speedjunky

iTrader: (1)

I found a killer hook up on rotors $240 buys a full 4 piece set front and back.Go to WWW.PERRY@ MASTERGRADE.NET

lemond

link doesn't work

Dvst8

iTrader: (6)

um....is it an email or a web link? haha

OC_

iv read so much stuff that says x-drilled rotors does nothing but shorten the life of the rotor... unless you want good looks...

SonicRaT

iTrader: (6)

I don't understand there benefits, don't you want MORE friction, thus more surface area for brakes, why make it less? I don't quite understand to be honest.

Ni5mo180SX

LOL

M5150

the reason you wait it is for heat dissapation and also deglazing

BlackRx7

I thought the x drilling was about heat disapation, the less heat the better braking right?

ponykiller

not all brakes are better at lower temps. Some are designed for high temp operation, while others are for low temp operation. Either way, there can be too much heat, so you must still keep them cool. Too low a temp, and the brakes are also not efficient, so you must keep them in the operating temp range.

CarmonColvin

Cross drilled rotors to many things.

1. They weigh less because there is less material in them. It might sound marginal but it could be as much as 3 lbs per rotor that is a significant amount if you are worried about unsprung weight (that matters in a suspension setup when determining the proper spring rate). (BTW: in IT racing it is popular to take brand new rotors and have them turned down to their minimum width to shave pounds of material off of them. This is not safe for daily driving but is safe if you are inspecting them after each race and replacing them once or twice a season.)

2. They disipate heat better because there is more surface area for air to pass over/through them.

3. They give a place for the brake pads to gas out to. Some break pads give off a gas when hot and under breaking. On a solid rotor the pads can actually float on a pocket of gas and not actually touch the rotors (on in extreme heat and breaking will this happen). Slotted rotors will also keep this from happening.

4. They keep the pads from sliding on break dust. Some pads at the right temperature will dust so bad it is like having graphite between the pads and rotors (cheap pads will do this).

On the down side they are prone to cracking between the holes through heavy heat cycles. Some of the HIGH DOLLAR rotors have the holes cast into them instead of drilled after the rotors are cast. These are less likely to crack but are hella expensive and probably not even available for our cars.

I think F1 used to use rotors that had the holes cast into them but now I think all teams use solid carbon fiber rotors. I can only imagine they cost in the thousands of dollars EACH.

TristanTII

Cross drilling was originally done to allow degassing. Old break pads would release gasses, reducing their effieintcy when hot, the cross drilling was to give those gasses somewhere to go. New break pads don't have that problem, so all the holes do is look good, and reduce the amount of rotor mass, which leads to higher temps, and shorter rotor life.

Slotting rotors does seem to help somewhat, keeping the pads from wearing unevenly, and helps with glazing problems. But they still probably reduce pad life, especially if the slots are too deep.

I plan on going with solid rotors, possible cryo treated. Don't know how much it costs yet.

RETed

http://fc3s-pro.com/TECH/MODS/BRAKES/rotors.htm

Heat dissipation due to more surface area is bullshit.&nbsp Removing metal decreases the rotor's ability as a heat sink.&nbsp If you surpass the heat capacity of the rotor, the heat goes ELSEWHERE (i.e. pads, calipers, etc.).

The ONLY reason to drill them is unsprung weight.&nbsp 99.44% of the people in here can't tell the difference between drill or non-drilled rotors on the track - me included.

Bottom line, cross-drilling is a waste of time and a waste of money.&nbsp It should not be used on a street car, period.

The full Grassroots Motorsports write-up is shown on the MR-2 page with a link included on the above URL on my webpage.



-Ted

Ni5mo180SX

Why is heat dissipation due to more surface area bs?

RETed

I've seen arguments along the same lines.&nbsp The heat capacity of the rotor is a lot more important that the increased surface area.&nbsp Therefore, the increased surface area is moot, if you're decreasing heat capacity.&nbsp Ask any of the race car engineers why they do or do not run cross-drilled rotors, and #1 reason "for" is reduced weight - NONE of them bring up the point of increased surface area for increased cooling.

If you study how most race cars are designed for brake cooling, you'll notice that the airflow is ducted into the CENTER of the hub.&nbsp The airflow hits the backside of the rotor/hub and the airflow starts to move radially (due to the rotating "fins") on the vented rotor.&nbsp The brake ducting is thus flowing from the inside radially in these brake cooling systems.&nbsp They really do NOT blow through the brake rotors perpendicularly; think about it - the rotor is spinning at a very high rate, and you're trying to force air through them???

A race car standing hard on the brakes can turn the rotors from ambient to over 1000F in a matter of seconds.&nbsp Heat capacity is a better thing at this point that increase surface area...



-Ted

DC350

What about on bikes? Just for looks?

how about slotted rotors?!

RETed

I can't comment on bikes - I don't have direct experience with them myself.

The full GRM article is posted.&nbsp Go argue with them...


-Ted

Funklord

according to that website, it looks like they're $400 and for an s2000? is that right?

CarmonColvin

After more reading I have to agree so ignore "2. They disipate heat better because there is more surface area for air to pass over/through them. " in my last post.

I have read it both ways now but the smaller heat capacity had more research and proof behind it.

Just goes to show you "Don't belive everything you read on here"..

BTW: My car has slotted rotors all the way around.

Thanks Ted.

RETed

Sorry if I sounded a bit agitated back there.&nbsp I've got tons of things going on, and it seems like I'm being bombarded from almost every side of my life - I don't want to get into a detailed description right now.

I'm a bit tired of arguing the increased-surface-area theory.&nbsp GRM did a great write-up on the whole mess, and their audience would be more appropriate to the readership in here.

Thanks for being more cordial about the whole thread.


-Ted

eljefe62

Now what about slotted?
I was under the impression that slots would transfer heat out to the edges of the rotor, thus making heat dissipation easier.

RETed

No, the slots are there to "wipe" the brake pads to keep them "clean".&nbsp Slots have nothing to do with more cooling - same situation with the cross drilled.


-Ted

junior-coyote

I have heard that at first (50s 60s?) brake rotors were drilled primarily for outgasing (venting gas generated by hot brake pads.) Newer brake pads gas much less, so you don't really need the holes. But, they were originally trick, and some people still like them.