Which master cylinder?

[ClayBelt]

I’ve got a 86 SVO that I’m in the process of slapping 03-04 Cobra front brakes on, and I was wondering what master cylinder I’ll want to use on my car with those and the stock rear brakes. Someone said the SVO’s 1 1/8” master would be too stiff to be practical, but I just want to make sure I use the right parts.

[Two86fiveoh's]

Swap the cobra rear brakes on and use the Cobra master cylinder. Don't use the SVO's 1 1/8" master.

[ClayBelt]

What master cylinder would I want to use if I don’t want to change out the rear brakes though?

[ThunderStruck]

Not sure, but I used my 93GT Master with Disc/Drum brakes.
ed

[ClayBelt]

Not sure, but I used my 93GT Master with Disc/Drum brakes.
ed

SVO has rear discs as well, otherwise I would

[ClayBelt]

I managed to get ahold of a couple SVO owners this morning who had done the 13” cobra fronts, SVO rears. They all reused the stock MC, so I guess I’ll try that and if it’s too firm I’ll just step down to a 95 GT then a LTC if that one still doesn’t feel right.

[erratic50]

You are playing with fire here. SVO had a vastly different brake design than other cars. Huge piston calipers with a large bore master cylinder.

if you switch designs in front, you have to in the rear as well and you don’t need to move as much fluid anymore.

Source the smaller diameter Lincoln rear calipers that fit the SVO brackets in back.

Get an M1858 master cylinder. 1” bore. Use the stock booster

[ClayBelt]

You are playing with fire here. SVO had a vastly different brake design than other cars. Huge piston calipers with a large bore master cylinder.

if you switch designs in front, you have to in the rear as well and you don’t need to move as much fluid anymore.

Source the smaller diameter Lincoln rear calipers that fit the SVO brackets in back.

Get an M1858 master cylinder. 1” bore. Use the stock booster

How is it playing with fire to put a larger rotor and dual piston calipers in place of a smaller rotor and (admittedly large) single piston caliper?

[Two86fiveoh's]

Calculate the volume of the front brake calipers. In my case, going from a 60mm single piston caliper to 38mm twins actually required less volume.

Replace the rear calipers with the Cobra calipers, run a Cobra master cylinder with an adjustable proportioning valve and you will have a brake setup that will work well. The volume of fluid needed will be spot on. It's not much more work to do it right.

[Patrick Olsen]

You are playing with fire here. SVO had a vastly different brake design than other cars. Huge piston calipers with a large bore master cylinder.

if you switch designs in front, you have to in the rear as well and you don’t need to move as much fluid anymore.

How is it "playing with fire"? The brakes will work, he's just have a firmer pedal, which he is already aware of, and knows what he need to do if he finds it objectionable. Some people like that firm pedal; apparently, there are other SVO owners who have done what he's doing and they haven't found it to be an issue.

Replace the rear calipers with the Cobra calipers, run a Cobra master cylinder with an adjustable proportioning valve and you will have a brake setup that will work well. The volume of fluid needed will be spot on. It's not much more work to do it right.

Except that he can't just replace the SVO calipers with Cobra calipers, because the SVO uses different length axles than either the Fox or SN95, so the '93 Cobra calipers won't line up with the rotors. And even if they did, the '93 Cobra calipers (designed to fit on 10.1" rotors) won't fit over the SVO's 11.3" rotors.

[erratic50]

It is easy to get the caliper volumes and therefore proportioning messed up to the point that it’s not within range to use an adjustable proportioning valve to fix it.

That is what I meant by playing with fire.

There are brackets available for normal fox width rear axles with SVO rear calipers. Those plus [87-93 V8 front spindles] or [82-83 continental / 84-86 SVO spindles with SN95 balljoints and MM SN95 to SVO adapters] and 73 MM SVO front calipers with a 1 1/8” SVO master cylinder is a good working combo

There are options with rear Lincoln calipers and SN95 front calipers with a 1” bore master cyl that are within adjustable range as well

Many other combos too.

[ClayBelt]

If it does in fact turn out to be unbearable to rock the Cobra fronts and SVO rears, it’s not like I don’t have options. The Mk VII had a 45mm rear caliper in its later years I could bolt in place of the 54m SVO one, which isn’t far off the Cobra’s 38mm. That swap should make the adjustability better if it comes down to it. Likewise if the pedal is unbearable there’s the 95 GT and LTC master cylinders I could try as well.

[Str8sixfan]

If it does in fact turn out to be unbearable to rock the Cobra fronts and SVO rears, it’s not like I don’t have options. The Mk VII had a 45mm rear caliper in its later years I could bolt in place of the 54m SVO one, which isn’t far off the Cobra’s 38mm. That swap should make the adjustability better if it comes down to it. Likewise if the pedal is unbearable there’s the 95 GT and LTC master cylinders I could try as well.

91-92 switched to the 45mm calipers on the Mark VII rear end you are correct. I don't believe however that the caliper mounting points between the early years Mark VIIs and late year Mark VIIs are necessarily in the same place because two different manufacturers made the caliper. But I don't know that answer for certain.

93 Cobra shared the 45mm Varga style rear caliper with the Mark VII. 38mm Varga caliper is SN95 issue. Iwasn't sure exactly how you were qualifying "cobra" so thought I would add this in as additional info. Maybe you were meaning SN95 Cobra when you said that. Self admittedly I only read the last two posts in detail.

[ClayBelt]

91-92 switched to the 45mm calipers on the Mark VII rear end you are correct. I don't believe however that the caliper mounting points between the early years Mark VIIs and late year Mark VIIs are necessarily in the same place because two different manufacturers made the caliper. But I don't know that answer for certain.

93 Cobra shared the 45mm Varga style rear caliper with the Mark VII. 38mm Varga caliper is SN95 issue. Iwasn't sure exactly how you were qualifying "cobra" so thought I would add this in as additional info. Maybe you were meaning SN95 Cobra when you said that. Self admittedly I only read the last two posts in detail.

One of the other guys was telling me to swap to SN95 cobra rears as well since I’m doing Termi front brakes, figured I wouldn’t be able to adjust that braking difference out. Since I don’t want to do a **** ton of work back there if it comes down to it I’ll probably try the Mk VII 91-92 rears rather than do a whole conversion if I can help it