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Discussion Starter #1
Not too long ago, I went to a break and suspension seminar... The subject of cross-drilled rotors came up - turns out that they were originally developed to allow the gasses (that were expelled from the pads when they were heated) to escape which elimiated pockets of air between the pad and the rotor under heavy breaking (cross-drilling has nothing to do with cooling down the rotors). Break pads of today do not gas like the pads of yesteryear, so why cross drill the rotors in the Elise?

Is it for looks? For weight (can't be saving much there)? Does the Elise have some of exotic break pad?

Just curious. ;)
 

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I assumed it was for marketing reasons as cross-drilled look cool.

But weight may be an issue. It's unsprung weight...so it is very important.

Nothing else makes sense to me. Outgassing? Water? Hello? I have not had a problem with non-cross-drilled rotors ever.

I find that nothing causes more debate that brakes on a car. :)

These things really change/improve braking.

Pad material
Contact area
Fluid type (for boiling and moisture resistance)
Cooling
Better tires (because it is the final limiting factor)
BIAS from front to back
Heat shedding
Making the car lighter
Not using them so much :)
 

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I looked up the issue on the web, and found a page here (http://www.shotimes.com/brakes/part2.html) that tries to sum it up. How accurate is it?

Making some mere observations, the N.A. M3 does not have cross drilled rotors, but the Euro version does. The Euro version performs slightly better and weights less, but it is not necessarly due to the fact they are cross drilled. A more interesting observation, is that the Ferrari 360 has cross-drilled rotors, while the Challenge version (race version) of the same car has solid rotors. Aston Martin uses slotted rotors, apparently to clean the surface of the pad.
 

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Discussion Starter #4
One thing that wasn't mentioned is that there is a big difference between the holes being cast into the rotor as opposed to being drilled into the rotor. Cast cross-drilling is much stronger than just drilling the holes yourself... I would be *very* surprised if Lotus just drilled the rotors as opposed to having them cast that way. I would be willing to venture that we will not see too many cracked rotors on our Elises due to the holes in the rotors..
 

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> more interesting observation, is that the Ferrari 360
>has cross-drilled rotors, while the Challenge version
>(race version) of the same car has solid rotors.

That isn't so, the Stradale has cross-drilled rotors. See TopGear magazine, July 2003 p. 40.

Cross drilled and/or slotted rotors are phenomenal. They give a car more "bite" and better heat dissipation. Not at all a marketing-only design feature. (Have you ever seen a modern sportbike with *non* cross-drilled rotors?)

Thomas
 

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I thought the biggest reason was for heat dissipation.

Cross-drilled rotors provide larger surface area=greater area to spread heat=less chance of brake fade=happy track driver.
 

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Everything with brakes is a compromise. More heat shedding. Less clamping surface area.
 

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You are both right...

In theory you have less surface area, but in reality you really don't for a coulple of reasons. #1, pads (even modern pads) do outgas when they are hot, which keeps your pads from contacting the rotor 100%. The cross drilling and/or slots do away with that problem. #2, the pads "flex" into the holes just a wee bit as they pass them, which gives them more bite (and a very lovely "whirring" sound).

If you have faulty castings and/or cr*ppy machining, combined with heat cycling, you can break the rotors. With quality castings and quality machining, this really isn't a problem if you aren't planning on doing the 24 Hours of Daytona or similar.

I've run cross drilled and slotted rotors an all of my cars for nearly the past 10 years, including autocrossing and nasty caustic Wisconsin-Salt-Slush-Winters(tm) without so much as a hairline crack in any of my rotors. They work, and they work well (urban legends notwithstanding).

The downside is that they tend to create more brake dust than non-cross-drilled and/or slotted rotors.

Thomas
 

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Oops, almost forgot... the other downside is that you have less metal to dump heat into... think of the rotor as a "heat capacitor", the more mass that you have in the rotor, the more heat that they will absorb without overheating.

But, the amount of metal removed in a cross-drilled brake is really only grams, not enough to make a significant impact for most of us mere mortals.

Thomas
 

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If they are good enough for a $215,000 Ferrari, who am I to say that they aren't good enough for our $38,500 Lotus?

Isn't it pleasing when we can compare our beloved Elise to a top notch Ferrari?

(And, off the record, if the price were the same I'd have to take the Stradale over the Elise... but I would have to paint over that awful stripe on the hood.)

:)

Thomas
 
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Nicky Hayden is the man but Rossi is a god

Rossi just rides those brakes to (try) and make it fair. I always root for Nicky Hayden to win but no one can ride a MotoGP bike like Rossi.

But serriously I believe that the front brakes on a MotGP bike are Carbon Fiber. Carbon Fiber stops pretty good with out fancy holes.

I'm a big Yamaha fan (very happy to se a Yamaha head in an Elise) so I'm holding my breath to see Rossi sign with them for next year. Thenmaybe we'll see something besides "big Red" on the box.
 

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You got me there... :rolleyes:

... but carbon brakes work better when they are hotter, so putting holes in them would defeat the purpose (and make them weaker).

Thomas
 

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if you want better stopping power get braided hoses, Pagid pads, and sticky rubber :)

note to self, try to remember that americans will think of contraception if you mention rubber....
 

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Can't stress the importance of a quality rotor with cast drillings. I was at a HPDE at LimeRock Park CT this summer. An Audi TT with cross drilled rotors lost a wheel at high speed. The rotor basically disintegrated taking with it the caliper and then the wheel. Metal pieces all over the track, very scary. Slots are apparently fine as long as the slot does not carry all the way to the edge. Apparently a fracture line can develop if the slot traverses the length of the rotor. I'm sure a good quality rotor is the key factor no matter slots, dimples, diamonds or drilling.
 

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If someone wants to give me that car, I believe that I can live with the stripe. Incorporated the colors of the Italian flag, which works for me. Does look rather like a giant penis, though.
 

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Thomas,

1)When I said "Challenge", I did mean "Challenge". The Stradale is a different model.

2) Yes, I have had cross drilled rotors crack on me before. And I'm not the only one. Push the envelope and it will happen.

3) Carbon fiber brakes do work better once they are warmed up, but they certainly don't work better as they become hotter. That is to say, they have a minimum operating temperature and a max.
 
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