brakes

[mranlet]

Those are the kinda of cooling ducts I'm talking about - cheap to make and all benefit! It's not just the BMW guys who do it either. Anyone serious about braking peformance will benefit from the installation of cooling ducts.

I had ducts on my Subaru that were made from a 4 1/2" foil dryer vent hose (although a large shop vac hose may work better as long as the last few inches are wraped in foil tape or a piece of aluminum tubing to resist melting from braking heat) connected to a hole that I drilled in the OEM backing plate. I cut a 4" hole with a hole saw and then used a jig saw to cut a bunch of concentric cuts to the 4.5" line that I drew. Next I folded those tabs out away from the rotor and slipped the hose over them. A good wraping of foil tape and a number of 1/8" holes and washer-fitted pop rivets later I was good to go. Never had any problems and the thole deal cost about $20 (one hose can stretch for all 4 wheels depending on where the vents are).

-MR

[GRiDRaceTech]

MR- EBC makes the Greenstuff pads.

Menchi- Notice that on most professional race cars, they only use drilling or slotting. Combinations are few and far between. You are right on the money about drilled-and-slotted rotors being redundant... one loses too much surface area. If a drilled or slotted rotor is designed right, it'll cool just as effectively as a drilled-and-slotted rotor, but with more surface area. There's only so much gas/heat to dissipate.
Drilled rotors tend to crack if the holes aren't chamfered. Also, a lot of the high-end teams that do use drilled rotors have them cryogenically frozen to help prevent cracking as well.

On braking balance: now we're treading on advanced ground here. If you're going to seriously mess with brake balance to get the most from the car, expect to spend a lot on new tires. Remember that you can't just set the balance from a couple half-pressure stops from 60; you also have to take into account the stability of the car slowing at full pressure at speeds upwards of 120. I would recommend a higher-speed testing regimen for a street driven car so it'd be more manageable under emergency conditions. For the track, well... every track is different. You'd probably have to mess around to find the best setting. If you must set bias on the street, find a very desolate area with nothing to run into and be prepared to make the trip home with flat-spotted tires.

Nemesis- I agree that slotted rotors seem to offer the most advantage, on the racetrack and off. They are the least likely to crack and, with directional vanes, cool exceptionally well.

A novel idea I've seen implemented in the BMW club racing circles is a cooling duct which terminates in a cooling plate attached to the hub. The plate forces air through the rotor's internal vanes and out of the rotor. Thus, the rotor is always cooled and the brakes then run cooler. Here's the link: http://www.bimmerworld.com/e30_installation.htm

[Nemesis]

slotted owns...end of discussion...

[Menchi]

IMO drilled-and-slotted rotors are redundant and a bit worthless, cross drilled did the job well enough but the rotors were usually weakend by the cross drilling process, so to solve this I think it was mazda, that developed (or was first to use stock) the slotted rotor which did were stronger than cross drilled and cooled just as well or better, nwo we have aftermarket companies, going hey lets do both and everyone will think they are better,

another thing is if you *Censored**Censored**Censored**Censored* up the porportioning the rear tires will lose there stopping effect and increase you stopping distance like they mentioned before, HX-50 and I were argueing about this one night and he said some things that made sense, first was, that stopping distances aren't always the most important things, sometimes brake fade, is more important, and sometime, drivers will keep an unbalenced break set up to suit thier driving style, it might help in oversteering around some turns in a rally, anyway, good luck with you search, yes stop tech and project mu are the *Censored**Censored**Censored**Censored*, I prefer fixed calipers instead of floating, and stop tech makes some good ones,

[mranlet]

+1 to Grid

If you can push down on the pedal and lock up the front tires, then you need tires before brakes. Lightweight wheels (Motegi now makes some 10-lb'ers!) and grippy tires will improve your stopping distance and all-around handling right away.

As with anything in tuning, the added performance will demand that you make some sacrafices to reliability and durability. A 400-hp rotary-powered FC is going to be a bear to drive on the street, especially with gas prices the way they are. If this is really what you want to do, then it's probably safe to assume that you are putting track performance higher on the priorities list than streetability. Nonetheless, you'll still want a good set of street pads.

In the hierarchy of what to upgrade first pads and fluid are at the top of the list, with braided lines and cooling ducts (IMO) coming in soon after that. A higher pressure master cylinder will also help, if there is one to be found for the FC (maybe try a 929?). With all of these things in place and a trained right (or sometimes left) foot, even the stock calipers and rotors will serve you well - in my Legacy Turbo I had braided lines, cooling ducts, "Greenstuff" pads (don't remember the company, maybe Mu?) and an aftermarket fluid (also don't remember) sent to the ground through some steelies and Pirelli P-Zero's. Even with the stock 4-wheel discs and OEM calipers I was outstopping Porsches and even some Motorcycles!

For a model of an awesome brake setup (and high-collar ones), check out the brake system on the HKS Time Attack EVO:

Those are 11" in the rear I believe with 4-piston calipers and Endless(?) pads. Up front the setup is the same with 6 pistons instead of 4. Super Street has some awesome pictures of the HKS EVO this month, and the fast facts would say all of the setup stuff.

The Xanavi Silvia:

...also runs 11" up front with slots only with 6-piston AP racing calipers. I remember reading somehting in Racecar Engineering that the holes in the hat are pins that the single-lug wheels lock in to, but that the pins are hollow, allowing the hot gases to be pushed out by incoming air forced inward by the fins within the torot - probably not somehting you'll be able to do on a street car.

Hope this helps! (pictures are cool!)

-MR

[GRiDRaceTech]

Racing pads need a warm-up, decent street/track pads shouldn't.

[--DriftKing--]

well i plan on running around 400 RWHP in my FC using a T04E......and some other things....

but i totally understand waht u mean it would be useless to do it unless u need taht kinda stoping power also dont they begin to work after you warm them up?

[GRiDRaceTech]

Brakes are a yet another passion of mine. Usually stock brakes are up to the task as long as you upgrade fluid, pads and lines. (Up to a point... if you're running 50hp+ more than stock sounds about right) My e30 has Ate Superblue fluid, (higher boiling point than normal DOT3 fluid, both dry and wet) Axxis Ultimate Pads (higher coefficient of friction, better temp range) and Ate Powerslots up front and I haven't had any fade problems, and the brakes are easily modulated.

But... on topic again, drilled/slotted/drilled-and-slotted rotors won't do anything for initial stopping distances. (And may even increase them, like MR says.) It's all in the fade resistance, so the repeated stopping distances will decrease. Even so, without a better set of pads, you might as well just burn money. Brakes should be replaced with upgraded pads, and with proper ducting, blank discs should be more than adequate, especially if you're not going to be doing any HPDEs or extended-length drifting. (Even then, with a good set of pads, it'll be good.) Replace the fluid with Ate Superblue (or the Ate gold fluid) or Motul RBF600 and you're golden. Unless you're packing the heat or visting tracks on a regular basis, an upgrade to gigantic brakes is worthless except for the bling value.

Also, grippier tires will lead to shorter stopping distances, so if you upgrade the brakes without upgrading the tires, there's no point. (Unless you're running really grippy tires already)

[Tuner]

Are you pushing more than stock power? If not, no need for brakes, they're overrated anyway

[--DriftKing--]

i want the best......i have an FC and want a big brake kit and cross drilled rotors...on my rotary....lol....

[nissanguy_24]

Slots and drills also effect cooling by giving the rotor more surface area (dispite lowering the surface area touching the pads) which potentially can cool the rotor faster. which in theory could cool the pads quicker. However the question becomes do the benefits outway the cost? afterall if theres less surface area touching the pad then the rotor cant absorb as much heat from the pad even if it can dispense it alittle better.

So theres the reasoning behind it anyways. For cooling slots and drills it almost seems better to just have them on the area not touched by the pad.. giving you maximum surface area for the pad and cooling. But thats just me thinking about it, im not an expert on brakes or themal systems.

[Tuner]

Try experimenting with pads first before you spend $2000 for a caliper/rotor setup

[--DriftKing--]

oaky oaky i have many mixed feelings about stoptech and brembo...i was underimpression that brembos were the SH!t.....but stoptech makes some really costlly stuff....wahts up with that then i know endless are wahts up.....they are awwsome as welll...well OH and Project Mu arent they good too? and willwood?

can anyone explain to me the ups and downs of these different systems?

[mranlet]

Originally posted by AlexPfeiffer
the most impotant thing in cooling is to have directionaly veined rotors as they act like a fan and suck air through the rotors.

Expelling hot gasses out at the center and sucking fresh air in from the edges.

Originally posted by AlexPfeiffer Older pad compounds would create small air pockets because the material used would give off gases as the hit high temps. So slots where developed to help gases and material to escape from the pad surface.

Is this still a problem? I was under the impression that newer compounds are capable of achieving little to no gaseos release. Are you talking about asbestos-era brake pads?

As for a 4/2 piston setup, you could run the same size rotor on both front and rear (11" would be suitable for a ~2200lb/1000kg car) since braking force will be staggered front to rear. If rotor longevity is less of a concern than ultimate braking force, slotted/drilled rotors ought to be used. Some 4.5" foil dryer vent hose going from an inlet at the front of the car to a bracket on the spindle should provide a good flow of cold air (but make sure to use metal fasteners rather than zip-ties or something which could melt). With more pistons to push, upgrading to braided steel lines and a more serious master cylinder with a proportioning valve wouldn't be a bad idea by any means, but isn't mandatory. Top it all off with the street performance pad of your choice and you'll have yourself a sweet brake setup!

[AlexPfeiffer]

the most impotant thing in cooling is to have directionaly veined rotors as they act like a fan and suck air threw the rotors.

Older pad compounds would create small air pockets because the material used would give off gases as the hit high temps. So slots where developed to help gases and material to escape from the pad surface.

Drilled rotors are done to cool the pad surface at the same time as the rotors and are just a fashion statement without the directional veins and good ducting.