Brake Setup on my Race Car
 

I recieved some PMs asking about the brake setup on my race car, so I decided to make this summary post.

First of all let me start by saying the brake system has gone through many iterations and probably will go through a few more over the next few race seasons. The changes I have gone through and things I have learned along the way is for another mind-numbing thread. This thread is meant to be a summary of my current setup rather that the long and painful history to get it to this point. ;-)

Basic Info:

Hydraulic System:
ABS totally removed (no abs)
Power Assist (brake booster) totally removed
Dual Master Cylinder Manual setup with Balance Bar
Remote Balance Bar adjustment

Brake Bias Gauge Setup:
SPA Digital Brake Bias Gauge with electronic inline sensors
(shows both front and rear line pressure or bias %)

Front Brakes:
Calipers = StopTech ST-40 (with custom piston sizes)
Rotors = StopTech 332x32mm
Pads = Hawk HT-14 Race HB141V.650
http://www.stoptech.com/

Rear Brakes:
Calipers = RacingBrake rear upgrade
Rotors = 322x20mm
Pads = Hawk HT-10 HB158.515
http://www.racingbrake.com/RX7_REAR_...2107-311-0.htm

Brake Ducting:
Custom made aluminum rotor seal plates and ducting. These were based off the ones I made out of carbon-fiber for the 'Big Red' setup I used to have up front (now on GooRoo's car).

Pics:

Manual System & Brake Bias Gauge Setup

http://www.myrx7.com/images/trackcar...s_manual_1.jpg

http://www.myrx7.com/images/trackcar...s_manual_2.jpg

http://www.myrx7.com/images/trackcar...s_manual_3.jpg

http://www.myrx7.com/images/trackcar...s_manual_4.jpg


Front Brakes

http://www.myrx7.com/images/trackcar...stoptech_5.jpg

Front Brake Ducting

I needed to make a new duct set for the front since the StopTechs have a larger inner diameter hole.

http://www.myrx7.com/images/trackcar...or_ducts_1.jpg

http://www.myrx7.com/images/trackcar...or_ducts_2.jpg

http://www.myrx7.com/images/trackcar...or_ducts_3.jpg

http://www.myrx7.com/images/trackcar...or_ducts_4.jpg

http://www.myrx7.com/images/trackcar...or_ducts_5.jpg


Rear Brakes

I really like the RacingBrake rear kit, the rotors are very impressive and their design keeps the temps very manageable with no ducting needed to the rear.

http://www.myrx7.com/images/trackcar...ar_brakes1.jpg


I do not have it working 100% the way I would like it yet, but I got it about 80% there...now its just tweaking to get the bias right.

I have a lot of people to thank that got me this far, thanks to:

- Andy (GooRoo) for being the brain behind the numbers of the setup and helping me with the redonkulous spreadsheets that calculated all the stuff I needed to know to get the brakes to where they should be with what we had to work with.

- Brand Barber, for a few fun phone conversations that helped me understand the system better (that is the dual MC system from his old track car, that was sold to fritz)

- Fritz, for sellin me the dual master setup :-)

- Howard Coleman, for his countless informative posts on many topics, including brakes.

- StopTech, for some very helpful phone calls and tech info on brakes setup.

- RaceingBrake, for making a very nice rear kit that balances a front upgrade.

- ProParts, for being my sales conduit to StopTech and dealing with crazy timeline requests.

- and... whoever else was there when i was tryin to get the brakes to work right and helped me bleed gallons of fuild through there ;-)

...any questions? :-)

Nice Damian, you gonna do a write up on this install

Id actually like to hear the whole "painfull history".

Itl give me a better idea and understanding on what to do with my brake setup.

so you are running a stop tech kit on the front and stock calipers with rear slotted rotors on the back?
i have a set of the stop techs aswell and have often wondered why i cant find em for the back? i guess they are not need cause 80% braking comes from the front??

so the slotted rear rotor are the same diameter a the stock ones?

The rears are stock calipers with a bracket made to use a super big rear rotor. Set up from Racing Brake.

That looks very nice

The painful part...... How Much?

Side note on the bias gauge setup:

I decided to pay a bit more and get an electronic setup that is based on inline sensors, rather than mechanical gagues. The reason is I did not want to run brakes lines into the cabin of the car to the mechanical gauges.

Thanks Damian for posting this thread so quickly!

Regards
Oliver

Damian, would you be willing to post piston sizes for everything? Also, how much additional leverage does Valskis' dual-MC mount provide over the stock pedal?

TIA.

I'll see if I can find the spread sheet that has all the data in it.

Damian's Piston sizes are listed in the thread below:

https://www.rx7club.com/showpost.php...postcount=1254

GooRoo - "3) Damian's Stoptech setup has custom 36/42 piston sizes and 13"x1.25" rotors"

Some more info for ya:

stoptech caliper piston sizes:
42mm and 36mm

stock rear caliper piston size:
35mm single piston calipers

predal ratio:
supposedly 7 from the documentation I have on the manual cage that connects to the stock pedal, however I am not 100% sure that is correct.

front
cp2623-92
(0.75") 3/4"

Master Cylinders:
front - AP Racing cp2623-92 (0.75") 3/4"
rear - AP Racing cp2623-92 (0.75") 3/4"
(I actualy changed the rear one at nasa nationals in between sessions, the origonal was a CP2623-90 (0.625") 5/8")

I am pretty sure there is another thread somewhere on brake setup that has GooRoo's spreadsheet and good info on what all the numbers mean and how they work together.

Find a similar set up like your design. This set up use a lot of stock parts, And is Bolt on too

piston size
F:3/4、R:13/16

http://revo-tune.jp/catalogue/img/70_0.jpg

Wow...........

Very cool find... looks like a nice setup too.

Does your car have the brake pad knock back problem. Or do you run the anti knock back springs.

Thanks for reminding me about that!!!

Yes, as my car got faster and was pulling more lateral Gs, I did get a bad pad knockback issue, so I did install the knockback springs and it basically removed the knockback problem.

Where did u find this? Is there more info about this setup?

I need to uppgrade my break master cylinder. And im looking for ideas how to do it.

JT

>>Where did u find this? Is there more info about this setup?

You can see the site its sold on here:
http://www.revo-tune.jp/catalogue/li...3S%29&s_md=and

>>I need to uppgrade my break master cylinder. And im looking for ideas how to do it.

Keep in mind this is not just a master cylinder upgrade, it is totaly different setup than stock, removing the power assist.

What is the difference between manual and power assist brake setups in terms of feel? What are the pros and cons of the manual setup?

Well, that is a very loaded question and could take a very lengthy in-depth explaination....but I will try to summ it up in a simple answer:

Simple Answer = better brake feel and balance ability

A manual system, with no Power assist, will typically give you much better pedal feel, since there it is only your foot making the pressure, and not a brake booster between you and the master cylinder, assiting you.

Also, a dual MC manual system allows you to use a balance bar and be able to set the bias of the front/rear braking...allowing you to maximize the braking for the cars setup and/or track and/or weather conditions, et, et.

Pros:
Great pedal feel
bias adjustable
if one line or MC fails, you still have one line with pressure
highly customizable with different MC sizes

Cons:
Not easy to get setup properly and you must match the entire system to have it work corretly, the MC sizes must match the caliper pistons sizes and the front/rear caliper piston sizes must be balanced right, et, et.


Keep in mind this is really meant to apply to race cars or cars that are tracked very often.... with my experience with it all, I would never do this to a street car or even a street car that sees some track time.... I would only do it to a full on race car or a car dedicated to a lot of track use.

So you don't have to tap up at all after corners with the springs?

yes and no :-)

let me clarify, I no longer have to 'pump' the pedal to get the pressure back, but I do still 'tap' for a brake check...they are 2 different things.

Before the knowback springs, I did have have to 'mini' pump once or twice to get the pedal back to the top with pressure, between very hard braking zones. That I no longer had to do after the knockback springs.

The brake 'tap' I still do as a brake check, to make sure i have pressure before i have to threshhold brake.

The thing is, as u upgrade your brake system with better components your knockback will increase, more rigid calipers and larger rotors will cause more 'deflection' that produces pad knockback.

Here is a great article on knockback:
http://www.stoptech.com/tech_info/wp_knockback.shtml

I love one of the listed solutions in that article, and the appropriate answer:

*****
5. Slow down and reduce cornering forces

Naturally, this solution is no fun and is not recommended.
*****

can you adjust the brake duct airflow so your pads can get to operation temps?
looks like they would stay to cold

Yup, we use a very complicated and technologically advanced system to manage the air flow to the brake ducts.... its called Duct Tape :-)



BTW, I use temp paint on the calipers, rotors, and pad backing plates, to review temps and make sure I am not below and not over the pads operating temp.

Simply awesome information! Thanks for sharing... now I want to rip up my 93 and build a track car :)

:-) thanks


I will be posting another thread soon on my solution to the dreaded 'oil catch can overflowing' problem that many track cars have. That is another system that I have batteled for years to get it right :-)

very nice!

hurry up and post that! :)

I'm working on that now in prep for this NASA season.

Gracias

Damian, nice scheming and putting it into function. Thanks for sharing.
Barry

Damian, I meant to ask if you knew what the bore size and stroke of your AP Master Cylinders were?

And also if you could shed some more light on the relationship between Master Cylinder bore sizes and the piston sizes of the calipers that would be great. You said this earlier, "you must match the entire system to have it work corretly, the MC sizes must match the caliper pistons sizes and the front/rear caliper piston sizes must be balanced right, et, et."

Greatly appreciated!
Charlie

>>Damian, I meant to ask if you knew what the bore size and stroke of your AP Master Cylinders were?

Already did, post #13 in this thread:
https://www.rx7club.com/showpost.php...2&postcount=13


>>And also if you could shed some more light on the relationship between Master Cylinder bore sizes and the piston sizes of the calipers that would be great. You said this earlier, "you must match the entire system to have it work corretly, the MC sizes must match the caliper pistons sizes and the front/rear caliper piston sizes must be balanced right, et, et."

wow, well this is a very loaded questions and would take a while to explain it all. I may have to save the details of this for another post :-)

If you check the other thread that has the spread sheet GooRoo made for use to help setup brake systems, you will see all the factors involved. Caliper piston sizes, rotor anulus area, pad friction coiffecient, car CG point, tires, master cylinder sizes, pedal mechanical advantage, power assist if you have it, et, et, et. Lots of variables,...

... but to simplify it, tires are what slow you down, and you are limited to the grip the tires can provide, from there, you want to maximize all 4 of your tires grip under braking, so you use the math to balance the components of the braking system to give you maximum front tire AND rear tire braking bias based on the cars weight transfer and other physics...that math will tell you how to setp the piston sizes and MC sizes, et.

Again, that is very oversimplified as we have not added in track conditions or heat management, et, et.

The biggest thing I learned was to not look at the brakes as individual parts, but as a system, and realize that its the system being in balance that will get the best performance.... as with anything on a performance car.

damian i know i'm not alone when i say how much i really appreciate you taking the time to share your knowledge and experience with the rest of us! you really are one of the best assets on this forum, and if i ever meet you in person i intend to buy you a sandwich. :) [/obsequious]

thanks :-)

I have a lot of great mentors helping me do a lot of this, they are the ones that deserve the credit.

Very nice setup.

agreed. I'll have to add this to my upgrade list.

One thing I forgot to add to the list and is very important:

Brake Knockback Springs!!!

After experiencing some very bad knockback during a few races, I installed the knockback springs and they solved the brake pedal problems from the knockback.

Nice thread :) :icon_tup:

Just wondering...any special reason why you opted for the Stoptech fronts over the Racing Brake fronts?

Thanks

Jon

The RacingBrake kit didn't exist at the time that we were troubleshooting his fronts. (Summer/Fall of '06) We had a 2-3 week window to fix the brakes (they were pretty bad) before the '06 NASA nationals. Stoptech tried to fit/send a custom kit to him in that timeframe. They didn't have the caliper mounting hardware in stock, so we tried to get something that would fit with the porsche 911TT (Big Red) caliper mounting hardware, and it was pretty close, but didn't work. So he just fit the Stoptech kit after the event when they could get the proper caliper mounting hardware.

Wonderful!

:-) neil

Usefull info. Where can I find brake duct inlets for the rotors?

Here are a coulple of pictures of my tilton dual MC brake set up:
https://i211.photobucket.com/albums/...D/LS1FD004.jpg
https://i211.photobucket.com/albums/...D/LS1FD018.jpg
https://i211.photobucket.com/albums/...D/LS1FD168.jpg

I'd prefer to do it the way Bill is doing it and keep ABS. Unfortunately, the cage that was in my car when I purchased it did not afford me that luxury. I guess I could look into placing it somewhere inside the compartment and building another bulkhead for it.

^Very niceeeee

opps, this was suppose to go in another thread. Sorry about that Damian.

Damián are you making any changes in your setup while you are doing your 20B swap?

This seems like a good thread in which to share this cool brake part from Iron Canyon Motorsports. It is a Brake Pressure sensor allowing you to get data on brake pressure and feed it into your data acquisition system. Originally designed for a Miata's brake system but should work on the RX7's brake system as well.

http://www.ironcanyonmotorsports.com...r-adapter.html

copy/paste:
An Iron Canyon Motorsports exclusive. We needed these for our cars and had a few extra manufactured in the process. Nobody but ICM has a 303 Stainless Steel banjo bolt with a 1/8 NPT fitting for a M10x1 threaded master cylinder. We know. We looked :). The ICM Brake Pressure Sender Adapter replaces an existing banjo bolt on the master cylinder and allows the use of a 1/8 NPT pressure sensor for measuring braking force. No cutting of critical brakelines or introduction of additional failure points in a critical system. Some are even drilling and tapping the master cylinder to install a sensor. As our class doesn't allow use of a proportioning valve you really only need to monitor a single point to pick up the brake pressure. Clean and easy.

Part 2 of this has been posted here:
https://www.rx7club.com/race-car-tec...t-2-a-1004164/

;-)