D Walker

iTrader: (1)

I can look today to make sure I am right, but the RX7 and Rx8 calipers are totally different. The RX7 uses a smaller disc (came with 16" wheels IIRC) and a 4-piston caliper, the RX8 was designed from the word go for 18" wheels and uses a larger disc and a sliding caliper. At first glance without taking measurements it does look like the RX8 setup would bolt onto the RX7 wiht minimum modifications.
We use a Mazdaspeed supplied duct-made by Speedsource but easily fabbed if you have the tools/talent- and the aforementioned Cobalt pads. Over this season we ran 5 Pro races, several Club races, and many trackdays on a single set of rotors. In fact, those rotors are still on the car and are good to go for at least testing purposes. We used changed front pads once this season I believe, would have to check the records. I do know that when we changed the pads they were still OK for use for say, a test day or club weekend, just not what we wanted for a WC weekend.
If I were allowed -and we are not in WC- to upgrade the brakes I would use the Performance Friction calipers/rotors or the AP setup. The AP setup is serious money, the PFC is less money.
If you guys are blowing through brake pads- especially good pads like the PFC 01's etc.- then there is an issue somewhere. I would start with ducting and work my way back from there.
The reason you did not find an FD application for the Cobalts is that they virtually custom make each set of pads on order. As far as I can tell, they only stock pads for popular applications, and even if you think it is a popular application they may not have it on the shelf. This is the only frustration I have with them, as I have to order pads weeks in advance of needing them. You might need to send them a sample for a stock FD caliperand expect to wait about 2 weeks or so for them to run them through. They are racers and they are at the track as much as anyone so they know whats up and are great to deal with.

D Walker

iTrader: (1)

The problem with the FD is it was designed for a 16in wheel and has a small diameter disc, and this is a serious issue for good braking. The RX8 was designed with a larger diameter rotor from the word go and the greater torque arm effect is the largest difference in braking. The ABS is better too, and FWIW I believe, having looked at both cars with an eye towards this, the RX8 Hitachi ABS (non-CANbus) would be a very easy drop-in for the RX7.

You would want to put the catalog away and call or start an email dialog with one of thier engineers. They do have a vast assortment of calipers, rotors, and pads etc. and if you give them the car weight, tracks or types of events your going to run, and your expectations they will be able to help you with at least a good starting point. The engineer there I am currently working with for the Grand AM cars is a pretty sharp guy, and I can see if its OK to post up his contact info.
EDIT- as a price point comparison, to replace the (race not street) Brembo setup on the Challengers with the PFC brakes- calipers, rotors, pads, etc fnt and rear- is abotu 6K a car. This may be a price given to Grand-Am competitors, but still should not be far off. With some street car BBK's nearly 6K for the front alone, I would see this as a good value.

Not getting into specific details there are issues with the Stoptechs when used as anything other than a streetcar fashion brake upgrade. I really do not like thier caliper design. Meyers I know tried two different setups and still was not able to gain any advantage over the stock caliper other than the two-piece rotor acted as a heat barrier and kept some of the heat out of the hubs, which he felt allowed his ABS sensors to live longer. I never had any such issues myself. The thing I would stress is that no matter what is says on the box, these are kits designed for streetcars as a fashion statement first and for a performance advantage second. In all seriousness you would be better off to get a set of Wilwood calipers at half the price
Dino is smart however and a great businessman, Centric (who owns Stoptech) also owns a lot of other brake companies, and there is now some tie-in with Cobalt. It would really not surprise me at all if he made a push for further development.
I will be glad to go into specific details of why not to use them over a phone call or in person, but that is about the limit of what I feel comfortable putting in writing, PM or no.

Fritz Flynn

iTrader: (263)

I've heard issues with cooking seals and I think Pete had that problem as well but as always you get what you pay for and for 1500 the ST kit is a much better kit than some of the other budget kits out there.

Not surprised you are out braking your competitors on stock brakes which are probably lighter and perfectly matched to the ABS setup but I'm guessing you are also blowing through pads and rotors. Doesn't matter at the pro level but us no budget amateurs do everything possible to save are equipment from damage. If you guys don't have ABS then I'm VERY VERY surprised you are out braking your competitors especially with Cobalts (not a fan) so it can only be the driver has a good shoe or Mazda built a hella good stock brake kit for the RX8

PFC is pricey on all their equipment but IMO it's the best brake stuff out there dollar for dollar but like Pete said I don't have a clue about which caliper to use and Stoptech would know what the FD needs. The current Stoptech kit I have bolted on my car has better bias than my GT kit but that's the only place there's an improvement. I'm sure I could call Brembo and explain that there's is just a little bit of front bias and they'd come up with a good solution but I also feel it would be expensive because Brembo products have a well deserved reputation surcharge.

Dave McLaughlin

Pete,
I did like that about the RB kit (keep the e-brake). I don't think I'd want to be without it either. Since I already had an RZ rear end here at the shop; I decided to go with the 99 spec rotors from Mazda Motorsports and just swap out the caliper brackets along with the larger rotors. It just seems to me that Stoptech could at least do what Racing Brake did and give us 2-piece rear rotors and brackets for the OE rear calipers. I will be installing the 929 MC I got from Ray Crowe along with my total upgrade. I want the same "super firm" brake pedal you describe and that Fritz was going-on about @ VIR a couple of weeks ago.

Fritz Flynn

iTrader: (263)

Pete's car is a freak it's the only FD I've been in with such a hard peddle. It's basically abi normal in a good way If I tap up my peddle which I have to do anyway because the front pads wear quickly my peddle feels great.

No need to fix something that isn't broken. Our rear brakes are fine for the power levels we have. My rears last twice as long as my fronts and work well.

Two piece rotors are a PIA with much greater chance of warping etc.... so as long as we can get the 99 parts I see no need to change.

Take the money we save on rear brake rotors and pads and lighten the car somewhere else or add safety etc.....

PS if you really want some two piece rear rotors Precision Brake can help you there but again IMO it's a waste of money.

D Walker

iTrader: (1)

No we do not blow through equipment see here:

I should also mention they are the set of rotors that came on the car when I picked it up from Tom and he dcould not remember how many races they had been on the car, and yeap, they are still on there and still in awesome condition.

It is probably also helpful to poitn out this is a 2650lb (empty) car that starts the race at just over 2900 (fuel and drover) and finishes at 2800-i
sh

Fritz Flynn

iTrader: (263)

The weight is a big difference but more importantly is the speeds we'll see versus the RX8. I hit 160 both front and back at VIR. I could buy a 25k ceramic move it kit and still probably wear em out

As you know there's a huge difference in brake wear from 100 mph and up and from 140 to 150 is probably 2 times the wear, 150 to 160 4 times etc.....

ptrhahn

iTrader: (9)

Yup... my car with me in it and a full tank of gas is about 2930 lbs, and we're pulling down twice a lap from 160, using 285/30 Hoosier DOT tires. Still though, that's no more than the GT3's and Z06's out there that are heavier.

I am willing to believe, though, that there's something more to it—including a technique issue. It DOES seem like the rate that I/we going through pads and rotors is high—and on the pad side particularly since I'm not willing to use the last 3/16" or so of pad due to heat transfer to the calipers, even with Ti backing plates. I've got pretty decent dedicated ducts up front, may look at improving them, but still.

Fritz Flynn

iTrader: (263)

http://www.rx8club.com/showthread.php?t=204813

If you guys are running 2.13s or so at VIR it all makes sense.

Bottomline: it's the speeds we'll see in the modded FD that's killing our brakes.

Fritz Flynn

iTrader: (263)

Yep and T1 cars are replacing rotors and pads after a weekend of racing. P cars came with REALLY good brakes that will last fairly well but there's no majic bullet for both tire and brake wear on a high HP car.

Pete the answer is in rotor size and thickness and pad size and thickness. Ducting helps some but if the brakes are too small and thin no amount of air will save em.

My RS has 15 inch brakes with MASSIVE pads both thick and long and I replaced the fronts after about 4 weekends or about the same as the FD with the GT kit bolted on. RS kit has decent cooling ducts and the FD has good cooling ducts.

D Walker

iTrader: (1)

I have not run the car at VIR, but we did 1.36's at Mid-Ohio this year, so maybe use that as your yardstick? That video was from a couple of years ago and was on Toyos, not Pirellis that we currently run. our time at RA on Hoosiers was in the 1:38's running relatively conservatively. Remember that we only have 225whp and run a rules mandated 17x8in rim and Pirelli DH compound slick. Originally we thought the slicks were going to overtax the brakes compared to the Hoosier or Toyo DOT's, but they seem a near perfect match.

Dependant on drover we can see 2930 with a full fuel load, so weight is about the same looks like.

There is also likely a difference in braking technique as well. Chip, JD, Jason, and Dan have all been extremely impressed with the car under braking and once they come to grip with the way they need to drive the car are able to put down extremely fast laps. If you happen to be in the area and the track is open you are welcome to take a few laps in one and see what you think.

Dave McLaughlin

Fritz,
I feel good about my decision to go with the 99 rear rotors. It was by far my cheapest date and I like the fact that they hold up well (according to you and Brent). I was just thinking that ST should offer the rears as an option under the circumstances. I will definitely be lightening my car this winter. Looking forward to some more schooling with "The Master"; as Brent would say. Cheers!

Fritz Flynn

iTrader: (263)

Would love to try an RX8 race car. I've been on the track with a few and they look like loads of fun.

Technique is always a part of brake wear as most of us over brake but both me and Pete get threshold braking and go in with a balanced car at a decent speed of course we could do it better but who can't However I don't think his brake wear has much to do with technique it's basically going 160 mph and slowing to 50 that kills the brakes.

I brake just inside the 5 and if I reduced my speed to 140 I can brake inside the 3. Eric was probably braking at about the 2 at 125 or 130 and my car could do that with virtually no brake wear.

I've never been to RA but Brent who also has a TTS FD runs 33s there and will likely drop that to a 31 this coming year. Basically the typical track prepped FD is going a lot faster with much more tire which is what's tearing up the brakes. I'll get about 4 weekends out of my front pads and around 12 out of the rotors. However these are weekends going 3 or 400 miles.

Fritz Flynn

iTrader: (263)

Yep even the stock rears hold up well with 13 inch front brakes although going beyond the 13s could make the bias a challenge.

Look forward to hanging out some next year

TrentO

I'm running a custom Wilwood setup, built around a 12.9" x 1.25 GT 60 directional rotor. The added rotor mass with the thicker rotor allows the brakes to take the extra heat from the hard stops. I'm running 18-19 lbs of boost, which dyno'd at 459 rwhp. At the Edmonton Indy this year I was able to pull the car down from around 155-160 mph to 30 mph lap after lap without any noticeable fade. Many of the other cars (GTA style stock cars mostly) were having braking issues. I run a direct 3" duct into the rotor and Use the Willwood SL-6 caliper with the 1/2" thick brake pads. I managed two seasons on the pads before I changed them out due to the start of taper wear. In my mind, the stock rotors, regardless of year do not have enough mass to absorb the heat. Once you go above 400 rwhp you really need to step up to a much greater mass for the rotors to have any hope of longevity.

-Trent

racingdriver

I have run my 93 rx7 since 1997 and have tried many combinations. Our track is super hard on brakes , ie. 220 kmh into a 1st gear corner! Here are some of my experiences.

The stock front brakes are too small for anything over 350 hp. My first upgrade was the brembo F40 kit (38/44mm) with 13 inch stillen rotors. These rotors were way overpriced and didn't even last very long. The pedal was low and needed a 929 mc. With the 929 mc I was still unhappy with the pedal feel and changed the pedal ratio by modifying the stock pedal to a 2.85 to 1. This gave a pretty firm pedal. The next step was i used the 94 supra turbo fr. rotor. It was cheap and 12.7 x1.2ish. I had to enlarge the center hole and had a machine shop make new mounts for the calipers. This was a great set up with the stock rears. I was still losing out to the Porsches and without good ducts the brakes were very hot.

I should have built good ducts.

Instead i found out the srt8 Chrysler has the same bolt pattern, center hole, and a good offset for the rx7. I had another set of mounts made for the calipers and ran these srt8 14x1.25 rotors with good results. And they are cheap! But....... Now the car would understeer in trail braking. Too much front bias. So I used all the left over supra front rotors and put them on the rear, cut them down to 1.1 , and used a c5 corvette caliper. The stock rr rx7 one is about 30mm, the corvette c5 rr is 45mm! Now i had pretty good balance. But now the pedal was less firm , but acceptable. This set up was great at 460 bhp with slicks. But in 2007 we installed a 700 hp 3 rotor. We were again heating up the brakes.

So i went all out with brembo's pro race stuff. 14x1.4 rotor as used in grand am, alum hats, and the monoblock brembo gtr caliper. I took these parts to a very talented race shop( nasport champions) and they said , You really don't need that much brake, you need 5 inch brake ducts! I really couldn't send the new brakes back so they made the hats, adapters, etc.

I made custom ducts that use every inch of the cente of the rotor and 4.5 inch ducts.

This has been a bulletproof set up until this year when we replaced the wiring harness for a race set up, and the stock abs with the s2000 system (twice the ecu speed, 4 wires to hook up.). It seems there are two limiting valves in the rx7 abs that handle the bias. All of a sudden I had way too much rear brake. Even with adjustable bias valve cranked it was not right. Unfortunately we found this out at a track with a mile long straight. And it seems the pedal was softer without these valves . So for this year I have added another in line bias valve and changed out the booster for a miata booster with 1/2 the boost. Now i have a very firm pedal and should have good balance again.

My advice on front calipers.

Most of the calipers on the market, especially the street ones, have a pad that has about 1/2 the meat of a dedicated race caliper. And I found the prices and availablity of compounds for race calipers to be cheaper. Twice as thick means twice the lifespan, and less heat transfer when new. That is a big savings. The gtr caliper I run uses the same pads as some nascar teams and they sell top line (pfc 01) pads with 90% pad left for about $75 on ebay! Sometimes 2 sets for $75!! Also these calipers are super stiff, and are made of a much better grade of aluminum. I have seen these on racecars for 7 years without a rebuild or a leak. I have seen a lot of leaks with wilwood and outlaw after 1 season.

My advice for a track car's front brakes:

You can get proper brembo/ pfc/ap/ alcon race calipers on ebay from nascar stores for about $1200 used. Get a machine shop to make some adaptors , and run the srt8 rotors ($110) or the supra tt rotor . Cheap pads, cheap rotors, and killer heat and stopping power. Ohh, and don't foget the 4.5 inch ducts!

wb

Brent Dalton

iTrader: (31)

Walter,
Thanks for sharing your brake information/experience/progression. That is alot of valuable data in several different dimensions. The S2000 information is especially useful. I assume you are still using the stock RX7 pedal assembly w/ modified ratio and 929 MC?

I've been keeping an eye out on the higher end stuff that shows up at a greatly reduced price used on various sites and spoken to a few brake companies to get a few reccommendations. I want to stay informed so if/when I up the horsepower and need a brake upgrade, I'm in the loop enough to make an educated decision. My plan is the same as yours if that happens: Buy the calipers and rotor rings I want to run, and build a caliper bracket and rotor hat to adapt and fit the system. I've had a few racing buddies doing essentially the same thing as you have done with great success. One is running an Alcon setup from a NASCAR team with some huge rotors and some ridiculously thick pads that are really cheap.

One thing to caveat that you have eluded to: There are a good bit of calculations/math involved to build and size your brake system... as well as some unknowns, such as the restrictions in the mazda abs system. Or compensate other aspects of the system to balance other components. Luckily, with the dual master cylinder set up it should be easier to tune and balance the brake system by changing master cylinders to ensure I have the correct percentage difference between the front and rear. Once that's dialed in, you can go up and down in MC sizes to make the pedal more firm or less firm(which essentially gives more modulation, but you still have to take into account brake system compliance). From there, the balance bar provides I think 33% of proportioning adjustability(if memory serves me correctly) to fine tune variables such as track and weather conditions, etc...

Fritz Flynn

iTrader: (263)

WB,
Awesome info and thanks for sharing

I also have the F40s and like you wasn't happy with replacement rotors from Brembo so I use Coleman Racing who make decent rotors for around 500 shipped and can still maintain the 2 piece setup which probably saves a pound or so.

I can live with the F40s but I'm still not completely happy with my pad and rotor life and the F40s are just a little bit front biased (13 inch rotor) which will always slow you down. I have a decent brake duct setup probably 3 inch pipes with 4 inch hose going to a tight backing plate but I'll bump the pipe size to 4 inch this winter.

I won't run more than 350 rwhp so I really don't have to sweat the brakes too much but I have a brake fixation

Again thanks for the great info it will come in handy when I swap to a different brake setup next year

Brent Dalton

iTrader: (31)

understandly so

BTW, were you creepin at VIR on Monday? Saw a Red FD in one of Jon Felton's pictures that looked suspciously like you in the red 95 R2.

TwinCharged RX7

iTrader: (14)

Where did you find the SRT8 Rotors that match FD hubs? Did you have to machine them at all?

2009 SRT8


1994 FD

Fritz Flynn

iTrader: (263)

Yep just go w/o them one time and from then on brakes will be your passion, obsession, fixation and constant worry

I wish that was me. I'm probably done for the year but might take the RS out for some fun on the Patriot course and F after T giving if the weather is good.

racingdriver

yes they bolt right on. The .6 mm center hole difference is not a big deal, thats .3top, .3 bottom, , the fit is good, especially when you factor in heat expansion. The larger bolt holes make up for the slightly larger bolt circle and they slip right on. No vibrations or issues. One note is some calipers may need trimming to fit a 14 inch rotor. What i liked about using the supra rotor ( which needs minor machining to fit) for many years is you could turn them down and put them on the back, saving a lot of money.

Brent Dalton

iTrader: (31)

Just realized I misspelled you name Wouter. Sorry about that.

Dave McLaughlin

Happy New Year Folks! Just wanted to post the final upgrade and share with everyone. The final install ended up as follows:

a) Stoptech BBK (Race only version) It is biased for the 99 spec. rears
b) RZ (99 spec) rear brake rotors with RZ rear caliper brackets (rotors from Mazdaspeed-Thanks for the part numbers Brent)
c) 93' 929 Master Cylinder (re-manufactured; Ray Crowe hooked me up here)
d) Hawk DTC-70's - Front, Hawk DTC-60's - Rear
e)Pressure flushed the entire system with Motul 600 brake fluid

I am happy to report that the pedal is as "Stiff as a wedding Pecker"...I hope it has as much "Wow" as I think it will. I bet this pedal feels a lot like Petes'; "a freak of nature" as Fritz has said. Thanks to everyone for some outstanding tech input and experience based advise.

Dave McLaughlin

http://www.facebook.com/photo.php?fb...&type=1&ref=nf