ARD T2

iTrader: (22)

I confirmed that the Endless 6 Pot Mini brakes from a client of ours also sit under the factory 16" wheels. It's nearly a 13" rotor as well.

Rishie

Eggie

Could someone send an RS/RZ front caliper to RB? Would be good to check what its max rotor size is.

ptrhahn

iTrader: (9)

Even BETTER would be a 2-piece, 13" diameter/stock width rear rotor w/ a relocation bracket for the OE 93/95 rear caliper. Who needs to buy hundreds of dollars worth of new 99 calipers, when they're the same thing with longer ears?

You could go right out to 13" to match virtually every aftermarket front BBK out there, instead of the 12.5 or whatever the '99's are.

GooRoo

iTrader: (4)

Doesn't surprise me much, as I was looking at my calipers last night trying to figure out how you'd get that large of rotor in there without filing off a bunch of material.

Anyone know how the Mandeville setup gets around this?

I'm all for new calipers as long as we can keep the cost down and increase the performance a little by doing so while keeping it all balanced. Oh, it'd be nice to have good pad availability too.

RaceDriver7

iTrader: (9)

I think RB is on the right track with the direction they are taking. Some people seem to be giving them a hard time. I'm personally truly shocked that the founder of the company has taken the time to read our posts and respond in our forum. He can't be expected to satisfy everyone's need and the costs and production volumes need to be taken into account. They are a business afterall and need to be able to make money off of this. FD's are already a low volume production in the US so it's really great to see a company putting in so much effort to satisfy our needs.

Adding 99' spec rotors to their line might be beneficial as well as there is a pretty high demand for those. They could also sell these internationally where the 99' spec cars exist. I agree they should consider it.

I have the 17" Ekei RPF1's and the spokes come very close to the stock calipers already. There is probably a few mm of clearance. It would be nice if the rotors were engineered to clear these wheels like they did for the RX-8. If you need me to take any measurements I'd be happy to do so. The wheel dimensions may already be available online too. Typical sizes are 17x9 +45 front and the same or 17x9.5 +38 rear.

- Michael

GooRoo

iTrader: (4)

One more thing... what piston sizes are we looking at for the RB caliper? From my calculations it doesn't appear that we need much difference from stock.

Thanks.

Howard Coleman

iTrader: (6)

i know what the front bore size is and while i can't currently disclose, it will be perfect as to uprating the overall performance of the system. it is sized specifically for the fd.

stay tuned please.

howard coleman

GooRoo

iTrader: (4)

Ok, np... then I'm going to try to guess to see if I know what I'm talking about...

<<JUST A GUESS PEOPLE -- Unofficial!!!>>
I'd say for a agressive street/medium track setup according to my calculations if we're going to use a pad with a Mu of about .5 at temp (something like Hawk HP+ or even HT-10's?) and we're going for a goal of about 1g's at max we'd want a 34 leading and 34 or 36 trailing. That would put us at about 82 lbs of pedal pressure, which would be about the most you'd want to do repeatedly. 69.7% front brake torque and 67.4% front weight at that decel rate, so that should work for the best street tires out there with a small margin to make sure the fronts lock first.

If the pads are bumped up (not sure what the Mu of the DTC-60's is) to more track only pads at Mu = .6ish then I'd say we could run 36 lead and 42 trail (or 38/40)... That would run out of front brake at a decel rate of 1.25-1.3ish g's... And if I you use the 929 master cylinder (1") to firm up the pedal it would be 77 pounds of pedal pressure. 73.2% front brake torque, 72.2% front weight at the limit. That sounds like something I'd buy. (I'm running 255/40/17 RA-1s)
<</JUST A GUESS PEOPLE -- Unofficial!!!>>

Am I right?

Howard Coleman

iTrader: (6)

you are as close to being right as the Stadium View bar is to Lambeau Field.

as an aside... i note you are using differing leading and trailing bore sizes. do my soon to be replaced AP5200s have different bore sizes? uh, no.

will the RB calipers have differing bore sizes? uh, yes. it is the way to do it right.

howard

jimlab

They should, mine do.

Howard Coleman

iTrader: (6)

i will recheck.

hc

Howard Coleman

iTrader: (6)

1.5 and 1.625 bore sizes... on the AP5200s.

hc

GooRoo

iTrader: (4)

Excellent, that's what I like to hear. Haven't been to GB in a while, but I assume the places haven't moved.

I've certainly noticed that my pads wear more on the leading side than the trailing at high pressures/decel rates so I'll be happy to have something setup asymmetric so I can make more efficient use of my pads.

GooRoo

iTrader: (4)

Are your rotors 328's or 332's? What is the pad width? Just curious.

SkulkR1

iTrader: (1)

I was also interested in how Mandeville used stock calipers with larger rotors, as was questioned earlier by GooRoo. Comments?

jimlab

There's lots of information about Mandeville's kit on Rob Robinette's old site.

http://www.robrobinette.com/bigbrake.htm

GooRoo

iTrader: (4)

Thanks... there's a bunch of interesting information there. I didn't read, and don't see in the pictures, exactly how they got that bigger rotor in there...

I'm guessing it's just missing the outer edge of the pad a little so they can get the space they need.

GooRoo

iTrader: (4)

For anyone who is interested, here's the Excel spreadsheet I've been playing around with.

I have several different setups on there for comparison purposes. For the most part I adjust the pad coefficient and the desired decel g's and then I modify the input pressure to get the decel g's on each setup to match the desired decel g's. Then I compare the weight transfer numbers with the percent torque numbers, the goal being to have the front% just a bit more than the weight transfer to make sure they lock first.

If you want to find values for your car, you would have to modify the car weight (I was using 2826 for stock values) and potentially the piston area (there's a calculator for this at the bottom) and tire radius (I was using stock 225/50/16 size) values as well.

General CYA: I make no claim as to the validity of these numbers.

However if there is anything wrong let me know so I can fix it.

BrakeSystem.xls

Eggie

Nice one! I'll have to use that some day.

First look at the sheet prompts a question: exactly how big is your monitor?

Calculations mostly look good, but I only ran through the stock brakes. Figure everything else is cut & paste, so... Just a few items of note.

Column I is wrong. Need to reverse the radius and 12. This doesn't affect the bias, of course, since you used the same tire size F&R. Will definitely affect the pedal pressures required to get to your target.

I'm pretty sure the RZ rear rotors should be 12.36", not 12.2".

I'm still not too sure about how to model the vacuum booster, so I just tweaked my spreadsheet to match yours there. Time to dig out some books, I guess.

GooRoo

iTrader: (4)

I was running a multimonitor setup, but I had an opportunity to trade it for a Dell 24" widescreen lcd, so yeah, it's pretty high res.

Yep, 'I' was backwards. I switched it and updated the pressures.

The RZ rotors measurement I found people saying both, so I went out and measured one of Damian's old rotors and it was 12.3 (313mm) however the pad was not hitting the edge, so there was a pretty good lip there, so I went with the 12.2.

I just went out to check again and still got 313mm/12 5/16 inches. I do know the rotors I'm checking are OEM Mazda ones.

gracer7-rx7

iTrader: (16)

(Mandeville) They essentially split the caliper lengthwise and add a spacer between the caliper halves. I saw a picture of it on this forum somewhere...

jimlab

I believe he meant bigger in diameter, not width. The link I posted above shows pictures of the spacers used to increase width.

GooRoo

iTrader: (4)

Correct, I should have specified.

Herblenny

iTrader: (13)

Any updates on this?

Howard Coleman

iTrader: (6)

after 174 posts, lots of give and take feedback and work on RacingBrake's part here's where we currently are:

as per RB on Feb 10 the FD will have a brand new much higher performance set of four purpose-designed rotors that are bolt ons. the front is a touch thicker and the diameters will be of stock dimension.

sounds ho hum? not really.

made from a proprietary alloyed material
centermount hub to rotor design equalizes heat transfer between inboard and outboard frictional surfaces
forged aluminum light attractive hats
centermount rotor acts as the intake for air flow thru the rotor
LARGER airspace than OEM adds airflow
convergent vane design promotes airflow and strength
superior brakepad will be available
front will have slightly more ring mass
curved exterior slots
good lookin'

these will be the best bolt on rotors ever run on the FD.

April 15th will add the second RB brake option specifically designed for the FD.
designed to significantly upgrade brake force while maintaining correct longitudinal bias.

the front rotor will be 328mm or 12.91. thickness will be 28 mm or 1.1 inches.
the rear rotor will be 322mm or 12.67 and will be 20 mm thick (.79) so as to utilize the OEM rear brake. in order to use the large (diameter-wise) rear rotor RB will specially make a caliper relocation bracket.

RB will purpose-build a 4 piston front caliper complete w a mounting bracket and staggered piston sizing to promote even pad wear. the caliper will be specifically sized to match the rear caliper bias.

brake pads will be a major part of the performance upgrade. warren has put lots of work into the pad options.

brake torque will be way up w this setup.

there has been talk of making another caliper mounting bracket to accomodate the 99+ rear caliper to the RB bigger rotor.

there will be other options, perhaps, out there a bit timewise but the above is what will be offered by RB in the near term.

thanks warren,

howard coleman