Yes, the M2/ Wilwood 13" brake kit actually fits under stock 16" FD wheels!
 

After I burned up my stock 1993 RX7 brakes in 2 lapping sessions at Laguna Seca Raceway last October I decided it was finally time to do something about the brakes. However, the last thing I want to do is buy a bunch of larger wheels and tires. My opinion is that the stock wheels and stock tire size is a great combination.

The only larger brake kit I found advertised that said it still fits under the stock wheels was the one put together by M2performance using Wilwood 6 Piston Front Calipers and 13" Brake Rotors.

I order this kit (with thermolock caliper piston and heat treated rotor option) from M2 Performance in late October. I finally got the last of the components (the front brake lines) last week. Yes, six months is absurd but that's another story...

On the plus side the quality of the kit looks great. But by eyeballing it I thought, "NO WAY this fits under the stock 16" rims!".

I finally test fitted the brakes today and amazingly they do fit with about 1mm to spare. Picture:

http://www.geocities.com/simplebond/M2Brakes.jpg

As you can see the 13" rotor is also much wider with a much greater vented area than the stock rotors. The caliper and pads are also much larger. I'm still suprised they fit under the stock wheel. M2 Performance says the whole kit weighs the same as the stock brakes. I havn't weighed them yet but judging by feel I'd say they're about the same weight. Pictures:

http://www.geocities.com/simplebond/M2Rotor.jpg http://www.geocities.com/simplebond/M2rotorside.jpg http://www.geocities.com/simplebond/M2Caliper.jpg

I decided it would be prudent to install some larger rear brakes also to try to balance things out. Since I still drive my car on the street I wanted to keep the stock parking brake so I decided to just go with the larger RZ '99 Model Brakes. Nobody seemed to have a clear answer if these fit under the stock 16" wheels. Some said yes and some said no. So I bought them and figured I'd take a gamble. The answer is yes, but with a minor modification. The knuckles on the back of the caliper barely drag against the inside of the stock wheel. I had to use the shadetree mechanic's favorite fabrication tool - the hand file - to take off a couple millimeters of metal on the end of the knuckles. Now it seems to barely fit. Pictures:

http://www.geocities.com/simplebond/rearbrakes.jpg http://www.geocities.com/simplebond/RearCaliper.jpg

I'm going to a three day track day and time trial at California Speedway in the middle of May so I'll let everyone know how they do on the track.

I am still waiting on some front brake ducts from the N-Tech group buy. I know Nick had some family emergencies that delayed things. Anyone know when he plans to ship them out?

I figure once I have this all done I should have the ultimate brakes that still fit under the stock wheels.

-John Magnuson
rx73rdgen@aol.com

Hey guys, Geocities won't let the links to the pictures above work but if you cut and paste the links into your web browser it will work.

What were you doing that you burn the stock brakes? Did you use DOT 4? and Performance Pads?

I was using Motul Brake Fluid and Porterfield R4 pads. I've had no problems with the combination on other tighter tracks. I think I just got over zealous braking into turn 2. Riding the ABS from 130 down to about 55 does wonders on your brakes. Of course I had no dedicated brake ducting. The the "ducts" from the R1 model lip.

You think if you had a brake duct and maybe some cool air going in that would have happened? BTW Whatd you kill the rotors or the caliper?

My guess is he was melting pads and cracking rotors. I've never used dedicated ducts on with stock rotors so I would be interested to hear how effective it is from someone who has. If you continually brake from 140 plus down to 55 with stock brakes my guess is your looking at some brake troubles no matter what kind of duct setup you have.

Why not? Calipers not big enough to disipitate the heat? Caliper not have enough grip?

Why not? Calipers not big enough to disipitate the heat? Caliper not have enough grip?

Well, to begin with my brakes started fading after just a couple of hard laps. During the third lapping session the brake fluid boiled over and I had massive fade. I also had about 1mm of brake pad material left on NEW PADS after 60 minutes of lapping. I didn't do a "break in" on the pad that time so that may be the cause of it. The rotors did not crack but the front rotors had some serious grooves and scoring.

May the Porterfield R1 pads aren't the way to go... who knows... I loved them on my Miata.

Like I said before this combo worked very well for me at Spring Mountain and Streets of Willows... but these tracks are easy on brakes.

But that's all beside the point now. We'll see how the M2 kit does!

-John

Well would a DOT 5 (non-silicone based) fix the boil over? Im doing Sebring at the end of July, and I heard that track is very tough on brakes, but I dont have the cash for upgrade.

John i thought you were selling your car? Its good to see that your not. I remember your outting with the Porsche club out in Nevada good luck and post your results with your new setup at Laguna Seca.

Yeah, I did intend to sell my car. I even got some nice offers. But I decided to keep it for a number of reasons. Plus, it's just so damn fun on a racetrack.

The stock FD are really quite nice. I'm not trying to say that they're bad or won't work fine in most situations if you prepare them right.

Anyway, I justed wanted everyone to know that the M2 13" brake kits does fit under the stock wheels. I'm going to a three day even in Fontana at California Speedway with the Porshe Club so I'll give a full report when it's done.

Ok so I wont post for a while, so I can read that whole thing ;). Thanks very interesting, halfway done with it. Probably will read it twice to make sure I understand it.

Too bad about M2. No way i'm waiting even six weeks for anyone's stuff. Think about how much money they're loosing from people who WANT to buy their stuff but won't put up with that. Sad.

Nice looking setup, and kudos to you for making the '99s work out back!

The GRM article is a decent summary of a variety of topics, but does not answer Fatman's "DOT 5?" question.

As I understand it, DOT 5 is silicone based, does not absorb water, and therefore may be a good choice for a restored classic or show car that is rarely driven. However, DOT 5 is not compatible with DOT 3 and/or 4, and can degrade seals, hoses, etc. In other words, you should bench flush your calipers, and perhaps rebuild them, if changing from DOT 3/4 to DOT 5 or vice versa.

Most OEM and race cars use DOT 3 or 4 brake fluid - these are petroleum-based, do absorb water, but are compatible with each other. The specs for the different fluids typically show their "dry" boiling point - their "wet" boiling point will obviously be lower. The main difference between DOT 3 and 4 is the boiling point - DOT 4 is higher. If you are putting your car on the track, you should be changing your brake fluid at least every 3 months anyway, so it's reasonable to just go with the highest "dry" boiling point you can find at a reasonable price. Beyond that, personal preference varies - Motul, ATE (clear or "Superblue"), Castrol SRF, Wilwood, AP, PFC - all have their proponents. I like the ATE fluids - I alternate between the clear and blue versions to make sure I've gotten a fairly complete flush.
Here's a nice comparison chart from Pegasus Racing: http://www.pegasusautoracing.com/pdfs/127.pdf

Mac daddy thanks that was a very helpful site. Actually I have found DOT 5 that are NOT silicone base MOTUL being one of them. I highly appreacite your input helps alot.

Hmmmm... the Motul Racing Brake Fluid bottle that I'm looking at right now which I purchased last weeks says DOT 4.

Typical Dry Boiling Point: 594 F (312 C)
Typical Wet Boiling Point: 421 F (216 C)

My understanding is that DOT 5 fluid is silicone based as a definintion? Does Motul make anther brake fluid that is DOT 5?

I think so, they make two though one silicone one not. Yet I may be off and maybe it wasnt Motul, cause I was looking into fluids since I will have to bleed mine anyways when I remove the ABS system to install the Garfinkle brace.

Since when do you have to remove the ABS to install the Garfinkle brace?

Thats what he told me =/

A thought about safety...

I was thinking about how I have about 3mm clearance between my brake calipers the insides of my wheels now. If I dent my wheel even slightly I think this could cause the wheel to hit the caliper and lock up the wheel? Or would it probably just break the caliper off? What do you think? Is this a dangerous set up?

-John Magnuson

I think you're fine. If you hit something hard enough to dent anything but the lip of the wheel (it's much harder to dent the entire wheel) then I think it would be the least of your worries as to whether the wheel locks due to striking the caliper.

should be more concerned with things heating up and rubbing. caliper gets hot and expands...wheel gets hot and expands...gap gets real small.

it won't ever jam...imho...but you could very well get some rubbing(grinding).

clearancing the calipers a TINY bit is usually ok...

john

Isnt the Brembos on the STI just about the same? Just like a few mm's away?

Yeah, some of the new cars I've seen seem to have almost no clearance between the wheels and brake calipers. The front M2 brakes seem to be ok as far as clearance even if they heat up and expand.

The rear RZ calipers I've already "clearanced" a little bit with Mr. Handfile. We'll see how they do when they get hot caues there is literally like 2mm clearance at most right now.

I just returned from a 3 day time trial at the California Speedway in Fontana, CA with the Porsche Club. We used about 2/3rds of the big oval and all the interior road course. It was a blast and my car performed very well. For the first time and had no engine temp or brake fade problems!

The M2/ Wilwood front brakes with N2 ducts combined with the RZ rear rotors worked very well. Absolutely no fade and rock solid performance even when I would stomp on the brakes from 130mph to 45mph. The track is well known for being a real brake killer (tons of long straights followed by tight turns) and the brakes worked great!

-John

Wow, interesting thread and lots of good info (Grass roots Link..must go read that now)

Thanks for the update John, glad your new brakes worked out well.

Just got back from my second event with these brakes at Buttonwillow. I guess I was too hard on the brakes because I had to bleed them after the third run session because they got mushy on me. I guess I can still manage to overtemp the fluid.

Of course the best solution is to not be so hard on the brakes... and I could also stand to have a large brake cooling duct inlet...

Any other suggestions? I don't think there is much more I can do than I already have:

13" front brakes with Wilwood Thermlock 6 Piston Calipers
N-tech brake duct
Rear RZ Brakes
Porterfield R4 pads
Motul Brake Fluid

I guess I could maybe go to a more aggessive pad? Do you think that would help? I havn't had any pad fade or melting problems... just my pedal gets squishy probably from boiling the brake fluid.

I presume you've got good air scoops in your front air dam and a fairly straight shot for your ducting to the N-tech plates? Motul is about as high a dry boiling point fluid as you can get - I presume you are flushing the system completely with new fluid before every track event?

If you are not threshold braking, doing so can help. It sounds counter-intuitive, but compressing your braking zone so that you have more time when you are not braking actually allows your rotors to dissipate the heat better. If you are threshold braking with the Porterfields, you are limited by tire traction, not brake pad/rotor friction, so a higher friction coefficient pad won't help. The main reason to go to a more aggressive pad would be if you were getting "pad fade" - which it doesn't sound like is the problem. That, and the "feel" - which has no impact on your brake overheating.

Brake later, brake harder, come off sooner, IOW use the tires more and the brakes less ;)

Thanks for the advise guys! Of course my driving ability still has a LONG was to go so I'll work on the later braking.

I would like to hear more on the solution that you employ. I would've thought that with the upgraded brakes/ducting and Motul fluid any brake problems would've been licked.

Please keep us posted with this thread.

-Mark

Im having some issues here. I was planing on upgrading my brakes, but decided to go with the OEM brakes. I just changed to Hawk Race brake pads and Brembo drilled and sloted discs.

Re-Amemiya did not change the original brakes until a few years ago, and there caars worked fine.

Here in norway, we don't have big enough tracks to go 140+mph.

I will be testing my new brakes out on june 22nd. When i will finaly be able to test my new setup. Then it will be only 18 days until my first race with the car :)

Can you expand more? Explain this a bit more.

They are saying instead of gradually braking and progressively going harder on the brakes over a longer period of time/distance.... to learn how to slam on the brakes in a short period of time/distance so that when you get off the brakes they have a longer time to cool.

I believe this is the interpretation.

-GNX7

Now that a think about it...

When I was a California Speedway it was basically a bunch of drag strips following by 180 turns (not the most fun track honestly) and I was slamming the brakes hard before each turn and then had a nice long drag strip to cool down. I had no problems there.

Buttonwillow is very curvy and there where a lot of places I was braking more frequently and sometimes more softly... trail braking and such. I suppose this contributed to my brake fluid boiling.

Yup - like I said, it's counter-intuitive, but braking longer and gentler actually builds up more heat in your brakes than threshold braking (braking at your tires' limit of adhesion). Assuming you're doing a driving school, not racing, you just pick a braking point that gives you a margin of error - how large a margin depends on conditions and your driving skill - and get on the brakes as hard as you can without locking them up. Then get off the brakes and back on the throttle. Remember - slow in, fast out is the quick way around the track!

If you're having to trail brake to rotate the car in anything other than really slow, tight corners, maybe you should set it up more "loose" - tending more towards oversteer. Depending on how what sort of suspension setup you have, you can increase the air pressure in your rear tires (only 1 or 2 psi at a time, please), stiffen the rear shocks, stiffen the rear sway bar, use the same size tires all around rather than max width rubber in the rear, etc.

Gaining speed is difficult so use your brakes as little as possible and when you need to use them use them fully. Don't just slam on them but Waltz ("Waltz" another Brad Barber term) into them hold on the edge of traction (threshold braking) Waltz right back out balancing the car on the release. If done correctly you should still be carrying enough speed upon turn it that the car is sliding slightly and you use the gas to maintain the balance all the way through the turn. If you don't brake enough you've lost time because you can't get back on the gas because you have to slide too much to scrub off more speed. If you brake too much your car is not at its traction limit and you've lost speed. If done perfectly your right at the limit with your car sliding just a little and as you immediately get back on the gas you throttle steer through the turn at the max speed with the car balanced. Can I do it? Rarely but its beautiful when I get it right.

That's the fun in it isn't it? Only the driver knows when he gets it perfect and the car pulls itself around the apex and tracks out perfectly without the driver doing anything but holding the throttle down :) I love that. It happens maybe once every other lap on a good day ;)

As for braking I tend to brake very late and very hard, release some pressure, turn in and always trailbrake into all but the slowest corners. Releasing the brakes is every bit as important as applying them; let the car come off the brakes gradually. In most cases the faster you're going the more time you need to spend letting it off the brakes. The car takes a moment to settle after every input you give it. Don't try to make it do too much at once.

Yeah... you guys have described what happens at every turn I take at the track pretty well ;)

In that case get some 19" wheels with 16" stop tech rotors mated to 6" brake ducts and keep doing what your doing or just slow the hell down :D

I revised and enlarged my brake duct inlets and my problems seem to be solved. I'll post pictures of my solution shortly.

Some pictures of the brake duct inlets:

That looks great John- Way to be innovative. I hope to employ something similar.

Going way back in this conversation. Dot 5.1 is compadible with dot 3/4

Actually I believe you have this backwards.

Yeah, my brakes agree with turbojeff. I get hotter brake temps by braking later and harder over a short distance than I do when braking a little earlier and making my braking distance longer. I figure the reason is time. When I stretch my braking over a longer period of time that leaves more time for the air to cool the rotors. The same amount of heat energy has to be removed in either case, but by braking over a longer distance that heat energy occurs over a longer time period and therefore the air has more time to remove it from the rotor.

Technical correction calipers dissapte the heat but very little, the heat is coming from the pads on the rotors, therefore those two experaince the most heat issues, the rotro accutally does most of the cooling job withen a disc system, the cooling fins helps alot, but the main factor is the caliper only covers a bit of the hwole rotor, so on the rest of the revoultion of the wheel and rotor the rotor has time to cool by the air passing by :) i'm not trying to be dumb or anything, just correcting misstakes if thats okay :P



Prôdigy

Does anybody know if a kit like this is avalible anywere? I want to keep stock size rims as I have a couple of sets of them. One has my R-compound set on them and I like to be able to keep using them.