One of the best upgrades you can do to your focbody is upgrade the weak brakes they came with stock. There is a guy on Corral that goes by "Matt90GT" that has a site that provides some great information. He also supplies some of the odd parts needed for budget brake upgrades.
I have bought from him and all parts were great and the service and knowledge was very usefull. I'm currently running 73mm Lincoln calipers on the front with braded lines and stainless steel slides and T-Bird disks out back all pushed by a 1996 Mustang master cyclinder through a adjustable proportioning valve. UNBLIVEABLE difference. And I think the entire upgrade with all new parts cost me under $700. You can do it cheeper with used junkyard parts.
Here is some info from Matts site.
Master Cylinder Upgrades:
The stock master cylinders on the 87-93 Mustangs are marginal with just the install of larger front 73 calipers. The 3 port design is really to blame. If you swap to rear disc, then a new MC is needed! There are 4 common MC upgrades out there for the Mustangs: the Lincoln/SVO unit, the '94-98 GT unit, the '93 Cobra unit and the '94-95 Cobra units. Each is a 2 port MC, so a conversion will be needed but they are all different bore sizes. Which one is the correct unit for you? Read on:
Here is a more specific information on the master cylinders mentioned:
'84-86 SVO - 1 1/8" bore, old style aluminum reservoir unit. no low fluid sensor. This is the same as the 84-90 Lincoln Mark 7. The difference is usually the SVO is aluminum, and the Lincoln can be a cast iron unit. The aluminum is what you want to keep the weight down.
'93 Cobra - 1.00" bore
'94-98 V6/GT - 1 1/16" bore, stock plug in for the low fluid sensor
'94-95 Cobra - 15/16" bore, stock plug in for low fluid sensor. Ports are reversed thread sizes from V6/GT
'99 V6 - 1.00" bore. can be converted to work for the low fluid sensor on the fox3 cars
Low fluid sensor notes: The stock '87-93 master cylinder has a plastic reservoir with a low fluid indicator. The '93 Cobra and the '94-98 units all have this, but the SVO unit does not have this feature. You will lose the low fluid sensor if you use the SVO unit. This will not cause the dash light to stay on, just permanently off. For the E-Brake light on the dash to come on with the E-Brake, you need to make a jumper in the connection you just removed. Connect pins 2-3 (the 2 purple wires, not the black ground). Be sure to label the connection to know what it is for in the future. For the '93 Cobra and '94-98 units, it is a direct plug in.
Which Master Cylinder?: The SVO unit was a very popular swap until the '94-98 units came readily available. It is very inexpensive at $15 rebuilt and has a large bore. This works BEST with the larger caddy or Lincoln rear calipers or the front SVO 73mm calipers, and is the only setup I recommend with the SVO unit! Other setups will be too stiff for most with the stock brake booster and it will not have enough pressure. The best all around unit is the '93 Cobra with the 1" bore, but it is more rare and it cost more. So the '94-98 V6/GT MCs would be a better compromise for most everything but the Cobra or Brembo brakes. This is the unit that I recommend! The bore is smaller than the SVO but larger than the Cobra ones. Pedal will be like stock if you use the SN95 brakes, or SVO/Lincoln front brakes with rear drums. You can find these for about $25 used at yards with the reservoir included. If you are planning on running the Cobra or Brembo brakes, then I would suggest the '94-95 Cobra 15/16" MC with the stock booster. This will give you a pedal that is not to hard. The last consideration is the cam in the engine. I make my recommendations off a stock 87-95 cam. If you are running a larger cam with less vacuum at idle, either drop a size in the master cylinder bore or set up to the larger 94-95 brake boosters to compensate.
Which Master Cylinder to use on fox3 ('87-93) cars with SN95 brake parts:
Well since you are using the Sn95 parts, you should use a SN95 master cylinder as they are designed together from the factory. The '94-98 V6/GT master cylinder will bolt directly into the PV to MC fittings that you have! You just need to convert the 3rd port . You can do this with fittings under the proportioning valve to keep things clean! The low fluid sensor is even a direct plug in!
If you use the '94-95 Cobra master cylinder for a softer pedal feel, you will need to get 2 fittings to swap the lines on the master cylinder. The cobra has fittings that are the opposite of the v6/GTs so they did not get mixed up on the assembly line.
Now you need to convert the stock 3 port MC to the newer 2 port MC design. You can either purchase a 93 Cobra combination valve from Ford for about $60, or use a 3-2 port conversion kit. The 3-2 kits is a T fitting that screws into the bottom of the PV and has an adapter for the 3rd port! It will work with the the '94-98 V6/GT MC, the '99 V6 units, the '94-98 Cobra, and '93 Cobra MCs! This is very neat looking at I am selling them at $30.00+ shiping! 3-2 Port Conversion Products
The other option is to use the parts from a '94-present NON-ABS mustang or '79-86 Mustang. They have a large fitting and special nut that will screw into the back of the stock combination valve. You will have to cut your stock 3rd port line and double flare the brake line there. Be sure to not remove any of the shuttle valve parts in the rear of the combination valve if you go this route.
Master Cylinder Notes:
1. If you install a new MC or upgrade the calipers, you will need to adjust out the brake rod booster to take out the slack in the pedal; this is of course after being sure there is no air in the system. There will be about 1-2" of travel in the pedal that does not push on the MC bore. This is when you need to adjust out the booster. Adjust the brake booster rod out 1-1.5 turns. Click here for a diagram
2. If you plan to go to rear disc brakes, then the 2 port MC will be required along with the FMS M-2450-A plug and an adjustable proportioning valve.
3. For the 93 Cobra Mustang, you can keep the stock master cylinder and proportioning valve; just adjust out the brake booster rod 1.5 turns with the larger 73mm calipers. It will work great with the SN95 parts, adjust the booster as needed.
Manual Brake conversions:
When you are converting to manual brakes, you do not want to use a master cylinder with larger than a 1" bore. The pedal will be extremely hard. The 15/16" bore sizes are the most popular sized units for these conversions. You can use the 94-95 Cobra units for the Mustangs
2. Which Brake fluid to use?
This is a very good question. You first need to consider how brake fluid is rated. It is by the boiling point.
DOT 2 DOT 3 DOT4 DOT5 DOT 5.1
Dry Boiling Point 374 401 446 500 585
Wet Boiling Point 284 311 356 421
DOT 2 spec is for drum brakes and is obsolete.
DOT 3 and DOT 4 fluids are compatible with each other and may be interchanged or mixed with no ill effects. These are most commonly found and used.
DOT 5 (silicone brake fluid) should be avoided because it is not compatible with regular brake fluid, it traps air bubbles in the fluid when pouring which results in soft pedal feel, and moisture will pool in low areas like your calipers and encourage rapid corrosion.
Here is a page with info on different brake fluids: http://www.shotimes.com/SHO3brakefluid.html
The Castrol LMA is a easily found product. Prestone DOT 4 is also very common for me locally. I would use either one on a street car. Be sure to flush your brake fluid at least once a year!
3. Proportioning valve modifications:
The stock proportioning valve will need to be modified if you go to rear disc or to install an adjustable proportioning valve. You will need the FMS part: M-2450-A and an adjustable proportioning valve to complete the modification.
Why do you need to modify the valve? Because it is designed for the specific car and brakes that come with it off the assembly line. So if you change to different size brakes, you will need to change the front to rear bias via the proportioning valve. If you do not, then you will not get the most braking capability out of the car. Worst case scenario, you have too much rear bias and the car spins around when the brakes are applied. Not good on a rainy night!
Okay, so how do you "gut" this proportioning valve? You use a 13/16 wrench and take the front cap off of it. Be careful as once it is loosened, the spring will shoot it out! Then remove the spring, the spring seat and rod. You may need some needle nose pliers to remove the rod from the valve. Do NOT remove the rear spring and rod from the rear of the valve. If you do modify the rear of the valve to work like the FMS M2300K kit or tap the rear for the 3rd port, be sure to install the rod and spring back in there!
Once you are done modifying the stock valve, you need to install an adjustable unit. There are two kinds of adjustable units: knob style and lever style. The lever style is more designed for an in-car application so that you can adjust the bias as the tires and brakes wear down in a race. You want the knob style. To install it, remove the coupler along the passenger side firewall and replace that with the valve. [pic]
When you bleed the brakes, adjust the valve all the way in for the maximum rear pressure. Once done, adjust the valve all the way out, and then in 4 full turns for your initial setting. Adjust in 1 turn increments from there and then half turn increments to fine tune. You will feel the braking and the pedal differ as the bias is changed.
If you have a Sn95 PV, it will mount backwards in a fox3 car. You can remove the front internals and cap and transfer that to the fox3 combination valve and that will work to the Sn95 bias specs. This may not be the best bias for a fox3 car, but will work.
4. Brake Booster Upgrades:
Once you have the larger master cylinder on your Mustang, you may find that it takes more pressure on the pedal to lock up the brakes then you would like. First, check all the vacuum lines for dry rot, cracks or holes. Replace all hoses that look skeptical. This will restore the vacuum for the booster to work properly.
If that still does not help, then you can consider two options. The first being to change to a smaller master cylinder. The second it to upgrade the brake booster. The best and about only upgrade is the Cobra brake booster. If you have heard about the Cobra brake booster, the same unit in the Ford M2300K brake kit (same as 1994-1998 Mustang Cobra and 1993 & 1995 Cobra R), you probably have heard horror stories about installing the unit. You do NOT need to beat the strut tower to install this unit for most all installations. Remove the old unit and the lower hole in the firewall you need to elongate down about 1". This will allow the unit to slide right in!
Cost $100-200 depending on if it is reman or new. You may be able to find one from a person selling it from their M2300K kit for cheaper.