Manual brakes/brake booster removal?
 

Ok, since I've been inspired by the Valspeed brake kit which had a sweet AP dual cylinder setup and balance bar that completely replaced the brake booster and stock cylinder I've been dreaming of it ever since. Well, it's no longer in production and if it were I wouldn't pay $1,500 for it anyway, but I'd like to have a similar setup using similar components.
Has anyone else done this? What parts have you used? I think an off the shelf Wilwood dual master cylinder setup would work, what other parts should I look into?

Like this.
http://scuderiaciriani.com/scuderia/master.jpg
http://scuderiaciriani.com/scuderia/master2.jpg

https://www.rx7club.com/attachment.p...chmentid=81314

Not that difficult to make, when you've got the dimensions for the bracket handy. :)

Ah Jim, I was hoping you would chime in! What exactly are the dimensions of the bracket? :)
Would the Wilwood cylinders work with the same bracket? Feel like making a run of some for us??? :D

I've talked to Mark Valaskis (sp?) about brakes before. Some people have those Valspeed master cyl that shouldn't...

Make SURE you size the master cyl for what type of brakes you are using. It isn't just a simple bolt-on mod. If you just remove the booster you could end up with less brake force than you started with.

Mark works/worked for a premier brake manufacturer so he knows his brakes better than anyone here.

Anyone in particular? I've talked with Mark Valskis about his dual master cylinder conversion kit several times myself.

The master cylinders should be able to move enough fluid to fully depress the brake pistons. It would be wise to add an additional safety margin to that. Depending on which brake pistons you're using (stock or various aftermarket), you will have different needs as far as system capacity goes.

There are plenty of calculations that can and should be performed, and frankly I'm not familiar enough with them to be giving advice on which ones you should use. The books "Engineer to Win" by Carroll Smith and "Race Car Vehicle Dynamics" by Milliken might have brief sections on brake design. I know there are some books specifically written about braking systems, but I can't think of them off the top of my head. They are probably by European authors, those guys place a lot more importance on braking than most Americans do.


A quick and dirty real-world test would be to try and lock up all 4 tires. If you can do this, then your brakes are adequate. If not, back to the drawing board...

Note that it's a much better idea to properly design your braking system in the first place than to just throw parts on there and hope that it works. At the very least I would make absolutely sure that your new system moves an equal or greater amount of fluid vs. the stock Master Cylinder.

-s-

It isn't nearly that simple. The difference in bore sizes of the master(s) compared to the calipers is going to determine how much pedal pressure needs to be generated for a given clamping force along with how much pedal travel there is. There is also the difference in mechancial advantage between the brake pedal and the masters due to the pivoting balance bar.

If someone knows the piston diameters of the masters that are pictured you could safely substitute a different cylinder of the same diameter if you're also using it with the same type of calipers the system was setup for. This also assumes you know what the motion ratio of the pivoting balance bar is between the brake pedal and the cylinders and are fully capable of designing and building a proper bracket to hold it all together. The bracket and balance bar assembly are the keys to the entire system and there is much more thought put into them than most realize.

Going to dual masters with a balance bar is not something I would recommend to anyone but track racers. There is absolutely no reason for it on the street and if it's self engineered it will most definitely be screwed up. At the very least few people understand how to properly adjust the balance bar and I gurantee even fewer know how the hell a rear brake proportioning valve really works.

Put building brake systems up there with engine tuning. There are many people who have the ability to makes changes and maybe even build stuff but very, very few honestly understand what the hell they are doing. I'd find one of the Valspeed kits and buy it, other than that I wouldn't attempt it. People are going to come out of the woodwork explaining how easy it will be and they won't know what they're talking about.

I agree with Damon. Brakes are one of those things where an error in engineering can literally kill you. It's even trickier than tuning an engine IMHO, since engine tuning is pretty well documented, and brake system design really isn't.

I'd tap out all the well-explored upgrade paths first - stainless braided lines, 929 master cylinder, etc.

Dale

Doesn't really matter does it?

The 929 master cylinder isn't an upgrade for stock brakes. It has a larger bore diameter and will result in a higher brake pedal force for the same clamping force to the calipers.

The 929 master cylinder is commonly used on cars that have upgraded brakes w/larger pistons in the calipers. Larger pistons require more fluid to move the same distance, they also have more surface area so the same fluid pressure will result in more clamping force. So IF the front brakes have larger pistons you might need the 929 master cylinder to reduce the pedal travel.

Keep in mind brakes are a system and should be designed as such.

Glass Man,

First I suggest letting us know what problem your having with the stock brakes. Stock brakes are pretty good, upgraded pads do wonders for brake performance. On the street they are all you'll ever need. On the track they will work fine until you get pretty fast. At that point there are several upgraded kits to go with, one of them is a factory 99 setup.

Glassman,
The willwoods are too long, they wont fit. They will hit the shock tower. Only the AP cylinders or maybe Girling will fit. Oh, and possibly the new tilton short style cylinders.
1R1

I've got a 929 master cylinder and 99 spec brakes (2 piece rotors) with SS lines already. I really don't like the power/abs brakes while tracking the car. I started off with without abs and threshold braking years ago, and guess I just prefer the modulation and feel that manual brakes provide.
I guess I could look into getting the 99 spec abs controller, maybe that would help some?

Ah OK.

Well I'm not sure on if the 99+ ABS controller will fit a 93-94 FD. I know Mazda changed the ABS pump style in 95, I don't know if the 99+ cars have yet a different ABS pump and/or wiring to the controller in the rear.

Does a 95 ABS unit bolt-in/plug-in to a 93-94 car? Is it the same as a 99+ car?

A-spec offers "custom" master cylinders. Go on their web site under braking components, and then click on A-Spec Tuning. The picture they list on the page looks to be the same one as above.

The ABS unit changed mid-year in 1993, again for '95, and again for '96. The '96 ABS works in a '95 car, but I can't speak for the backwards compatibility of a '95+ ABS in a '93 or '94 without looking at the wiring diagrams.

FD04-43-7A0C - 1993
FD04-43-7A0D - mid 1993-1994
FD31-43-7A0A - 1995
FD31-43-7A0B - late 1995/1996+

The fact that the original 1993 ABS unit listed in the microfiche has a suffix of "C" indicates that there may have been an "A" and "B" prior to that, which means even more changes. I don't have a part number for a 1999 unit, nor have I been able to confirm that there was a change for 1999, 4-channel or not.

I'm pretty sure, not positive that all of the pre-95 ABS pumps interchange. What I was trying to get at is that I'm not sure if the 95+ pumps interchange as far as plumbing, wiring, etc.

The changes in 93 are likely internal to the pump not external as far as wiring and plumbing.

I know the ABS ECU was upgraded in the later years as well. Maybe this would help with the larger brakes and tires?

There is indeed a 1999+ 4-channel ABS unit. I've seen 'em.

~Ramy

so any advantage to double masters as opposed to the booster setup.... besides removing the ugly thing and increasing fluid capacity (arguable)?

booster question
 

I have a SR20 in my FD, and I'd like to do something with the booster.. The manifold is about 1/4inch away from the booster.. Does anyone have reccomendations on what I should do? I was thinking about a full tilton floor mount pedal set up, but I'm still unsure on which brake system I will end up with..

Spacer using stock master?
 

I was looking at the honed developments kits, sadly nothing for the FC but they said for a Miata, so long as you upgrade the pads and rotors so something like hawk HPS then it has great brake feel and stopping power using the stock master cylinder. Does anyone have experience with something like that for FC?
Besides doing this, my only option is going to chasebays and I cannot afford that right now.
this will be temporary until I can afford the chase bags kit, I am just getting the car running, driving and stopping so I don’t have to keep pushing this thing around
https://cimg6.ibsrv.net/gimg/www.rx7...2c194661b8.png
https://cimg7.ibsrv.net/gimg/www.rx7...44cd18a38d.png

I went full idiot on my brake system. Here is what I did...
I wanted manual brakes, as mine is primarily a track car. I probably would have gone with a kit like the one shown above, but I didn't see that at the time. I went with a Tilton 600 series underfoot assembly. I might eventually move to an under-slung, OE style kit like the one above because my underfoot assembly raises my feet up and the footwell in the FD is already tight enough.
I wanted to use the stock FD calipers all the way around, as they are more than sufficient for my car weight (less than stock) and power (<400hp). I called Tilton, and they asked for details on the front and rear caliper pistons, vehicle weight, wheelbase, rotor diameter, and maybe a few other things I cannot remember. Anyway, for MY application, they sized me 5/8" bore MCs. I made all the brake hard lines myself, and tied it into the stock calipers. Using the right tools and fittings yielded me no issues, and the car stopped like a *dream!

* I could feel the exact point that the brakes would lock up, and brake feel was amazing. The only problem was that the pedal travel was a bit excessive, and I was unable to heel-toe with the setup. Since those first few track outings, I have switched to 3/4" bore MCs with the known trade-off of more effort and less travel. Basically, I have to push a bit harder. I haven't run track with this setup yet, but I expect it should be solid.

A couple of things I'll say for anyone considering this:

- If you've never done anything like this, I highly suggest working with someone who knows how to build brake systems. I'm a mechanical engineer, and I still called Tilton to size the MCs for me. Yes, there are some equations you need to determine the bore of the MC, but make sure you can find all the information needed - You'll need the CG of YOUR car and you may need to estimate if you cannot use instrumentation to determine that. Tilton made a close estimation based on the information I gave them and the initial results were perfect except for the brake travel issue.
- Realize that you may need to do some trial-and-error when it comes to the master cylinders.
- If you choose to run your own brake lines from your new MCs to your calipers, use good tools (I used the vice-mounted turret Eastwood brake flaring tool and bender tool) and brake lines and fittings (I used only Fedhill) - Bending and flaring brake lines is not quite as difficult as you may think but you will waste a bit during the learning process.
- Careful consideration is now necessary because you will no longer have a brake booster / ABS!
- Make sure you properly bench bleed the MCs before bleeding the full system - speaking of bleeding, realize that you'll need to bleed both front and rear, together, of one side of the car since you'll now have two MCs attached to the same pedal. I suggest speed bleeders all around during this modification.

My brake system has been solid, and I inspect everything regularly. So far, so good.

i have had manual brakes since '04 and love them.

really love them.

(pictured in post 3)

https://imagizer.imageshack.com/v2/1...924/6YHqzE.jpg

on the street and track.

brake bias is as important as brake capability. the balance bar makes it really easy to set front to rear bias. as easy as twisting a dial from the driver's seat..

going slow very quickly is as important to lap times as going fast very quickly yet it receives almost zero attention.

i recommend manual brakes for both street and track. brake pedal effort is very close to no different than powered brakes and is way more linear.

someone should make the mechanism...

the OE brakes were designed for street usage. swap in any set of pads you wish and the brakes will be not operable in 3 laps (if being used 10/10ths) as the front rotors lack proper mass.

without a doubt, the FD's highest and best usage is on a road course. add a set of real front rotors, a nice aftermarket 4 piston caliper (6 piston if you want to look good at the drive-in), a set of larger rear rotors (the rear caliper is just fine) and the manual brake mechanism and you now have a set of brakes that are up to the caliber of the supercar FD suspension.

To make sure i am reading this correctly, you connected 1 MC to the left front and rear together, and the other MC to the two right side calipers? I may be wrong, but i have never seen that before. Usually the fronts are tied to one MC, and the rears to the other.

Given that the front calipers usually have more and larger pistons than the rears, they need more fluid. Hence the balance bar in the original post - adjusts bias front and rear.

I have that Valspeed MC setup on my car. I considered something similar for when I added hydroboost power brakes to my '65 Land-Rover but decided to go to a balance valve instead - a little easier to adjust. (The valve is in front of the remote reservoirs.)


https://cimg5.ibsrv.net/gimg/www.rx7...a6fb6d5743.png