Just what the title says. I've heard that the drilled rotors are bad b/c it acts as sand paper.

I've seen rotors with slots only and rotors drilled only. I've also seen rotors with both. Which is better? I've always wanted to know.

 

here's my basic understanding. Slotting don't dissipate heat as well as cross-drilled (or both combined), but they wear better, especially for most street use. I would only recommend cross-drilled / slotted if you're actually having problems with brake fade. But my cross-drilled / slotted rotors have held up very nicely so far. They are brembos.''

I think there's a nice tech article around here...I'll try and find it.

 

http://www.protegeclub.com/forum/sho...threadid=17195

 

thanks ya sir

if you have more info., it will be appreciated.

 

it's a bit much to read... there is a link to super honda tech (or whatever), where there is some good info, though I didn't read past the first page on that.

 

Actually slotted were designed to allow a better more efficient escape for carbonized vapor over drilled, which is were fade comes from...but they never performed as well as claimed...

"through" drilled (holes all the way through the rotor) had advantages in racing becuase they allowed a large surface area with a relatively less mass, which allowed them to heat up fast so the race pads would bite effectively. The holes allowed an escape for the latter metioned crap and helped reduce fade...But on the street they were mostly married to non racing pads that hated being heated significantly...In which the reduced mass actually made them fade faster than solid discs, the holes only help so much and once the heat threshold is significantly exceeded so much pad material burns so fast that it just builds up even in the holes and creates the same fade...

Fire polished cross drilled rotors ridded the sharp edge that cut pad life in half but they still eat pads faster than flat rotors...

IMO cross drilled rotors are useless for the street...You don't want the type of race pads that need to be heated significantly in order to work properly for street driving (and these are the pads that take advantage of lower specific heat capacity of the low mass rotors), or you will constantly loose arguments with the back of SUVs...With stock pads or "cold" pads, the drilled discs heat up faster than high mass rotors and don't help with fade enough to make it worth it...The same basically applys for slotted rotors...

You can easily keep fade at bay with a good set of performance pads, and as far as the rotors they are mostly aesthetics these days...

 

yeah, i also recommend good tires, and bleeding the brakes with some good quality replacement fluid. SS lines are a nice (genuine) improvment, too.

 

Few more points about drilled/slotted rotors...

1) One of the other reasons that slots/holes were originally used is to alleviate "out-gassing", which occurs when hot gas is released from the pad at very high temperatures, then gets trapped between the rotor and the pad. The holes or slots create a path for the gas to escape. The catch is that modern high-performance brake pads will not outgas until they reach EXTREMELY high temperatures, higher temps than the melting point of a cast iron brake rotor!

2) Contrary to popular belief, drilled or slotted rotors usually run HOTTER than solid rotors due to the less heat-absorbing rotor mass. Yes, they have more heat-dissipating surface area, but in most street applications, this is not enough to offset the lost mass.

3) Drilling holes in a brake rotor inherently weakens the rotor, causing stress cracks around the holes and occasionally leading to catastrophic rotor failure during heavy braking. Slotted rotors have not demonstrated the same failure tendency as drilled rotors, but they will still occasionally demonstrate problems. Whenever this is brought up, some smartass will usually bring up two points: (a) “If they fail, why do Porsche, Mercedes and Saab offer them from the factory”, and (b) “If they fail, won’t the manufacturers get sued?” To address these two points: (a) Porsche, Mercedes and Saab cast the rotors with the holes and/or slots already in the casting, then just clean them up. This process weakens the rotor a LOT less than drilling or slotting an ordinary solid rotor, which is how >95% of aftermarket rotors are made. (b) Yes, we live in a lawsuit-happy society, but sometimes a company can continually hold back the lawsuits with clever manipulation of scientific tests and statistics, even when numerous people are dying due to a faulty design. If you doubt this, do a Google search for “Beech Bonanza V-tail failure.”

Personally, I don't trust drilled or slotted rotors, but you can decide for yourself.

 

Well I was looking for advice because I want to get a big brake kit for my Nissan. It's putting out some pretty big numbers, but are riding on stock brakes.

FastBrakes has a kit with slotted and drilled rotors as an option. So, I guess it isn't necssary to get it. I'm not going to be doing 140mph anytime this century...lol

 

Whoa! Thanks Psuedo. Best link EVAR..

 

According to Road and Track this is partly incorrect...In a "Technical Correspondance" question a reader asked which was weaker...Rotors cast with holes or "drilled" rotors.

The Editor stated that both are nearly identical in strength, the weakness comes from the rotor material lost, not the way it was lost...They also stated that the reason big manufacturers (such as an OE supplier for Porsche etc...) use the cast method is simply that they can create more drilled rotors in a shorter amount of time and with less cost...Smaller aftermarket companies simply drill the holes with machines becuase of the expense to set up the machining equipment and lathes, and with the drilled rotor upgrade being a fairly small and controversial corner of the automotive aftermarket...It is most likely a good call, and why 95% of aftermarket braked rotors are litterly "drilled"...

That was from an issue a few months ago...I am not sure on how valid the Editor's call on the rotor strength is but it seems familiar from Chemistry classes...

 

****....that was the most confusing thing that I've ever read. I thought I had something. Time to re-read...lol

Edit: Aahh, finally. Thanks for the great link.

 

God that was a long thread. Still it leaves me with a couple of questions. Why are the big multi-piston calipers good? Is it because they allow you to have a bigger brake pad which keeps the pads cooler, or is it because they allow you to have more refined control of the force on the rotor for more control on the amount of braking. The standard answer of more stopping power doesn't make sense since much smaller brakes already have enough power to lock the tires on dry pavement.