John Magnuson

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.

John Magnuson

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

Section8

iTrader: (6)

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.

John Magnuson

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.

macdaddy

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.

Fritz Flynn

iTrader: (263)

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

John Magnuson

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.

gnx7

iTrader: (10)

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

jantore

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

Fatman0203

Can you expand more? Explain this a bit more.

gnx7

iTrader: (10)

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

John Magnuson

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.

macdaddy

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.

Fritz Flynn

iTrader: (263)

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.

DamonB

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.

John Magnuson

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

Fritz Flynn

iTrader: (263)

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

John Magnuson

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

John Magnuson

Some pictures of the brake duct inlets:

gnx7

iTrader: (10)

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

CrackHeadMel

iTrader: (2)

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

turbojeff

iTrader: (30)

Actually I believe you have this backwards.

DamonB

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.

Prôdigy2nd

iTrader: (3)

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

SpeedracerRX7

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.