Yea yea, my description isn't exactly the best, but I didn't know of a better way to describe it. It can be seen in both of the following pics (the RE JGTC FD, and the Panspeed FD). I actually recently saw this on a fellow shopowner's FD, and I remember seeing a pic of it once here or there on the forum, but I never paid too much attention to it. All I remember was there was a ruckus made about it, how very few existed, and it was proported to be greatly advantageous. Anyone have any further info?

Thanks
~Ramy

 

It looks similar to other manual brakes setups I've seen on other "race" cars. Just no power assist via engine vacuum.

Here is a link where the pros and cons of manual brakes are dicussed pretty well.

https://www.rx7club.com/3rd-generation-specific-1993-2002-16/manual-brakes-brake-booster-removal-373165/

 

Any systems like that are NOT advantageous over the stock brakes with ABS. Those systems designed to achieve the best balanced braking (and variable) setups WITHOUT ABS -- in other words, they are designed for race cars. More specifically, they are designed for use in race cars in series that don't ALLOW ABS.

 

Those are dual brake master cylinders. One for front and other rear.

Jack

 

Running dual master cylinders is rare for the street/track day cars due to the benefits vs cost. however stating that they are only used when power assist and ABS are not allowed is incorrect....many GT cars in series like grand-am run a assisted dual setup w/ABS.

the reason for there use in race cars is due to there ability to fine tune brake bias via a bar connecting them together upon which is a pivot point which can be moved back and forth between the masters thusly changing the pressure applied to either the front or rear master

Tilton and AP are the most common brands

 

You are right...but the reason that such variability is required is due to the needs of setting up the car for different tracks/drivers. To run such a setup on anything other than a pure race car would be, IMO, silly.

 

rynberg,

silly would be an understatement. I was just pointing out that there use is not related to power assist or ABS

 

Rynberg, remember this thread: https://www.rx7club.com/3rd-generation-specific-1993-2002-16/big-brake-kits-retain-rear-parking-brake-539946/ and how you guys were saying that a lot of the big brake kits (fronts) mess up the brake bias? And hence most ppl stick w/ RZ rears? Well, if I understand correctly, wouldn't a dual master cylinder setup allow you to run the upgraded BBK of your choice yet maintain the correct/necessary/desired bias you're looking for?

~Ramy

 

That is a hell of a lot of difficulty, expense, and trouble when there are much easier solutions available! The Stoptech kit works with either stock or 99+ rear brakes. The AP kit has good bias with the 99+ rear brakes. Why bother with trying to reinvent the wheel?

 

1) It was a theoretical/hypothetical question. Wanted to know if I understood it's purpose and possible application.

2) You do realize that you're essentially limited to what works w/ the stock 99+ rears, right?

 

while i agree w Rynberg that a 2 resevoir adjustable bias braking system is not for 95% of FD owners IMO it is, hands down, the ultimate braking system for the street/track FD.

i ran the ABS on my car for the first few years w 18 X 8.5 fronts and 18 X10 rears w the M2 AP 4 piston fronts and never reached lockup running track events at Brainerd. during those 3 years i was never beaten... vipers, ferraris, corvettes, porsches etc.

i noticed my rear brakes weren't dusting the inner wheels so obviously they weren't doing the job. what was needed was to dial up the rears til just before the car becomes unstable under braking. and no, putting more brakes on the rear won't do it as you need to be able to adj the rears so as to reach just the right point...

i cannot over-emphasize the importance of being able to dial in as much rear brakes as possible so as to make time on a road course.

a significant part of the design of my last tube frame rx3 gt3 car related to increasing the effective rear braking effort. more rear weight ( my fd has 52% rear weight), rear suspension geometry... all to get more rear brakes.

the only way to achieve maximum braking is to be able to adjust the bias ideally from the cockpit.

as to streetcar adj brake bias...

we continually change our cars, tire selection, tire size, wheel size, springs, shocks, air pressure, summer, winter, rain, suspension settings, brake pads, calipers, ducting.
all these things require a twist of the bias dial.

for 95% of us the ABS will do just fine. for the other 5% a call to Tilton and some fabbing is in order.

howard coleman

 

If you don't even know what it is or how it works it's safe to say you don't need one. Oops. I forgot where I am. If you don't know what it is or how it works and have never seen one then it's an absolute must have mod

 

Just wait a few months, then we'll see a dual master cylinder look-alike on eBay that bolts in for appearance only.

Ramy is like me - just because something like this is far out racing equipment, doesn't mean I can't understand what it is, who uses it, and why. Good thread.

Howard, you HAVE in-car brake biasing - it's the big handle to the right of your shifter

Dave

 

Mark Valskis made a similar setup many years back. He made VERY few of the units, and they cost a fortune. Carlos has one on his car - came with the car, since it's Mark's old car .

Pics in this thread -

https://www.rx7club.com/showthread.p...3&page=2&pp=15

This is also one of those things that's VERY difficult to set up right. You just can't buy a master cylinder and go. Mark was/is an engineer for Brembo and put a lot of engineering into that setup. Brake systems that aren't set up properly can be a HUGE safety issue.

Agreed, this is very much a track setup thing - way out of the league of a street car. Heck, most big brake kits aren't needed on a street car either.

Dale

 

Howard, thanks for chiming in. Am I understanding correctly that this setup actually comes w/ a dial on the interior that allows you to change and adjust the bias on the fly? That's awesome.

Damon, I don't think this is a "cool" mod. Knowing what it is and how it works allows me to better understand if/why I need it - as I'm currently building my FD up for track use. And like Dave said, there's nothing wrong w/ seeking knowledge. For some of you, the forum is primarily a place where you exchange ideas. For others like myself, it's a huge learning tool. Let a brotha learn, k?

Dale, THAT'S it... Mark Valskis' part. I recently saw another track monster which had it.

~Ramy

 

Sorry if I came off with an attitude, Ramy. It just seems like people go way overboard with these cars on silly things, and that's where I was coming from. This is a good thread...

 

interesting thread. I still have ABS, stock brakes with HAWK pads and Ate Super Blue fluid...I'm yet to ride in a car that has more braking power than my car, even FD's with upgraded brakes...mainly due to the owner doesn't have the knowledge to set it up correctly.

Properly working FD brakes are amazing. I am still in the 95%

 

Tyler, it's cool. You've been a wee bit edgy lately...I hope all's alright

dubulup, I've heard *many* track junkies clearly state that the stock brakes are simply *not* up to the task of being tracked. They'll heatfade very quickly.

 

Some thoughts here.

Philosophically, the balance bar is the best mechanical solution for adjusting brake bias between the front and rear. Today's modern cars acheive far superior performance with electronically adjustable systems, but most race cars today use the same mechanical balance bar setup that's been around for decades.

However, these systems are notoriously hard to set up and suffer from a lot of problems in a street car environment. I built a system like this for a friend's 240Z and getting the balance right was challenging to say the least. Furthmore, balance bars have parts that need to be cleaned and serviced on a regular basis. I've seen very exhaustive analysis of these systems on very, very high performance race cars and they are not a simple as they seem.

If you want to keep the ABS and the factory in-line dual master setup, then a bias valve is a fine solution. From a design perspective, it's a good idea to overprovision the rear brakes and turn those down with the valve. Unfortunately, most streetable setups feature the '99 RZ brakes which are much smaller than a 13" or 14" front kit. So you have to put the bias valve on the fronts which is silly because you spend a ton of money putting 14" brakes and then you don't even use them to their full capacity.

This is where I'm stuck right now. I'd love to put a 6-pot AP caliper on a 14" rotor. I've seen this setup on M3 CSLs at the Nurburgring and they can run back-to-back laps on PS Cups with no problems whatsoever. But even with the RZ brakes, a 14" kit would push the bias WAY forward on the FD. To get the right balance, you'd need a valve...and then what's the point? Just run the 13" Stoptechs and be done with it.

I'm still looking for a kit that uses a fixed 4-pot caliper in the rear with a secondary mechanical spot caliper for the e-brake. That would allow a 6-pot 14" up front which would be great. But if I can't find that in the next 2-3 months, I'm going with Stoptechs with N-tech ducts and RZ rears.

-ch

 

we all are looking for different things from our fds...

as i previously posted the stock, or near stock brakes should work for 95% of us. that said the fd brakes on a road circuit w decent tires are gone in 2 laps. the car just doesn't have enough front rotor mass to absorb the heat.

you can just put a nice Coleman 13 inch rotor on the front and adapt the excellent fd caliper and you will notice a huge difference.

i run 4 piston lockheed AP CP5200 calipers upfront w a 13 inch rotor and don't even need front brake ducts. i run Brainerd Int'l Raceway and turn 3 is a 3rd gear tight corner that i am looking at going over 150 mph. absolutely no problem.

except my rear brakes are barely working. i junked the ABS and need to dial up the rears. i don't need larger rears as they do little work except contibuting to the longitudinal dynamic balance but it is extremely important to be able to use as much rear brakes as possible.

that's where Tilton's adj balance bar enters the picture. i have raced w it for somewhere around 15 seasons and have found it to be essential to get just the right amount of rear brakes... which is as much as possible without spinning the car. i have found it simple to adjust and trouble free.... sure clean and lubricate it every now and then. just a word of caution... while it might look simple to roll your own i strongly suggest you buy the real thing from Tilton. the braking system is not something to skimp on and no one makes it like Ed.

i look forward to fabbing it into my street/track fd.

howard coleman