SPDFRK

This page has a few contradicting specs to what I've seen before. It is saying 19" wheels (unlikely) but I hope it is true because there would plenty of room for the 14"f/14.2"r rotors with six piston calipers:D

http://www.fasterfords.com/mazda/rx8.htm

Quick_lude

Hmm.. on one hand I'd love to have those brakes on the car.. but on the other the extra size/weight of the tires will slow the car down.. and the cost for a good performance tire like the Bridgestone S-03 is $250 US each! Or $400 Cnd for us folks in the Great White North.. That is very expensive for me..

Rich

Wierd. I really hate web pages like this that don't include a date. Didn't the R&T article say that they'd offer 16" and 18" wheels? Is this an update since then, or was this prior to the R&T article?

I think 18" wheels are too big, much less 19s! Keep in mind that usually bigger brakes do nothing to reduce stopping distances, and they increase unsprung weight, which hurts handling. Big brakes just help with brake fade, which really only comes into play on the race track. I'd rather have it come with slightly smaller brakes, and those that want to take their car to the track can add something from the aftermarket. One of my biggest pet peeves is that auto manufacturers usually add things that *hurt* performance on their performance packages. Mazda's not immune to this, the Miata's "sport package" adds bigger (and heavier) wheels, and bigger (and heavier) brakes. Argh! At least they didn't include the spoiler...

SPDFRK

for you guys worried about it I doubt they will have anything close to that on a base package may offer track package similar to (dare I say) the 350Z, I will most likely be dumping the stock rims and tires pretty soon along with getting some kind of upgraded brake package if they don't (I love the looks of cross-drilled/slotted rotors plus I have cooked stock systems playing on the streets before). If you caught it they also say their will be a auto/manual 6 speed trans so they may be dating themselves because we are pretty sure that won't be offered. I'm kind of skeptical of the info provided but the Mazda official site says there are 17" ventilated discs but we all know that is a typo unless they have developed a first in the industry perimeter braking system to go on a sub $30k car (hopefully) and are not unveiling the technology

Sputnik

You should be able to fit 14" discs under 18" rims. I'd want the smallest wheel that can fit a decent brake package, personally. That's what I normally end up doing when upgrading my other cars.

---jps

SPDFRK

It would be real tight but I think it could be done. I would prefer 18" rims also because tire selectoin is much greater, cheaper prices and better ride compared to 19's. I have 18" rims on my 328i right now and love them.

applejax

Please explain.

Brakes convert momentum to heat. When a brake gets too hot, performance decreases. Larger brakes = more surface area = better heat dispersion.

No?

Hercules

That's right. And that's why having a cross drilled rotor allowed for better cooling/ventilation, and allows the brake to bite better.

fuz

You guys should really read this:

http://www.bimmerfest.com/forums/sho...ghlight=brembo

Cross drilled rotors, while great on the track, are mostly useless on the road, and are there mostly for looks. Slotted rotors are a much better solution for performance braking, but sloted vs cross drilled vs stock is a much more complicated affair that involves much more than just the disk.

When you have maxed out your resources, it's all about making trade-offs to best suit your application.

In any case, one thing is for certain. Cross drilled rotors crack after very little useage. (Usually well before 20k mi, or even just a day of at the track) Highly impractical, unless you can afford the cost of constanly replacing your rotors.

wakeech

depends on application. again, yes Rich is very correct in syaing that bigger brakes do absolutely nothing to shorten stopping distances for a road vehcle, unless you're doing 300 km/h on the highway or somehting (like +190 mph).
the determining factor in stopping distances is how much grip one's tyres have on the road. if your brakes can lock you wheels at a given speed, your brakes can generate more friction than your tyres, thus making your tyres the limiting factor. but yes, if at a given speed you CANNOT lock your brakes (again, for road tyres, that'd be at a fairly stupid speed for public roads) then larger rotors/more aggressive pads are necessary.

the ONLY thing that bigger brakes do is reduce fade. i've never encountered brake fade EVER in ALL of the road cars i've driven, and i like to brake aggressively (because where i live there's lots of road, and not too many people on it). even the POS 8" rotors on the Echo could (i'm pretty sure, obviously not stupid enough to try it) lock the wheels at 100 km/h, which is the highest legal speed limit on the highway around here (just +60mph). so, bigger brakes would do absolutely nothing for stopping performance until i got wider and softer rubber.

about the cross-drilled thing: yes, they crack VERY easily. not that i've ever had them, but EVERYBODY who i talk to that does tells me they've "just cracked one last month" or something like that (always hotrodding idiots... ). but yes, on the track, why would you bother with anything else?? because of the large decelerations repeated many MANY times PER MINUTE, brake fade is a big concern. i don't know how any sane person could challenge thier car in the same way, considering that there'd be traffic in their way, or that they'd probably crash it (not i'm suggesting it would be by their own fault only: there's stuff on roads which can shred tyres nicely at high enough speed).

truly, slotted/drilled big rotors and brake assemblies are only for racing, or looks. for a road car, they're just a waste of money. oh, and btw, in the highest levels of racing, teams will ALWAYS opt for the SMALLEST brake option that would perform adequately... F1 teams often use brakes which are smaller by diameter and width to reduce unsprung wieght (enhances ability of suspension to adjust to contours of the road).

Quick_lude

I would like to see steel braided brake lines on the car, brake fluid with a very high boiling point and 4 or 6 piston calipers.

Rich

Wakeech said it better than I could have. Here's a link for a Car and Driver article on brakes, that happens to have been written very recently. Here's a quote:

"Assuming a brake system is properly balanced, strong enough to lock a wheel, and not yet hot enough to fade, the stopping distance is largely a function of tire traction, not brakes. Think of it this way: All brake systems, stock and aftermarket, are able to activate the ABS, so how could a stronger brake shorten a stop? Eric Dahl, a brake engineer from Brembo, put it this way: "Don't expect the brake kits to stop you sooner, but expect the 20th lap to feel like the first.""

They did find that the aftermarket setups were slightly (9-20 feet) better than the stock kit in a single 90 mph-0 test, but that's not too significant in my book. I'd be curious to know if that was due to fade setting in already, or if they just weren't able to grab quite as hard. It could also be experimental error, since we don't have the raw data.

SPDFRK

Fade (gas buildup) will definetly come into play from 90mph most magazines still test from 60, C&D now does there tests from 70mph and that starts to show the true performance of a braking system. The shortest 60-0 stop I remember seeing from a stock car is the new G35 @ 110ft if you go by that stat alone it will out stop any porsche or ferrari for that matter. If you take that car onto a track or even the highway and do a few repeated hard stops you will see braking distances almost double that is where a quality brake system will show its worth.

babylou

Sure many factory brakes will fade at the end of a 70 mph or 90 mph maximum braking stop. However, when was the last time you ever had to go from 90 to 0 at full force? Maybe 90 to 50 or something. By then you have either crashed or avoided impending doom. For this almost all factory brakes are adequate.

I prefer reasonable sized brakes that are lighter so handling and ride are better. To boot the reduced mass will also improve acceleration, reduce emissions and fuel consumption, increase crash safety and maybe cost a tad less.

wakeech

thank you, baby lou... exactly the point.

oh, Quicklude, very nice idea. performance items like that (the braided brake lines, and higher DOT fluid) are always a benefit: solid brake feel (and leak resistance too, right??) and combustion resistance are always pluses, i suppose even for daily drivers who live in california, near those deserts (and i say that 'cause this seems like SUCH a californians car... designed by the Irvine team, right??)... :D i'm not trying to seem ignorant!! if the desert isn't THAT hot, please don't get mad!! :D i'm only a lowly Canadian, who's ventured as far from home (and as far south) as central Oregon...

but calipers with so many pistons?? maybe if the master cylinder was really small or something... that just seems kinda big for your average sports-sedan... what're the specs on the BMW 3?? they've always been the leader (at least as long as i can remember) in this category...
i'm sure they'd have phat bite, but would maybe make comfortable driving difficult for your low-to-average-skilled pilot...
(i mean for the jerky stops...)

fuz

All we need is just enough braking power to max out the traction on all street legal tires, and high fade resistance--that's it. If someone is serious about taking their car to the track, they will make modifications on their own. There is no point in all of us paying for that expensive braking system if it only shines on the track for the few who take it there. I drive my car hard, but I'm not insane enough to drive on real world roads like it was my own personal track. Things like oncoming traffic around blind corners, and pedestrians make it JUST A LITTLE RECKLESS.

I only need a braking system that can keep up with "highly spririted" driving, not an all out 10 lap track run. I like to look back on the miata philosophy. Maximum efficiency with minimum excess. We should only get what we need--no more no less.

Remeber, we also have to use the brakes for real world driving as well, so they have to be tuned for making stops at less than optimal brake pad temperature. I highly doubt someone will drive an RX-8 in the snow... but you never know. I did see the pic of ABS testing in Sweden in the snow.

BlueAdept

Woah! Man... Dont even go there.....

One time in my Senator, (no picture but it was lowered and had uprated suspention etc... ) after spending an afternoon servicing it and cleaning it, I went out for a quick blast round the lanes near my house...

You understand that these are windy hedged tracks with MABE enough room for oncoming traffic to pass in SOME places. You have to rely on seeing oncoming headlights reflecting off the hedges because you can't see round the corners more than 50 yards. And with a speed limit of 60Mph (100Kph) it can be really fun.

Anyway, enough reminicing... I got to the point where the brake fade (Mintex performance pads) was so bad that the maximum pressure I could apply would stop the car in about 80 yards. I had to stop and peer at the gently glowing disks for about 30 minutes before continuing.

Give me the knee shooting bigguns, and plenty of cooling airflow.

Grimace

My 8 will be a year-round driver, which means at least 4 months of snow where I live.

You haven't lived until you do a few doughnuts and power slides in the slippery stuff (in an empty parking lot of course!)

I used to drive an RX-7 year-round too.

Sputnik

Heck yeah! During ice storms in Dallas (but I grew up in the snow-belt), I go drive around at night, when noone else is around. It is a thrill driving your car on the "limits" at 10 mph. And I'll tell ya, a balanced car on the ice has as much of an advantage as on the dry stuff.

---jps

Hercules

The rain is more fun :D

Besides, I burn the crap out of my tires and do it on dry asphault... stupid yes, but hell of a lot of fun.

I did a reverse 180 in my friend's M3 (he drives it like a baby), and he freaked... was so fun :D

I wanna do it in MY car now!

stan11003

I hate to sound like a old fart (I'm 23), I once crashed my BMW 528i into Large 18 Wheeler during a rain storm. The cause of the accident was a bad rear tire which was bald as baby's butt on the inner portion of the tread where I could not see. This came from doing some childish donuts two nights in a row. The stock Continentals just melted. They drove fine on all those dry days bit once we had the first rain my backend went infront of me going 60 MPH!!! Luckily BMW build there German sedans like tanks and I was not hurt but it took $7K to fix it. So be careful

SPDFRK

Rain is the closest thing I can get here in AZ but it can't come close to playing in the snow back in MI. I used to get up early to beat the plow trucks to my schools parking lot and that is saying a lot.

Quick_lude

Like others mentioned, the tires are ultimately the deciding factor for shortening one time emergency stops.. Assuming the RX-8 comes with hi performance summer only rubber and not "all-season" tires, those stops should be nice and short.
The reason I would like the extra goodies is, I do plan taking the car to the track and don't want to pay extra money for the upragdes. :p Selfish yes.. :D

MikeW

Usually the largest brake rotor you can fit is the wheel diameter minus 4"

I would assume that the RX will come with big enough brake. But brake cooling, are there brake cooling ducts upfront?

Forget bigger rotors, go smaller tires. If the stock 18's are 225/45 then if you use 235/40 tires the brakes will now be more powerful, if the tire does not slide (more friction) then the stopping distances will be cut.

wakeech

unless fundamentals in automotive design have changed without my knowing, i'd say that the RX will have some sort of (probably deminutive) brake cooling system,with those ducts on the front of the car hooked up to the front rotors... i guess...