trainwreck517

iTrader: (1)

So how good is the stock brake system? I have heard many mix things. Some racers have told me with proper ducting and pads, they will survive most race conditions with a sub 350hp range and relative slow tracks (sub 140mph). Some have told me that the disk diameter and material isn’t enough, and that the brakes will cook up no matter what and that a brake disc upgrade is needed if any type of serious road racing / Time Trials is going to be taking place.
At my last track event I began to experience brake fade after about 4 laps of hard driving. I was running Hawk HP+ with stock ducts.

Bit info on the car during this event:
Street Ported 13B-REW with ~2300 miles
Greedy V-Spec FMIC
60-1 Turbo @ 10psi
275/30/R18 R-Compounds all the way around.


So being limited on funds, I went with adding some proper brake ducts to the front discs rather than a big brake kit.

So here is a walkthrough of my setup since I had a few friends ask for details, I figured I’d post it here for everyone to see and hopefully provide some feedback on my experience once I test it out at the track.

So here it goes:

• First I remove the wheel, brake caliper, stock brake duct and hub. Once the spindle is exposed, I cut the mounting ear towards the front of the car.


• I than made back plate out of cardboard to get the mounting holes and dimensions.


• I than went ahead and fabricated the black with aluminum.




• I than mocked up the duct with some cardboard.


• After which I modeled it so that I could get make the ducts out of sheet aluminum.



• I than mounted it up to my front bumper lip opening.

trainwreck517

iTrader: (1)

• I than routed the 3” duct hose.





• This is how it looks through at the front once painted black.




• And as an added bonus, here is my secret to keeping my coolant temperatures low when out on a track:

I made a custom under tray to create an extra opening for the radiator which bypasses the FMIC. This provides the Radiator with some much needed fresh air. Track temperatures usually hover around 87°C-92°C.


Most of this was made with hand tools, and scrap metal I got for free. So very little cost out of pocket but if one were to purchase the material I’d say you are looking at close to $30 worth of aluminum material + ~$50 for the duct so about $80 total.

So time to test out the system.
I have my next track outing on January 30th on the same track I experience brake fade on. I will first test the setup with the HP+ and 10psi of boost on the first session, which is the same setup I experienced brake fade on. If this holds up fine, I will crank up the boost to 12psi and keep the HP+ on for the second session. If the car feels good, and I don’t run into any problems, I plan on switching to Hawk DTC-60 in the front and Hawk DTC-30 in the rear and bring up the boost to 15psi.

At 15psi I should be near the 400hp, which is the setup I plan on racing in this year’s NASA TT season. I am hoping the higher temperature pads and ducts will be enough for the braking system.

I am still using the stock replacement Brembo rotors; however I plan on using the Racing Brake rotors once these rotors begin to wear out for added cooling (directional cooling vanes).

Let me know if there are any questions.

Thanks,
Alvaro G.

JhnRx7

iTrader: (12)

Very nice!

I also just did this with my stock brakes here. I see you cut off the third mounting point... really makes things easier giving you more room to weld in the hose inlet and gives you more inlet area to not restrict flow. I did not want to modify my hubs so my setup will be more restrictive and I had to get more creative with my inlet.

Any pictures of the backing plate all mounted up with the rotor from behind? I considered adding a lip to mine to extend inside the rotor, but just opted to keep the plate flat and bring it in really close to the rotor face.

Im looking forward to seeing your on track results. I wont be able to get my car on track until the springtime, so keep us updated

ptrhahn

iTrader: (9)

Nice work.

FYI, HP Plus's aren't going to work no matter what you duct them with though... you're going to need a true dedicated track pad.

Look into Hawk HT-10's, DTC-60's or DTC-70's... or stuff from other manufacturers like PFC 97's and 01's.

trainwreck517

iTrader: (1)

Thanks,

Yea getting the extender to stick to the back plate was a bit hard since I started to warp the aluminum. My machining / welding experience is all from High School metal shop from about 11 years ago, hehe. I'll post a picture of the back side of the rotor this weekend.

Your build up looks very nice! Are you worried the fiberglass will break off the aluminum back plate under high heat / stress conditions?


Thanks,
Like I said in my first post, I plan on running DTC-60 in the front with DTC-30 in rear. I just wanted to run HP+ to see how the additional cooling will affect the braking for a good before and after comparison.

OneRotor

iTrader: (3)

Maybe try a set of the Ti backing plates that GoodfellasFD3S just posted in his build thread? Are you having issues with brake pad material, boiling of fluid, or both?

trainwreck517

iTrader: (1)

I did not boil fluid, it was more of an issue of exceeding the pad material rating temperature. HP+ only rated for 800F.

DTC-60 and DTC-30 pads are rated at 1600F and 1300F, so I hope this will resolve any brake fading issue. However boiling of fluid might be an issue once the brake material begins to fade away. I will definitely look into the Ti brake pad shims if I begin bowling fluid once the pad wear down.

Thanks,
-Alavro

JhnRx7

iTrader: (12)

I was initially concerned about the fiberglass resin and the heat, but i did some research on the topic and found that it should not be much of an issue. I got a good quality 3M resin which is supposed to handle high temperatures well. After it was cured i stuck it in the oven and it seemed to do just fine. Also, they are not directly connected to the brake rotors so there will be no heat transfer due to conduction, only radiation. And when the brakes get their hottest there will be plenty of air flowing through the duct that will cool via convection and help keep heat away from the duct. The biggest issue is immediately after a session when the car is not moving.

As far as stress conditions, the only torque applied to the inlet is from the brake hose when turning the wheel. The hose is loose so the torque applied to it is VERY minimal. The fiberglass is very strong and is rivited to the backing plate as well as bolted to the hub via the third mounting hole. Shouldn't be an issue. We will see how it holds up once it gets warmer and I get the car on the track

trainwreck517

iTrader: (1)

I didn't see any rivets or that it was mounted to the spindle, I thought it was only the resin holding it in place to the back plate which I was concerned about. But with rivets and bolting it down to spindle, I agree that you shouldn't have any issues.

I also wanted to add that the pictures you took of your build up are very nice, I got lazy and just used my cell phone but after seeing your thread I wish I would have used my camera and lighting setup.

primerGrey

iTrader: (13)

This thread might have some useful info for you.

https://www.rx7club.com/showthread.p...58#post7450858

With the 1600 deg pads, you won't get fade at around 300 hp, but the pads wear out very fast (1-2 days for Carbotech XP10 pads). After going several years with ducted stock brakes I eventually built my own custom BBK using the same calipers (Outlaw) that Pettit was using in their first BBK. Total cost was about $600 bucks ($300 for each caliper), the brake bias is the same as stock, they fit under 16" wheels, and use 2002 Crown Vic front rotors that are about $30 each. The hard part was machining the caliper mounts. If you ever are interested I'd be happy to send you the drawings for the caliper mounts. Or you can spend more money and buy bigger wheels and get the stoptech kit - to me, that one looks like the nicest commercially available BBK for the track.

trainwreck517

iTrader: (1)

Well just wanted to give a quick update,

Rained in Jan 30th, so didn't take the car out on the track. But took the car out yesterday to streets of willow, I kept the HP+ pads and had no problem slowing down from 115mph -> ~40mph down the strait running CCW.

Though I'll admit, that after a few laps the the pads lost there "bite" however were still stopping the car great. There is no doubt in my mind that without the ducts, I would have cooked the brakes.

I planned to switched out my brakes to Hawk DTC-60 / DTC-30 for the final two sessions and bump up the boost to 12psi, but I developed a exhaust leak between the engine and manifold so called it a day after 3 sessions (still had to drive the car 100 miles back home).

Highest water temperature was 86°C.

Overall a I am very pleased with the performance of the brake ducts, and think it is a cheap mod that can greatly reduce the chances of getting brake fade on the stock brake system.

-Alvaro

Specter328

iTrader: (2)

What diameter are the ducted backing plates?

trainwreck517

iTrader: (1)

What ever the diameter is for the opening on the stock rotors. Sorry, didn't take any measurements.

Narfle

iTrader: (16)

I don't think those discs will hold up for track pads and large R-compound tires.

Ducting looks good.
Interested to see your results. Good luck.

trainwreck517

iTrader: (1)

Why won't the discs hold up? I am running Michelin Pilot Sport Cup R-compound tires, 285/30ZR18.

Even with the HP+ pads, I was able to engage the ABS a hand full of times at the track and stop power was great over all.

I have seen a few SCCA E-Production FC's running stock brakes with proper ducting and have no problems.

So just curious as to why you say the discs won't hold up?

I'll definitely update this thread once I put in the DTC-60 / DTC-30 combo and run higher boost.

Thanks,
-Alvaro

Andrew.

iTrader: (4)

Aren't E-Prod FC's NA? So I doubt they're making anything over 180rwhp, that + race tires = plenty enough for the stock system.

I'd like to see the results once you up the boost, but then again, you're going to be also getting a better pad.

Right now you're okay, because you have wide tires (improved braking) and less HP, but once you increase the HP (increase your straight line speed), you're going to feel the brake fade more.

I was at the absolute limit with the stock brakes in my FC with HP+ with 330hp and RA-1's, with ducting, but considering the FD has larger rotors, I would say that the limit with the FD and stock brakes is 350-380hp. I never bothered with stock brakes on the FD since I was planning on making over 450+hp, but if you're going to stay at 400hp, I'd say you're at the complete limits of the stock braking system, assuming you're an intermediate driver. There are cooling fans that run inside the ducts that further help dissipate the heat - you should look into that.

How were your lap times at SOWS? I'm hoping to crack the 1:23.XX barrier once I get the FD running again

trainwreck517

iTrader: (1)

Yea, E-Production is N/A.

Yea, I don't plan on pushing more then 350rwhp. At least for now anyways. So I hope the stock brake system holds up.

1:23? Now that's fast! I was 1:33 taking it easy. I planned to get more aggressive and start using 2nd gear for the final two sessions of the day ( was being lazy and just left in 3rd), but developed an exhaust leak between the block and the manifold so called it a day after 3 sessions (out of 5).

Then I almost lost it on the 4th lap of the 1st session, so became a bit more cautions since I still had to drive the car 110 miles back home.

http://www.youtube.com/watch?v=ew4i9vnh634

Let me know when you make out to the track Andrew, definitely would like to catch up and check out your car.

-Alvaro

Andrew.

iTrader: (4)

Alvaro, you need to take this line going through the bowl:



You can play with the braking zones, but you should be able to gain 2-4 (or even more!) seconds there from what I'm seeing in your video. You've left some time on the table in a few places.

My estimate is on fresh NT-01's, assuming I decide to bite the bullet and go the street-driven R-comp route. My other option is street tires, and if that's the case, I'll probably be in the 1:26 range.

trainwreck517

iTrader: (1)

Yea, I tried that line as well later in the day. But I'll admit, it just felt weird braking into the bowl rather then before it. So I only did it twice. I definitely plan on going back soon, so will play with that again.

Let me know when you make it out to the track, I'd would definitely like some pointers.

-Alvaro

trainwreck517

iTrader: (1)

So another update.

Ran Buttonwillow 13CW with DTC-60 in the front and DTC-30 in the rear. Brakes felt absolutely great the whole day. This will definitely be my brake pads of choice from now on.

Andrew.

iTrader: (4)

Awesome man! I'm guessing you ran in the Speed Ventures TA? How did you do? Crack that 2:00 barrier? I believe JC took 1st in his S2000 with a 1:56, right? Any other FD's out there? What were their times?

Narfle

iTrader: (16)

Because the extra rubber means you can brake a lot harder, and the extra power means you'll need to. The stock rotors weren't intended to cope with that type of heat for sustained periods. I think they'll warp or crack.

trainwreck517

iTrader: (1)

Sadly no, fastest was 2:14 w/ traffic @~8psi. I kept having problems with the car, so was never able to be out for more then 3-4 laps before something would break (Lost a coolant plug, IC coupler popped off, exhaust leak).


Didn't run the Time Attack on Sunday, just ran Saturday for the open track day to work out the kinks in the car.

No other FD's, a S5 FC and 3 RX-8's.

Quick video of 2:14 lap.. feedback welcomed:
http://www.youtube.com/watch?v=rMO80x3SRoo



I feel with proper cooling, they will work for my application (sub 350rwhp). However I will be sure to update this thread when I reach the limit of this setup.

fd_neal

iTrader: (4)

Ive cracked a few stock rotors, when they are WELL below minimum thickness.
I have 2 heavy braking zones at my track, one is 250 to 140kmph the other is 220 to 110kmph and when I ran hawk blues Id go through a set of rotors per set of pads and they would crack when worn past min thickness by a couple of mm, and the pads would start to fade at the 15minute mark of a session. I now run DTC 60 pads, no more rotor wear issues and havent cracked any rotors running the DTC60's yet, and no more brake fade. FWIW i have brake ducts that arent as nice as the OP's.

HotRodMex

iTrader: (3)

That was me. I kept meaning to go over and say hi, but my day didn't end up going like I wanted it to. It was good to not be the only RX7 there; I seem to have the worst luck with that.