Dual master upgrade

[65Rob]

I have a 65 with stock power brakes and the Grenada front disc swap. I want to change to a dual master cylinder and would like to get one with a new booster.
I can't seem to find anything that is a power to power upgrade, just manual to power upgrade.

Any suggestions would be greatly appreciated

 

[wicked93gs]

Mustang: Canning the Fruit Jar

this article discusses a few options

Master Cylinder bore sizes?

Does anyone know of or have a list of master cylinder bore sizes? Most of the internet part sites do not tell you the bore size. I need to get a 7/8s or 15/16ths M/C for my 4 wheel disc car. And it needs to be one of the shorter-bodied ones (7-1/2" tip to stern) like the 96 V6 mustang one I...

www.vintage-mustang.com

and this thread discusses bore sizes in depth

You will also want to measure the space available since you have a power booster.

 

[65Rob]

I have a 65 with stock power brakes and the Grenada front disc swap. I want to change to a dual master cylinder and would like to get one with a new booster.
I can't seem to find anything that is a power to power upgrade, just manual to power upgrade.

Any suggestions would be greatly appreciated

I was thinking of a Willwood type setup not so much something for a newer car.
Also not sure what bore size I have, there's no need to change that. The car stops just fine but I would like the safety of a dual master.

 

[wicked93gs]

Well, the whole point of the bore size is so that you know what you have to start with...so anything you swap to you can make sure to retain the same size for the same pedal feel...but it goes beyond just bore, you have to take into account stroke as well. There is a formula you can use to calculate it all out...but in essence, all the listed master cylinders are the same stroke, just different bore...when you go to something aftermarket like Wilwood, you need to know the specs(for example, my Wilwood MC for the clutch is a .75" bore with a 1.1" stroke) it all translates into how much fluid it moves and how much clamping force is applied at the slave/wheel cylinder. This is why its recommended to stick to Ford parts...they didn't change the stroke, so if you match bores you will retain the same pedal feel and clamping force(in theory).

 

[65Rob]

How do you calculate bore size? I thought it would be pretty standard, factory power brake car has 1" bore for instance. I haven't found anything difinitive about that.
They make conversions and upgrades for everything, don't know why this is complicated? I did the Grenada disc brake swap way back because they didn't make conversation kits back then.

 

[wicked93gs]

Bore size isn't calculated, it is what it is for a given master cylinder...as is stroke. If you are buying a kit they will have done all the work for you in what it works with, but if you are just buying an individual aftermarket piece like a master cylinder, just check to be sure the bore and stroke is the same. If one or both are different, the pedal feel and travel will change.

 

[AlmostCoffee]

...Why wouldn’t a manual to power set up work for a power to power application? Different booster mounts or something?

 

[wicked93gs]

...Why wouldn’t a manual to power set up work for a power to power application? Different booster mounts or something?

Well, there are different booster mount patterns...but no, master cylinder mount patterns are the same. Generally speaking power brakes and manual brakes have a different bore size for the master cylinder. Swapping bore sizes will affect brake feel and travel, whether it goes from softer to harder or harder to softer will depend on which way you are talking about.

Brake Tech & FAQ - Mark Williams Enterprises, Inc

Mark Williams Enterprises is an industry leading manufacturer of drag race axles, drive shafts, brakes, modular rears, rear end housings, thirdmembers, and chassis components.

www.markwilliams.com

Here is a good link that explains it way better than I can. Essentially when talking bore size(with all else being the same, stroke, brake cylinders or pistons)...a larger bore(that what you currently have) will create a stiffer pedal with a shorter travel while a smaller bore will create a softer pedal with a longer travel.

 

[AlmostCoffee]

Well, there are different booster mount patterns...but no, master cylinder mount patterns are the same. Generally speaking power brakes and manual brakes have a different bore size for the master cylinder. Swapping bore sizes will affect brake feel and travel, whether it goes from softer to harder or harder to softer will depend on which way you are talking about.

Brake Tech & FAQ - Mark Williams Enterprises, Inc

Mark Williams Enterprises is an industry leading manufacturer of drag race axles, drive shafts, brakes, modular rears, rear end housings, thirdmembers, and chassis components.

www.markwilliams.com

Here is a good link that explains it way better than I can. Essentially when talking bore size(with all else being the same, stroke, brake cylinders or pistons)...a larger bore(that what you currently have) will create a stiffer pedal with a shorter travel while a smaller bore will create a softer pedal with a longer travel.

Yeah i'm aware of bore sizes for manual vs power cars, larger bore masters will push more fluid but will require more pedal effort due to the force being exerted over a wider surface area. I just wasn't sure why he wouldn't just buy any booster/MC set up with a 1" bore if he already has power in his car (as he is asking why nobody makes "power to power" upgrades). Was curious if the stock booster sat flat to the firewall and he didn't want to bend his lines or something, otherwise I would've just bought any power set up with a 1" bore. I have to imagine any proper fitting master cylinder would have stroke limited by pedal travel.

 

[wicked93gs]

Yeah i'm aware of bore sizes for manual vs power cars, larger bore masters will push more fluid but will require more pedal effort due to the force being exerted over a wider surface area. I just wasn't sure why he wouldn't just buy any booster/MC set up with a 1" bore if he already has power in his car (as he is asking why nobody makes "power to power" upgrades). Was curious if the stock booster sat flat to the firewall and he didn't want to bend his lines or something, otherwise I would've just bought any power set up with a 1" bore. I have to imagine any proper fitting master cylinder would have stroke limited by pedal travel.

Maybe, maybe not, depends on the pedal ratio there. Any 1" master cylinder "should" work for him...but we are making the assumption than some aftermarket cylinder doesn't have less stroke than stock, and while that is likely the case, its always worth comparing before you spend money...besides, Its not like a Wilwood master is any better function-wise than a Ford master. I use Wilwood mainly when OEMs dont make an equivalent...IE, clutch master cylinder, adjustable proportioning valve, etc. I tend to like OEM parts over aftermarket for certain things, unless they are obviously sub-par(like the new mustang plastic clutch master cylinders and lines...why in the world would you use a plastic clutch line when you know people are going to run headers in the general area?).

 

[65Rob]

I'm going to stick with the stock setup for now. I'm still wiring it and have lots left to do before I can drive it. I figure it's best to do the upgrade at the end in case it needs to be sent back.
It's a restomod type build so I was looking at Willwood as they look a bit more high tech.
I can't find anything about a direct swap by anybody that's done it with the same setup as I have.

 

[wicked93gs]

If its a direct fit Wilwood cylinder with a 1" bore I doubt you will have any issues at all...its only when you get in the "universal" stuff that things can go sideways.

 

[65Rob]

That sounds good. I'll call them and hopefully talk to someone there that can make sure I get what I need. Going to wait until I'm close to the end of the build.
Thanks for all your input!