency to out gas at a much lower temp, fade was a common problem and brake designers came up with the idea of drilling rotors to give more openings and ways for the gas to escape....

So is it worth it to buy drilled rotors? For a street car, 98% of the time, NO, unless you want the "LOOK".....

One thing to note is that it is commonly believed that by drilling or slotting a disc will create tiny edges that will cause the pad to bite into the rotor more thus making it grab better but there is no real world proof to back this claim or theory up. If this were true, race teams would still be using drilled rotors. Now yes, many do use slotted rotors, but this is strickly because of the pad cleaning action of the slot. With a slotted design, there is no noticable lose of mass to the rotor thus retaining its heat absorbtion ability (one of its two main purposes).

I could go on for hours about this and all the pricipals of a brake system, but I'll refrain from it as this is already getting LONG!!!!!!! and Im not a very fast typer....

[YellowJacket]

meh, they are cheap enough to enjoy them... if you want em go for it. I am enjoying mine (TOYOTA MR 2 1985-1986 2 Front Drilled Brake Rotors Cquence Brake Parts).
Its like throwing a boat anchor out the window.


So what is the proper way to bed brakes?

[efx]

Hey, you have an account on that other forum right? The mr2oc one. Here's a thread I added to on that and will hope answer your question. Just have to read the whole thing though but I think you'll find it very informative. It's only two pages long. Just trying to save a re-write.
MR2 Owners Club Message Board™

[YellowJacket]

Originally Posted by efx

Hey, you have an account on that other forum right? The mr2oc one. Here's a thread I added to on that and will hope answer your question. Just have to read the whole thing though but I think you'll find it very informative. It's only two pages long. Just trying to save a re-write.
MR2 Owners Club Message Board™

Ha ha... awesome! I was thinking of that exact thread when I was typing my last post!

[kbrew8991]

Originally Posted by YellowJacket

So what is the proper way to bed brakes

follow the mfg's instructions

if there are none - the general idea is to get the pads good & hot to get a layer of the material to transfer and then keep driving without using the brakes to let things cool nice and evenly

[Pilot]

Lots of good information--thanks everyone--I guess I will pass on the slotted/drilled rotors. How about pads, any particular make have superior results?

[ToyotaTechGeek]

wait.
slotted rotors were originally designed to deal with glazing that occurs with the use of organic pads. the slots 'cut' the glaze off of (organic) pads.

the thing is, most who have the need for drilled rotors wouldn't buy them from an unknown ebay source.

[ToyotaTechGeek]

Originally Posted by Pilot

Lots of good information--thanks everyone--I guess I will pass on the slotted/drilled rotors. How about pads, any particular make have superior results?

this question is going to generate lots of opinionated response. (subjectivity/objectivity).
it's going to depend on the type of driving you plan on doing. you also have to keep a budget in-mind. i've seen some ridiculously priced brake pads on my search for that which i was seeking. why? there's lots of different 'exotic' brake pad compounds out there.

[YellowJacket]

I think if anyone does any deeper research, most long standing ebay sellers like cquence.net are all buying their blanks from centric. Their rotors are PLENTY fine for the street driver and they look cool on top of it. There are NUMEROUS other car forums (GTO for example) where all these guys are buying them and post over post that indicate that they are an extremely good economical option.

If you are talking about track use then maybe all these conversations are more valid, but I dont see how a full set of rotors for about $120 for street use from these companies (either direct or via ebay) can be viewed as anything other than a great deal.

You pick the look you like... smooth, dimples, slots, drilled, etc.. and enjoy them. When they wear out, or warp, etc get some more. This is a disposable item like pads. Re: pads, its known the Porterfield pads are favorite among the track guys. So if you are wanting track/race car performance get them but commuting or daily driving your 2 in a spirited manner those are a splurge. If you have the disposable income, sure, get the best, why not.

[ToyotaTechGeek]

Originally Posted by YellowJacket

I think if anyone does any deeper research, most long standing ebay sellers like cquence.net are all buying their blanks from centric. Their rotors are PLENTY fine for the street driver and they look cool on top of it. There are NUMEROUS other car forums (GTO for example) where all these guys are buying them and post over post that indicate that they are an extremely good economical option.

If you are talking about track use then maybe all these conversations are more valid, but I dont see how a full set of rotors for about $120 for street use from these companies (either direct or via ebay) can be viewed as anything other than a great deal.

You pick the look you like... smooth, dimples, slots, drilled, etc.. and enjoy them. When they wear out, or warp, etc get some more. This is a disposable item like pads. Re: pads, its known the Porterfield pads are favorite among the track guys. So if you are wanting track/race car performance get them but commuting or daily driving your 2 in a spirited manner those are a splurge. If you have the disposable income, sure, get the best, why not.

Originally Posted by ToyotaTechGeek

this question is going to generate lots of opinionated response. (subjectivity/objectivity).
it's going to depend on the type of driving you plan on doing. you also have to keep a budget in-mind. i've seen some ridiculously priced brake pads on my search for that which i was seeking. why? there's lots of different 'exotic' brake pad compounds out there.

thanks for reiterating my point! however, i could NEVER buy/obtain such an important article such as ANY braking component for "the look" i like.

[kbrew8991]

Originally Posted by Pilot

Lots of good information--thanks everyone--I guess I will pass on the slotted/drilled rotors. How about pads, any particular make have superior results?

how do you drive your car typically? Do you do any competition or track stuff with it??

[efx]

My previous post link also talks about the pads. I'm not going to say which are better or worst since there are links for you to also look at and many different types of materials as mentioned by others. You can check the different options for you to choose from. This will also vary depending on your budget and like others said what you like and maybe how you drive. Trust me, every little bit adds up. Sorry about pointing out of this great forum, I just hate typing myself.

Originally Posted by Pilot

Lots of good information--thanks everyone--I guess I will pass on the slotted/drilled rotors. How about pads, any particular make have superior results?

[Pilot]

Originally Posted by kbrew8991

how do you drive your car typically? Do you do any competition or track stuff with it??

The car is pretty much an every-day driver with some sport driving when the opportunity arises. not being used on the track.

[kbrew8991]

Originally Posted by Pilot

The car is pretty much an every-day driver with some sport driving when the opportunity arises. not being used on the track.

I dunno if I'd go with anything all that fancy then - nothing more aggressive than a Porterfield R4S or Hawk HP+ (or similar, say no to EBC though) for sure

[YellowJacket]

Originally Posted by ToyotaTechGeek

thanks for reiterating my point! however, i could NEVER buy/obtain such an important article such as ANY braking component for "the look" i like.

Thats you. But when all those products are good enough for street use, you have that luxury.
Pilot qualified himself as a daily driver...he should buy what he wants with the look he wants, at the price he wants. There is no sense spending money on performance race quality parts for a daily street driver if you are on a budget. The brakes on the mk1 are great with oem stuff. I assure you nothing you can buy that comes from a centric blank that is slotted, drilled, dimpled, etc are any LESS than OEM quality. Any decent ceramic pad will be sufficient.

[ToyotaTechGeek]

Originally Posted by YellowJacket

Thats you. But when all those products are good enough for street use, you have that luxury.
Pilot qualified himself as a daily driver...he should buy what he wants with the look he wants, at the price he wants. There is no sense spending money on performance race quality parts for a daily street driver if you are on a budget. The brakes on the mk1 are great with oem stuff. I assure you nothing you can buy that comes from a centric blank that is slotted, drilled, dimpled, etc are any LESS than OEM quality. Any decent ceramic pad will be sufficient.

ok, dude and your opinion is your own. i guess i've always followed the philosophy of FORM FOLLOWS FUNCTION. i don't agree with the idea that all brake rotor blanks are created alike. no Made In China crap for me, thanks.

[CJMR2T]

Umm, I think he was asking if it was worth it to buy from a performance stand point, not a look stand point.

Yes he can buy whatever he wants, but if looking for better braking performance, then they are a waste cause they will not give you any better braking performance performance over stock with the exception of possibly the pad compound used.... The rotors themselves will not offer an advantage over a stock replacement smooth face disc.

Will they work, yes. Are they worth it, No (unless you want the "LOOK")... But at that same time, there is it saying of "Function Over Form"...... About the best thing to buy if you are staying with stock sized rotors is to buy ones that are Cryo'ed (they'll last A LOT longer then any other rotor of the stock size)...

[CJMR2T]

Damn, you beat me to the "function over form" part.... LOL