View Full Version : bbk porn

10-13-2010, 03:42 AM
I've been putting together a full brake system for my B5, and thought I'd share some pics this morning

Fronts are 13.5" (actually, 345mmx30mm)with 6 piston calipers, rears are 300mm with 4 piston calipers. I'm working on a pedal box which is very similar to Tilton's floor mount 3-pedal box (dual brake MC's/balance bar) since I don't pull enough vacuum to operate my power brake booster anyway.



as you might guess, I've used B6 S4 rotors, and after I recover from the initial expense of a complete brake system, I'll be changing these out for JHM 2pc rotors. The Wilwood calipers are so ridiculously light, that when holding these up for photos, it felt as though I was holding a model of a caliper or something. STUPID light... and we all know how light JHM 2pc rotors are, among all their other positive attributes...
I think these fill out the 18" wheels quite nicely, but the performance is what I am really anxious to find out about.

I have some stainless TFE hose and a mess of fittings on the way, so as soon as that package hits the front porch, I'll bed these in and get down to business.
The plan is to try 'em out on my stock booster/tandem MC, record data, then get the new pedalbox and master cylinders in, record, and compare.

The brackets used with thise mount them to factory B5 A4 knuckles, and use no carrier or any nonsense like that, rear is 1" 6061 front is 1.25" 6061 with a 3/8" steel plate on the inside.
the first set was a very long drawn out nightmare. -I can see why so few companies make BBK's for this platform.
I've made brackets for a few different cars in my time, and it's always been a simple measure, cut, punch a couple holes, bolt on and go... not quite so simple with this car!

A hydraulic hand brake will provide parking brake capabilities, as well as disengage traction control when activated, and re-engage traction control once deactivated (I think I just confused myself with that one) -basically, when I pull the handbrake, TC goes off so I can SLIDE, when I let go, TC comes back on and will theoretically straighten the car back out. -we'll have to see if it works as well as it looks on paper ;)

Does anyone know the cornerweights of a stock B5 A4? (approximately)
I've set my system up based on exactly what MY car weighs, and I'd like to know what a bone stock A4 weighs so I can compare my results with what I'd have done had this been an unmolested A4...

10-13-2010, 05:25 AM
I weighed my car awhile back and don't have access to the exact info right now, but I believe its about 800 lbs per front wheel, and about 750 per rear wheel. Front to rear ratio is around 60/40. I do remember the exact weight of my B5 was 3350 lbs with full spare and full tank of gas

10-13-2010, 07:47 AM
This is almost the exact system I have worked out in my head. Although with Cayenne Caliper and the exact same 2-PC rotors from JHM, 034 is selling this rear brake kit with an optional 2 Piece rotor, wondering if it can be upgraded to 325MM JHM 2-PC Rotors with a different bracket of course.

If you don't mind disclosing, what did you pay for the front calipers? And depending on that, would you mind fabricating an extra set of brackets for cash of course?

Also what caliper are you using for handbrake capabilities?

10-13-2010, 11:15 AM
found my scale photo.


10-13-2010, 03:07 PM
I'm planning on offering front, rear, front AND rear, and a COMPLETE brake system soon.

The Cayenne calipers are some really fantastic calipers, and I intended to use these for my fronts, along with JHM 2pc rotors, BUT! there were a few things which stopped me from doing so and caused me to go this route instead.
As I mentioned, Wilwood calipers are absurdly LIGHT. The 6 pot Cayenne Brembo's are not. Also, the JHM two piece -as well as any other like rotor you compare is going to be heavier in 350/355 x 32mm than it is in 345 x 30mm - by a couple pounds each! (remember, rotational mass has a much higher realized weight savings... shave 1lbs off each wheel, and that's like shedding 24lbs off thecar via non recip. weight!)
SPEC'S:piston sizes are very im portant. with the WW calipers, I was able to use exactly what I needed to build a properly balanced brake system without resorting to alternate pad compounds, proportioning valve, etc...

AVAILABILITY: B6 S4 rotors can be found at just about any auto parts store, anyplace thhat carries brake parts will have (or have access to these OEM rotors, + the pads are common size pads too
COST:These cost a LOT less than the 5mm larger x 2mm wider rotors

As for the rears, I can add 12.5mm radius to the mounting holes, but IMO, there's very little difference aesthetically and no need for the additional complexity in adding an obscure sized part to the mix. (God forbid JHM were to ever go out of business... where would you get replacement rotors!)

The corner weights are VERY close to what I weigh with my car. -despite the fact a lot has changed in mine!
Of course I'll have a HUGE range of adjustability once I switch over to the new pedals, manual brakes -w- dual masters and balance bar.for the relatively low cost, and ease of installation, I'd expect to see these going on most cars which have front and rear big Brakes, but I'd like to find out if the B6 S4 booster and master cyl. is different than thos used on B5 A4's?

By the way, Hydraulic handbrakes will work with anything. they're as "Universal" as it gets.

thanks for the info and scale photo

10-13-2010, 03:41 PM
Wow, this is great. Nice work. Would love to know what these components actually weigh individually compared to the stock stuff.

Just as a side thingy: Have you thought about the possibility of using an electric brake booster vacuum pump from a 2001.5 Tiptronic B5 A4, or a tiptronic B6 A4? Just something that came to mind when you mentioned the vacuum problem.

10-13-2010, 04:19 PM
Wow, this is great. Nice work. Would love to know what these components actually weigh individually compared to the stock stuff.

Just as a side thingy: Have you thought about the possibility of using an electric brake booster vacuum pump from a 2001.5 Tiptronic B5 A4, or a tiptronic B6 A4? Just something that came to mind when you mentioned the vacuum problem.
thanks for the suggestion, but I'm using this http://www.tiltonracing.com/images/3ped.jpg

besides the obvious, there are many reasons for using dual MC's, but here is a copy paste of Gorilla Performance's webpage for their BAL-BAR -very slick product and VERY knowledgeable guy who makes it. check it out here
Additional Information by special permission the information below was provided by Dean Oshiro and was originally posted on
the Mustang Forum:

The purpose of this Dual Master Cylinder setup is to get rid of the booster altogether because the engine does not produce the required amount of vacuum to operate the booster effectively. Here is a link about boosters to assist you: Boosters

Formula for Booster Pressure can be found here: Formula Booster

It takes about 1,000 psi to lock up your wheels, you need 1k psi by the master cylinder alone or the combination of a booster/master cylinder. The only thing that stops you from using a 3/4" bore "Tandem MC" is the fluid demand of the calipers. If you use a "Tandem MC" with too small of a bore the pedal travels a long ways and you might run out of brake fluid. If you put a large bore "Tandem MC" such as a 1 or 1-1/8 or even the 1-1/4 inch bore the pedal will be hard and will require a lot of foot pressure to stop the brakes.

To properly understand calipers here is a link that will assist you: Calipers

Here is a quick Formula on output pressure is different size master cylinders with a "6 to 1" pedal ratio. BEFORE you use this you need to calculate what your pedal ratio is. There are two types of brake pedals manual and power brake pedals. If you use the manual pedal with a booster/mc the brakes would be too sensitive; if you use the power pedal on without a booster the pedal will be too hard. Generally manual pedals are set up at 6.0 to 6.25 to 1 and power pedals are 5 to 1.

To calculate your pedal ratio use this formula: Pedal Ratio

On GM car they put two holes in the pedal, one for manual (upper hole) and one for power boosters (lower hole). If you will notice the GM cars have the booster tipped up in front and the booster bracket it at an angle. The reason for this is to point the booster rod to the lower hole of the GM brake pedal, to produce the manual ratio of 5:1. The advantage easy to change from manual to power brakes. The disadvantage is little or no hood clearance because the MC is close to the bottom of the hood and your reservoir volume is reduced because the fluid is tipped at an angle.

FMC did it correctly by using two pedals. Mustange owners all know what a pain it is in a 1967 Mustang to change to a power pedal. The 67 was the first year of this design so the upper bracket mount was not drill for both the manual and power pedal. Early cars only had the manual hole. Now you know why your booster master combination sits level in a FMC vs GMC.

Mustangs all have limited engine compartment space because of the shock towers and 428 even less. Now how many of us are running stock camshafts? How many have over 18 inches of vacuum to run a booster?

Ok, no vacuum so the booster does no good. Use a 7/8" or 1" master cylinder to get the pressure up. You have 764 and 998 psi with a 6:1 ratio pedal. Formula can be found here: Formula Master Cylinder Pressure

Advantage vs disadvantage is purely physics and math (assumptions: 6:1 pedal ratio, 100 psi applied foot pressure) :
1. A 1 inch MC manually has output pressure is 764 in order to lock up the brake you have to apply about 130 pounds of foot pressure to the pedal to produce 1,000 psi. Not very much for someone 250 lbs and 6-2 but what about the wife that is 110 lbs and 5-2? Or you 16 year old daughter that begged to take your car to the prom?
2. A 7/8 inch MC has a 998 psi, and you only have to apply 100 pounds to your pedal to lock up the brakes, GREAT! The disadvantage is pedal travel. When your pads are brand new with ZERO wear, the pedal will travel 130% further than the 1 inch master cylinder. Who cares? ..... the guy road racing and the guy that has 10k miles on his car with the pads almost wore down.

Unless you have actually raced (road race, auto ross, hill climbed, rally.....) a car, the hardest thing to do is braking and shifting in a corner. A pedal that travels too far complicates having to use the "heal and toe" method of brake/gas/clutch, almost impossible with a long stroke pedal. The racer's reading this can relate to the braking comparison of new pads vs worn out pads. Much easier with new pads, because of the pedal travel.

As your pads wear out with the Tandem MC setup your pedal travels further, until you have no pedal or not enough brake fluid. This is no problem for the more knowledgeable muscle car owner, he knows what the limits of his system is. The same knowledgeable owners forget that they are the smaller percentage of muscle car owners.

This is the most over looked factor when sizing your brake master cylinder effect pad use and safety. Piston travel and pad thickness is directly related to the MC bore size. For more information on calculating volume of master cylinder go to: Formula Master Cylinder Volume.

The advantage of the Dual Master cylinder is with a 3/4" bore the output pressure is 1400 psi and there is no wasted energy when using a balance bar. This is a copy of a link from the Brake Article on the internet and I quote (Dual MC's):

........."There are major advantages to using dual master cylinders: (1) Smaller diameter master cylinders can be used to increase output pressure. The design allows the application of two master cylinders being applied at the same, thereby doubling the volume output. Because of this high pressure output you will not need a vacuum booster. If you are running any type of camshaft, chances are you do not have enough vacuum to run the booster anyway. (2) The balance bar eliminates the use of a proportional valve and gives you the optional remote adjustment. (3) The remote fill applications deletes the need for residual valve normally used when the reservoirs are lower than the calipers.

When calculating the output pressure of each master cylinder you can not say that applied pressure is “shared” equally between the two (2) master cylinders. If the two master cylinders did not have a balance bar between them and the application of force was always equally distributed this statement would be true. The balance bar allows the applied pressure to be distributed unequally.


6:1 ratio pedal assembly
" master cylinders
Applied force of 100 pounds with your foot

The formula shows that this combination produces 1359 psi, however if you apply the 100 pounds of force to both of them equally it will only produce 50 percent or 679.5 psi.

What the balance bar allows you to do is apply 65% of the force to the front and 35% to the rear so the actual output pressures would be 883 & 475 psi.

This is how you are able to obtain maximum braking with the same amount of applied force. When you are using a tandem master cylinder (OEM type inline bore) the output pressure is equal in both ports and the only way to reduce the pressure to the rear braking system is through metering (distribution block, combination valve or engineering in the master cylinder) or proportional valve. This works fine when you have more than enough pressure with a power booster but when you are using a manual master cylinder this energy is “wasted”.

The easiest way to test this "wasted energy" is to apply 100 uniform pounds of pressure to a 6:1 pedal ratio and measure the pressure at the front calipers and the rear calipers with a pressure gauge. You will find that you will not have 763 psi you will have a reduced amount directly related to your proportioning or reduced pressure in the rear. If you reduce the pressure in the rear by 15% the out pressure in the front system will only have 648 psi at the gauge. The 648 psi is not taking into account "Friction Lost". Friction Lost is the amount of pressure lost from length of travel and the size of the piping.

The only way to know the effective actual output pressure of your system with a proportional valve or distribution block installed is to measure it with a pressure gauge when using a Tandem MC setup. You get 100% when you do not have this restriction on dual master cylinders. So how many pounds are you actually pushing with your foot when you use a Tandem MC?

The only disadvantage is higher cost..... but what is your car worth? What is your life worth?

Everybody has their own preferences, priorities, driving styles and disposable income (for our babies i.e. cars). Just give a formula or Physics reason why a Tandem MC works better than a Dual MC setup. FYI you can look in "Handbook of Physics" by Condon & Odishaw for any Physics rebuttal you might have. To an Engineer give him Physics and Math or give him a black and white answer, if you can't prove it on paper he won't believe you.

This setup is not for everybody, it is only another solution to no or little vacuum on the muscle cars we are building today. We did not have the horse power or speed 10, 20 or 30 years ago, so we did not need as much braking as we do now. With today's technology the sky is the limit and the only thing holding us from going faster is the tires, suspension and brakes not so much the engines. Band-aids like hydro-booster and vacuum canister/pumps are just one more thing to go wrong.

The above information provided through special permission by D. Oshiro.

and is posted here because I copy pasted this page:

10-13-2010, 05:06 PM
The front calipers are about 3.6lbs ea, the rear calipers are right at 3lbs ea and that's over-shooting the weights with my postage scale which leans on the heavy side so I don't F-myself when weighing things to ship... (add a little more weight with pads, but still STUPID light!

Now the 345/30 rotors have some weight to 'em, but not for long!
-JHM 2 piece rotors are the next nut to crack, and that's the nice thing about this system. you can start out with very inexpensive rotors, get the front AND rear brakes on the car, drive it while you save up an additional grand and change for the following:

Stock vs. JHM
-Rotor Weight: Stock = 25lbs(each), JHM = 15lbs(each) - 40% LIGHTER, 10lbs less each
-Rotor Cooling Air-gap: Stock = 9.5mm(.374"), JHM = 18.5mm(.728") - LARGER for better cooling
-Rotor Cooling Center Fin Design: Stock = Straight Fin, JHM = Airfoil - MORE EFFICIENT for better cooling
-Rotor OD: Stock = 345mm(13.6"), JHM = 345mm(13.6") - SAME
-Rotor Thickness: Stock = 30mm(1.18"), JHM = 30mm(1.18") - SAME
-Bolt pattern: - SAME (fits like an OEM rotor would)

Stock vs. JHM
-Rotor Weight: Stock = 12.5lbs(each), JHM = 9lbs(each) - 28% LIGHTER, 3.5lbs less each
-Rotor Cooling Air-gap: Stock = 8.5mm(.334"), JHM = 13mm(.511") - LARGER for better cooling
-Rotor Cooling Center Fin Design: Stock = Straight Fin, JHM = Airfoil - MORE EFFICIENT for better cooling
-Rotor OD: Stock = 300mm(11.8"), JHM = 300mm(11.8") - SAME
-Rotor Thickness: Stock = 22mm(.866"), JHM = 22mm(.866") - SAME
-Bolt pattern: - SAME (fits like an OEM rotor would)

that $1100 or whatever the rotors come to will shave almost .2 sec in the quarter. (27lbs off the wheels pays a 6 fold return in weight savings. that's almost 200lbs theoretical weight reduction, 100lbs= roughtly .1 sec 1/4m E.T. -it's almost 2 tenths off the quarter mile time, but since I'm already running 11 flat to 10.9's on turbo, and a tad bit faster with nitrous, I wouldn't expect THAT much on this car, but a reasonably modded car running say high 11's? -all day long...

I have DOT stainless brake lines which have AN3 at one end and the correct fitting at the other, so there's no F-ing around with a bunch of adapters... I see some "kits" -actually more than some, that sell you a -3straight to -3straight and a handful of adapters! what kind of crap is that?
I think inexpensive should not equal "low budget" right?

I've been a firm believer in Hawk Pads for many moons, but I have to say that I have good faith in the pads Wilwood makes/sells for their calipers, and am trying a set of BP10's, a set of BP20's, and of course will experiment with mixing the two for street and light track use.
we'll see... if they're not as impressive as the specifications promise, Hawk HP+ are some fine rotor eaters, but the WW pads are readily available as they're a popular WW size, and they're INEXPENSIVE (I paid 82/front and 51/rear for BP20 compound and a little less for BP10. try beating that with S4 and Cayenne combo brake pads! -it's not happening unless you're stealing them from somewhere...
I started a thread a little over than a week ago titled "ultimate BBK" something or another, but couldn't find it this morning. -However, I truly believe this is the hot setup in terms of price (both up front, maintenance and long term), performance, availability, versatility + they just look BITCHIN!
Oh, I failed to mention, these fit WELL within my 16lbs 18"x8" Kosei's and I have a feeling these would fit inside many 17" wheels. rears definitely, but fronts, I am PRETTY SURE. -will have to find someone closeby who has 17's for a test fit. bottom line is the calipers are sleek as can be and fit TIGHT to the rotors. If you look at the pics of the front wheel, realize that this is a 6 pot front caliper whic is over 9" long on a 13.58" rotor inside an 18" wheel
what do you guys think at first glance? should these fit with 17's?

10-13-2010, 05:15 PM

10-13-2010, 06:13 PM
Thanks for the props!
but Front + Rear BBK (calipers, rotors, brackets and DOT lines) all brand new, no refurbished or used shit, no home made parts (I'm working on a deal with a shop to CNC mill my brackets)
and I'm aiming for a price point that's close to a Cayenne BBK... -now that will be really cool!

The brackets are no joke... the material is expensive and the precision is very close tolerance. If I had to bill out my time for the first hand-made set at only $20/hr + material, the brackets alone would be close to $700 at this point! But once I'm only paying for a tooling setup and CAM shop time + bulk material, I think they'll be very VERY reasonable. -definitely the most challenging caliper brackets I have ever seen...As the saying goes: "The first one cost's a $million, and the millionth one costs $one" ;)

I'd like to know if anyone has EVER seen or heard of the actual knuckle/upright caliper mounting bosses failing, cracking, breaking, catching fire or exploding (ok, just kidding on the last couple!) but I would really like to know if anyone has ever come across this on any of these cars?
The uprights are cast pieces and they're VERY rugged as indicated by the Solidworks modeling and stress analysis I've done, Common sense takes a look at my bracket bolted to the upright and says "if it were to fail, it would break right there" [the upright's caliper boss]
Even the aluminum uprights I have (2001 S4) are terrifically durable -according to analysis, BUT, I'm more interested in real world results than theoretical and hypothetical stress modeling...

If this sounds appealing, please let me know, as I am considering becoming a paid advertiser here on AZ (if there's enough interest in these to go through with a CNC production run on the brackets, website development and proceeding with development of a few other models/platforms' brake upgrade systems

10-13-2010, 06:44 PM
LOL JK50, goodluck "selling" Ksport to Terra, he knows my luck with that company :O

10-13-2010, 06:44 PM
Wow. I just learned a lot about master cylinders. Thanks for the info JK35.

I very much like the focus on price here. The best setup for the money, with the option of going crazy at a later stage. And the weight savings are pretty excellent there. That's the first I've heard that your *brakes* can make you go faster, lol. So true though.

10-13-2010, 11:31 PM
I absolutely love the dual master cylinders! Excellent read. If you do become a seller, I am on the list. And I am still planning on going through you for an AEM standalone (which I will need more info on particulary for the 02 sensors in each exhaust runner before I get a manifold made), just gotta get rid of the $1500 of tickets I just got.

10-13-2010, 11:41 PM
Wow, thanks alot for the info man

10-14-2010, 06:57 PM
nice man. been looking into this lately. ill read full story tomorrow.