master cylinder help - 69 with 4 wheel disc

[corpse]

I searched through alot of threads, but ran out of patience <g>

The brakes on the car are just about setup.. All 4 wheels have Wilwood 4 piston calipers.. The brake pedal goes mostly to the floor and barely stops. It doesn't feel spongy, so I don't believe it's air in the lines.

The car originally (when all was stock), was front disc and rear drum.

One person told me I need a smaller port in the m/c for the rear brakes to increase pressure, but that seems incorrect.. It would seem the bore needs to be larger to accommodate the more fluid that needs to be pushed into the calipers (8 pistons will no doubt use more brake fluid than 2 wheel cylinders).

Any suggestions on what m/c to go out and buy? Fitment is very tight, there's like 1/2" clearance between m/c and the shock tower.. I am trying to make this quick and painless, instead of dealing with more hard line..

Also, I have a wilwood prop valve installed inline (for the rears) which is mounted by the shifter.. How that is adjsuted doesn't really help the pedal, although it changes the pressure (I have a brake pressure gauge hooked up too to see the difference).

 

[TOM B]

You will need a larger bore MC to supply more fluid now that you also have rear disc. the lenth should be the same as you have now, look in the wilwood catalog

 

[12sec67]

you might even need a residual valve

 

[Rusty67]

you might even need a residual valve

You only need a 2psi residual pressure valve in a disc system if the MC is physically lower then the calipers.

If you are using the same MC that the car came with then you definately need a new one. Get a wilwood or maybe an SVO MC. The SVO has a massive bore. I think its 1 1/8". I have the SVO in my 67, pedal is rock hard and barely moves lol.

 

[corpse]

The only thing that concerns me that hopefully you can advise me on, is I would like a m/c that is about the same length (definitely not longer) than the stock one, and also with the lines on the same side (trying to avoid bending more lines)..

edits:
The Wilwood M/C seems too long.. If the m/c is even 1/2" longer than the stock one, it won't fit unless I ditch the power booster.

Surely one of you guys have installed something "plug n play" for 4 wheel disc???

 

[LMan]

As Rusty says, its tough to move a SVO MC without power assist. There are several latemodel Mustang MCs that have a 15/16" bore, which might be better. Here's a good site for info:

Improve your Braking! SN95Brakes.com

 

[corpse]

that snbrakes site is down, I'll check it later..

I would prefer to keep power brakes, I was just commenting that I can't use a m/c that is longer from flange to the opposite end, or it will hit the shock tower - only .25-.50" clearance..

Perhaps the solution is to remove the stock m/c and have a machine shop bore it out...

 

[bnickel]

an aerostar master would probably work for what you need and i believe the lines are on the correct side as well. you will probably have to grind a little off the snout of it but there's a lot of meat there to work with.

the stock 69 master has a 1" bore already IIRC so you probably need the bigger 1 1/8 bore size.

Classic Performance Products (CPP) has a really nice master that has dual port locations and i believe it also has a built in prop valve too. check it out

Disc Brake, Steering and Suspension Products for classic Chevy and Ford cars and trucks

 

[corpse]

Classic Performance Products (CPP) has a really nice master that has dual port locations and i believe it also has a built in prop valve too. check it out

That is a nice m/c, but it's 1" longer than stock, which makes it too long <sigh>

 

[Rusty67]

You may need to sacrifice and make new lines. There are too many MCs out there that have the ports facing the passenger side. Good luck trying to find something larger then 1" bore that have outlets on the drivers side.

 

[gsxrken]

I've been right where you are. Check this link out-
Master cylinder for 4 wheel disc brakes? - Vintage Mustang Forums

 

[bnickel]

That is a nice m/c, but it's 1" longer than stock, which makes it too long <sigh>

have you considered using a smaller booster? there are quite a few companies selling a smaller booster and BONUS most are also dual diaphragm units whereas the stock 69 booster is only a single diaphragm. dual diaphragm boosters are supposed to be better for 4 wheel discs also.

 

[Decurion]

The other thing Ive heard people using is a Corvette master, since theyve had 4 wheel disk with 4 piston calipers at all corners since 1965. The 60s master cylinder is what Ive heard people using, but I personally have not tried it, and Im not sure if they changed it in the 70s or not. The only modification I think needs to be done is to elongate the mounting holes, but Im not even sure if you need to do that or not.

 

[BarnStang]

We got the SVO MC in the kit we got for a 67 proj. WOuld not fit. We got the rear disc kit from directfitbrakes. Greg sent me a MC that fit, but, he only had one source for it (don't know who) and he had a lot of trouble getting whoever it was to shp the part, but it does fit.
Am now concerned after reading through the VMF thread and this one that the bowls will be too small-will run out of fluid when the pads wear down.
From the VMF thread, how much can you safely cut off the SVO MC? I would like to use this as a backup plan cause I don't know what the bore size is on this smaller MC he sent. May be the bore is too small as well, but if not, this MC may be aother alternative to getting the booster and MC to fit...
Disc Brake, Steering and Suspension Products for classic Chevy and Ford cars and trucks

 

[bnickel]

you might try to find the master cylinder from a 69 f-250 with disc brakes, this is what ford used on the T/A boss 302's, not sure if it will work with the booster or not, i can't find any dimensional specs on it anywhere but it looks very similar to a stock mustang master cylinder.

this master cylinder is listed as also fitting 68-75 F-250 and F-350. the Bendix part # is 11779. oh and the ports are on the correct side as well (driver side)

 

[Markus]

I use a wilwood 1 1/16 bore mc (#260-4893) with a fox booster and 4 wheel disk. There is about 1/4 inch space between the mc and the shock tower.
The pedal feel is firm and the car stops good.