Four Lug Disc Conversion?

[mustangxtreme]

Nice score. Congrats

[83Fox]

so after purchasing the cobra rear end i started gazing through my mustang parts catalogs. as i was looking through my LMR(late model restoration) catalog i came across a ford racing proportioning valve. part # m2328c for $49.99. i was wondering if this is going to work with my conversion. also is there any difference between the 84-86 svo master cylinder and the 1993 cobra master cylinder and which one would be best suited for my swap. i do have the 87-93 brake upgrade up front and a 1992 gt master(i believe) in her right now. also does anyone know of braided brake lines for the rear conversion? please let me know. thanks.

[qtrracer]

SVO M/C has an integrated reservoir (all cast piece) with a 1-1/8" piston. This M/C requires very large piston calipers such as the 73mm SVO front and 54mm rear. Generally too big for anything smaller like the 60mm 87-93 front stock caliper and 38mm Cobra rear caliper. Pedal will be very short and very hard. The 93 Cobra M/C has a plastic reservoir and a 1" piston; generally better suited to the common 4-wheel disc brake upgrade.

Manual proportioning valves typically come in two flavors: a knob style that one adjusts from the engine bay and a lever style that is generally used in the cabin and adjusted on track. I purchased a Wilwood knob style and inserted it at the junction on the P/S firewall.

[83Fox]

it would be the knob style. what would i have to do to adapt to the svo calipers up front?

[85GTVince]

qtrracer gave you some good advice. I will add that the preferred MC for a '79-'86 Mustang is the '85 Town Car MC. It has a 1" bore and it uses SAE fittings.


--Vince

[83Fox]

even if i have the 87-93 power brake booster? i just wanted to see if the 1993 cobra m/c would work. if i decide to go with the svo master then what would i need to do to convert to the bigger svo calipers

[85GTVince]

even if i have the 87-93 power brake booster? i just wanted to see if the 1993 cobra m/c would work. if i decide to go with the svo master then what would i need to do to convert to the bigger svo calipers

Personally, I would use the 1" MC with the stock '87-'93 booster. IMO, the '93 Cobra booster has too much boost and you end up with a soft pedal. Obviously, Ford designed and sold it that way so it is not "too" soft. It is just softer than I prefer in a "performance" car.

The '93 Cobra MC will work. It is a 1" MC. Functionally the '85 Town Car MC, the '93 Cobra MC, and the '99 V6 MC are all the same. The Town Car one has SAE fittings and it has an integral reservoir, where as the other two have metric fittings and a separate plastic reservoir. They all bolt up the same.

To use the SVO 1-1/8" MC you would need the 73mm SVO front calipers (which bolt right up to the '87-'93 V8 spindles) and the 54mm SVO rear calipers. In order to use the SVO rear calipers you will need SVO axles (they are 1.25" longer than stock Fox) and axle brackets (as well as pads, rotors, and hoses). You can use Fox length axles if you flip the brackets and mount them on the inside (if you don't mind a little fab work). Then when you are all done and have the SVO MC (and brakes) you have gained little to no braking performance. In fact, the braking performance may be worse because there are very few performance rear pads available for the SVO rear calipers. The only benefit is slightly better front pad wear (less taper) due to the larger piston area.

Good luck and let us know what you decide and how it turns out for you.


--Vince

[85GT-79FJ40]

Just looked at this thread after looking at the one about the cobra wheels. One thing that hasn't been addressed in this thread is that the 93 cobra rear is wider than a stock mustang rear. If i'm not mistaken it's identical to the 88 turbo coupe disc rear I have in my car. If you plan on running factory wheels it's fine and I actually like the wider stance. But larger 17 inch aftermarket wheels are going to get up close and personal with the rear fender lips.

[83Fox]

All good love the wider stance look. ill let you know what i decide to do

[85GTVince]

Just looked at this thread after looking at the one about the cobra wheels. One thing that hasn't been addressed in this thread is that the 93 cobra rear is wider than a stock mustang rear. If i'm not mistaken it's identical to the 88 turbo coupe disc rear I have in my car. If you plan on running factory wheels it's fine and I actually like the wider stance. But larger 17 inch aftermarket wheels are going to get up close and personal with the rear fender lips.

You are correct. The '93 Cobra axles and brakes are the same as the '87-'88 Turbo Coupe. The housings actually have one small difference; the TC housing has different quad shock mounts. From memory, the TC quad shock mounts are 1" (it may be 2") higher than the Mustang quad shock mounts.

It is the extra width (3/4" per side) that caused Ford to produce the '93 Cobra wheels with 3/4" more offset. Because they put 3/4" more offset in the wheels they made new front rotors with 3/4" taller hat section.


--Vince

[qtrracer]

While I like the extra rear track look, wouldn't this add rear grip to a car that typically has way too much understeer in the first place? If so, might be better to stay with the stock rear track unless you put some more grip up front.

[85GTVince]

Typically, if you are going to 5-lug the you will also be adding wider front wheels and tires than stock so it should not be a problem.

Fundamentally, you are correct. Widening the front track will add more front grip (less understeer and widening the rear track will add more rear grip (less oversteer). Of course I am referring to lateral grip not longitudinal grip.


--Vince