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Discussion Starter #1
What is the fed spec Elise getting for brakes?
Are we getting the aluminum/silicon matrix pad rotor combo as the S1 SE got or are we down graded to cast iron rotors?

If we do get the good stuff, are the Aftermarket providing suitable pad material to go with those special rotors?

I believe the pad material will have to be formulated to be compatible with the rotor material.(transference of pad matrix to rotor surface for retardation ability as opposed to good ol' friction)
m.
 

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The MMC rotors were phased out quite some time ago, problems with not having effective braking in all conditions as I recall. I think all the S2s are fitted with iron rotors.
Chris
 

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I was told that those brakes were not good in wet conditions because there was no place for water to escape during braking if enough water is on the rotor. Could lead to potential disaster.
 

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MW, that doesn't make much sense...no place for water to go? I imagine it'd be comparable to a typical vented rotor in that respect...I'm not sure how water could affect the rotor, other than providing excessive cooling.

As for the switch from MMC rotors, I think I read in one of my Lotus books that the change was necessary due to inavailability of MMC rotors (the supplier went out of business, I believe).
 

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Matt,

When I was at the track in England, I saw a set of the MMC rotors and had a discussion about them. Only made a year or two (I believe you are correct about the supplier). IIRC, we also discussed that they didnt work well when wet, and needed to be "primed" before heavy braking.

Maybe I am FOS. I'm tired and want my car already and cant think logically anymore.
 

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hey guys,

I've honestly never heard of a brake not working while wet. Was it possible that they used the term wet with cold? Some pads as you know need considerable amount of heat to work. Water to rotors/pads would boil off after a couple applications.

Even with economy pads and economy rotors on a economy cars, water doesn't affect the performance much. Since braking creates over 100 degrees fahrenheit after the first few applications coming down from 45.

I know some rotors can get greasy if the wrong pad/disc combo is used and that "could" make them feel wet and feel like they are sliding instead of biting.
 

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rbehny said:
I've honestly never heard of a brake not working while wet. Was it possible that they used the term wet with cold?
Nope.. MMC's in the wet give you about 2 seconds of absolutely *no* decelleration at all before they do start to work again.

The problem seems to be twofold in this case:

- The MMC discs themselves form a slightly porous surface layer that water easily adheres to
- The original MMC pads (special pads, not suitable for iron brake discs and vice-versa) were also quite porous, so they soaked up water as well.

Combine these two and you see that it takes a 'significant' time to get the pad and disc surface to build up some friction in the wet.

MMC's also relied on adhesion-braking (pad and disc create a reaction layer, which 'fuses' them very briefly and this is then broken by the movement of the car) instead of using a largely friction-based setup like most iron discs/pads use (race pads usualy switch to adhesion once they heat up to hich temperatures). This process was also impeded by the water film between the disc and the pads on the MMC's.

Because the Rover powered Elises have non-assisted brakes this effect is also much more noticable. Even on my S2 with iron discs I definitely notice that I need much more pedal pressure when the discs are wet to get the same brake force compared to dry circumstances. Brake boosters make this much harder to feel.

Bye, Arno.
 

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Discussion Starter #9
Bummer.
I misunderstood that Brembo had taken over production for the SE rotors, and assumed they had everything sussed out for S2 production.
I can see where the MMc material would hurt autocrossers.:eek:
That would be a loong 2 seconds.
Cheers all.
m.
 

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Modern Wedgie said:
Arno does know everything! :cool:
Gladly so! He's our proverbial, "Wizard of Oz (Netherlands)"
 

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Naah.. Don't know everything.. Just tend to accumulate lots of useless trivia :)

Oh.. And in the dry the MMC's are pretty much un-beatable when it comes to pedal feel and feedback. I'd say they would be perfect for the auto-X events as they also work directly from 'cold'.

And although there are no new discs available anymore since Lanxide went bust there are still a lot of people running them.

Because the braking does not rely directly on friction braking it means that the MMC disc rotors actually hardly wear at all. It's the pads which are slowly worn down and then replaced. (you could even argue that the discs actually get *thicker* when braking..)

If you look at an MMC disc with 50K miles on it, it looks just like new.

The wet braking issue has now been reduced significantly though since some new developments have been made on brake pads for the MMC discs. These are now made form a different base meterial and are much less porous.

The remaining issues with the MMC brakes (and why you still have to replace the dics before they wear out) are also twofold:

- They can melt on road-race events. The MMC material has a lower melting point than steel and if you have enough horsepower and a twisty circuit then you can overheat them. The surface of the disc melts and they are pretty much toast.

Like this:



Machining MMC discs is very difficult as the material itself is so tough, so these are for the trash.

- They can show metal fatigue around the hub. Several cases where the disc itself has broken away from the center piece. The repeated heating/cooling cycles probably make the MMC material brittle and after several years they sometimes just 'give up'.

So unless a new manufacturer is made for MMC discs they will slowly 'die out' on the Elise. Pity as they were very, very light and worked very well in the dry..

Bye, Arno.
 

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Yup, they are great. I've got them on my S1.

MMC's are much lighter (about 1/4 the weight) than iron brakes.

One of the reasons they are so expensive to make is the patented process lanxide created to cast/machine them. The yeilds were low, under 25% of all castings becoming usable product.

Lanxide are now part of High Performance Materials Group, L.L.C.

Craigy.
 
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