A little Brake Plumbing Help
I’m using a firewall mount Master cyl. from a 97 Windstar (front Disc rear drum) My truck has front disc and rear drum.

Do I need to use residual valves??? (10lb. rear / 2lb front)???

Do I need to use a prop??? Valve??? And if yes, it goes inline of the rear brake line???

One finial question: I got the master cly so long ago.. I don't remember which of the line goes to the front or rear. Its a single plastic reservior so that don't help me. any help ?
I can go back to the salvage yard and check one out if I need to.

 

Mike ,..Don't quote me on this , but I think the residual valves are only needed when the master cyl is installed under the floor.
The proportioning valve will probably be required between the master cyl and the rear wheels only since your using a Disc/drum combo. I think it will add excitement later during the smoky burnout/brake test session...LoL!

 

Hey Mt54

I would suggest using the distribution valve that came with the master cylinder to start with and see how the brakes work. The bore of the wheel cylinders and the brake calipers in comparison to the originals will determine if you have touchy brakes or you have to stand on the peddle to get her to stop.

Usually the forward brake line port on a master cylinder is for the rear brakes. Residual valves "from what I have been told" are to keep the brake fluid from draining back into a master cylinder that is mounted below the wheel cylinders as in a frame mounted master.

Cyrus
_____________________
Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in sideways, thoroughly used, totally worn out and loudly proclaiming... HELL YEAH!!! What a trip!

 

You would definitly need a proportioning valve, ensure you get one for disc/drum brakes it possible I would get one from the same vehicle you got the M/C. I ran the line with the largest bore from the M/C to the front brakes & the other one to the rear brakes. The port. valve has one line for the rear & two lines for the front two however, since you have the plastic resevoir you may have to get a manual or check one while you are the salvage yard. The lines goes from the M/C to the port. valve then to the wheel cylinders. If you google Ford brake system you can get a few diaghrams of brake set-ups.

 

I used the master cylinder from a 95 T-bird and had to use a proportioning valve. You will most likely need one also. I got mine from Summit and considering how it helped me assemble the brake lines it was well worth it. it has the switch,wire harness and is adjustable.

 

Brakes are a pain! Since I've been studying conversions and brakes for quite a while now, I'm going to try and explain this a bit. A disc/ drum master cylinder will have a larger volume bowl for the disc (usually in front) and a smaller bowl for fluid in the rear. A true disc and drum master cylinder often has a residual value already built into the master cylinder for drum applications (10lbs). With the master cylinder on the firewall, you won't need additional residual in the line. When running disc brakes in the front and disc or drum in the rear, a proportioning valve should be used but is not really necessary if the brakes work fine. The proportioning valve regulates the amount of braking to the rear and is installed in the rear brake lines to the drum brakes. Some mount them up by the firewall for easy adjustment rather than underneath the car where you have to crawl underneath for adjustment. I recommend Wilwood products for proportioning valves.
Another factor you need to be aware of is the size of the piston on the MC. As a rule, a smaller piston 3/4" will produce more pressure but less volume. A piston which is 1.125 will have less pressure force when the pedal is depressed but more volume and is recommended with power brakes. Drum brakes in the rear do not need as much pressure and volume as disc brakes require, that is why disc brake fluid bowls are much larger than drum brakes. The 10lb residual valve is merely in the line or MC to keep 10lbs of pressure on the rear brakes. Otherwise the drums would retract too far and not work as effectively. The residuals will keep a firm pedal and keep the brake pads near the drum for stopping power. I'm not real familiar with your MC, but I would check on some stats on it prior to going through all the trouble of installing it and it work for your application. You mentioned it had one plastic bowl on it? I would get a dual master cylinder for safety reasons. Fluid is fed from separate bowls. If the rear gets a leak, you still have front brakes and vice versa. Most hotrodders I meet, go with the 67-69 Corvette master cylinder. That's what I'm running and I'm running four wheel discs right now. Hope this helps.

 

Thanks for the help guys.
As my memory slowly starts giving me small shots of what was on the Windstar when I removed the MC, I seem to recall it had no distribution valve. The lines from the MC went directly to the ABS block, then off to the individual wheels.
I picked this MC because it seemed to me the donor vehicle was similar in weight and it had the disc front, drum rear set up that I wanted.
I never really considered the dual chamber as being a problem since it was front disc and rear drum.
At this point I won’t say using a different MC is out of the question, however with all the work I have into fitting the pedal assy and this MC I really don’t want to change now.

If anyone has used one of these mid 90’s ford MC, and they all seem to fairly similar, with the dual lines and single plastic reservoir, any Info would be great.
Or if I knew how to get the pertinent information about this MC, so I could plumb it properly that would help.

 

I have determined that it is a 1.125" bore and piston

 

MT54- With that size bore and piston, you'll definity have to use power brakes with at least a 8" dual diaphram booster. As a rule also... The larger the bore and piston, the harder your pedal will feel. Depends on the ratio of your brake pedals also. Don't want to confuse you with info here, but if you choose that MC, get a booster to work with it. You'll be much happier.

 

Ed,
I got the whole assy. off the windstar, MC, Booster, and pedal assy. The booster is all of 8".
you think this should do the trick ?

 

Any other insight on this ?

 

Did the Windstar have a portportioning valve, on a lot od modern vehicles the valve is located under/inside the frame. If you got everything and are running the same brakes combination dsc/pads it should work.

 

I would say it should work, however there is a rule with brakes... They never work out perfectly. I would install what you got and see what happens. Once you have the main install done, it's fairly simple to change things, like a MC, etc.
Ed

 

Thanks for the info guys..
We'll give it a go

 

Mike

Just sent some info in a e-mail.