Thanks for the info. Wilwood told me their manual setup put equal pressure front and back. Anyhow I am going to put the booster in today, I hope then mock up the MC so I can see how to a new fuel line into the rails and hopefully not have to move the clutch reservoir as well. :bang: :bang: :bang:

Despite what Wilwood said...
 

Here it is in Wilwood spec sheet in the link below:

"The stroke is set at 1.10” with a volume ratio of 2:1 between the primary and secondary chambers"

http://www.wilwood.com/mastercylinde...temno=260-9439

Semper Fi !

NOW the sales pitch LOL
 

If you still can't find your happiness after this next wave of mods, give us a call as we can make that bad boy stop like a fighter jet being snatched up by a tail hook coming in for a landing on an aircraft carrier. (Interestingly mentioned to us by a few actual fighter pilot customers running our systems in their muscle cars over the years).

Study all of the firewall and steering column support structure mods, and also your clutch MC positioning. If it's going to be the surgery I believe it will be to install the vacuum booster, you may as well strongly consider our bolt in special manual to power brake conversion package to save you all of the hassle. It is as slender as the master cylinder is on the engine side, clears all known clutch combinations, and in your application would bolt down from the engine side of the firewall as a true plug n play without any mods at all what so ever.

As a general rule, manual brakes will typically provide 700-1000 PSI of line pressure. A factory C3 vacuum booster will typically add a couple / three hundred PSI to that (given high levels of engine vacuum feeding it). If you have chosen to obtain and install a "mini booster" you will find exactly that: "mini boost" output. By comparison, our hydraulic assist system will *****cat around at normal stock type levels during regular driving maneuvers, but is capable of easily punching out 1600 - 1800 PSI on demand when called upon, "stopping you on a dime and giving you two nickels change"!

:popcorn2:

Wouldn't a 2:1 ratio be 66.6% / 33.3% instead of 72/25? Thus closer to the original ratio you quoted?

Regardless, that is interesting information. Do you know if other aftermarket MC's are also built this way? I use a GM unit, but it's good knowledge to have for the future...

Thanx!

Most all aftermarket MC's
 

I have found that most all aftermarket MC's are typically C3 Vette MC's in disguise (once torn down and carefully scrutinized). My math? Ok, it is my kryptonite, and good lord it looks like I'm wrong. Many many years ago (about twenty or so), I burette tested the CC outputs of various MC's x 1" of exact input stroke and got into all kinds of math... Over the next further years I actually didn't particularly chuck the math, but instead went into real world testing (less some of the math) Tobin at Kore3 is my go to guy for math these days LOL (caliper piston sizes x MC bore size x mechanical pedal leverage) The variable output of the hydroboost unit's can't seem to be exactly calculated though due to other variables such as PS pump max relief pressures and such. I have found that an installation with a Wilwood MC of exact same bore size (Wil-260-8856 with 1.125" bore) versus a C3 Vette MC (with the same 1.125" bore size)(as a back to back swap out) required considerably different inline adjustable proportioning valve settings. With the Wilwood in place, we could run the adjustable prop valve just about wide open (knob screwed all the way in), while swapping in the C3 Vette MC required considerable pressure reduction adjustments to the rear brakes = my type of real world "math" indicating a higher rear port / rear brake output with the C3 Vette MC as compared to the Wilwood. Hmmm...

As a tail hooker myself I understand the I hope I locked my harness before the cable stops me on the carrier. Thankfully flying harriers on the ship it was better to stop and land. I might give you a tomorrow as the booster is not going to fit as nicely as I thought it might. I am running the LS3 with the C4 rack and pinion.

My experience with a Wilwood master would lead me to the same conclusion. I had my proportioning valve wide open except for at time when I had an aggressive autocross pad on the rear. With a Hawk HP Plus or other less aggressive street pad, I always felt like I could use a little more rear brake.

With that being said, the car stopped very well with a manual 1" bore and I had 335mm R888's out back so they needed way more brake than the average car. The pedal effort was pretty firm.

Here are the details of the C3 manual brake conversion system
 

Click on this link for an expanded view:

http://www.hydratechbraking.com/images/3007.jpg

Take a good close look for reference. You will see I have designed this particular system to place the brake assist unit on center with the top two mounting points where your master cylinder is currently mounted. The C3 factory manual brake master cylinder design has two studs protruding from the firewall with the MC hole in the firewall on center of these two bolts, so the top two holes in the billet mounting plate on this brake unit will fasten there to the factory MC studs. Now 2.885" lower from the top two master cylinder mounting points are two 5/16" bolts going into your firewall / steering column support structure. This is where the lower two fastener points are in this manual to power brake conversion system. This system is angled downward just enough to stay out of hood clearance issues. This system is actually vastly easier to install than the poor guys that have a factory power brake system, as they have to fight four vacuum booster mounting nuts out from under the dash to unbolt the booster (then schedule a chiropractic appointment the day after). By contrast, you get to hit "the big red easy button" as all of your work is going to be pleasant because everything bolts from the engine compartment side nice and clean and simple. The only under dash diving you will have to do is establish the connection to the brake pedal (with this system providing a design that allows you set the brake pedal height wherever you may want it by spinning the brake assist unit's brake pedal rod in or out of the horseshoe clevis). This system will also have you use your existing manual brake connection point on the pedal, so you will definitely have to go with the larger 1.125" bore MC (Wilwood 260-8556P or Wilwood 260-8556BK) if you want to go that route. Or? We have a few other MC's you could look at available through us. Note that we do outsource the Wilwood MC's for customers upon request as needed, matching Summit Racing's Pricing at $239.95:

https://www.summitracing.com/parts/wil-260-8556p

https://www.summitracing.com/parts/wil-260-8556-bk

http://www.hydratechbraking.com/mastercylinders.html

Your LS3 pump and C4 rack are a very popular proven combination, so this will also be simple to connect the PS plumbing. Here is a general schematic of the plumbing for basic reference (courtesy of Concept One):

http://www.hydratechbraking.com/images/PShoserouting.JPG

Here is the hose assembly tutorial:

http://www.hydratechbraking.com/hosetech.html

For advanced system installation reading (note that "Photobucket ransom" has caused many images to no longer appear):

http://www.pro-touring.com/threads/8...es-w-Hydratech

Also, scroll down to the bottom of this (old) web page to see the C3 Vette feedback:

http://hydratechbraking.com/testimonials_old/

We also have three different levels of preparation available - scroll further down this web page to see the details and expandable photography:

http://www.hydratechbraking.com/products.html

I suggest you give my guy Jim Petty a call to discuss:

http://www.hydratechbraking.com/contact.html

I apologize, but I am not available for telephone calls (just way too much going on during the day to get involved with 15 - 45 minute phone calls (which is why I have Jim Petty). I have sent him a link to this forum discussion so that he knows what we have been talking about.

There IS a difference – Thank you for choosing Hydratech!

Thanks

I had nothing but trouble with my 7/8" Wilwood set-up also.......couldn't get any pressure or fluid flow to the rears........Bought another master and the same issue.......(these were probably the masters in the recall).....Bought a Detroit Speed power set-up and 15 minutes later my brake issues were gone.....Just Say'in.....

Ken