[Buckhr]

Ive got an '86 with the basic 5 lug conversion, front 11" discs w/ SN95 V6 spindles + calipers and rear drums. The BB is shot, and MC is just as old so want to replace both. I have been reading about brake booster and master cylinder upgrades with larger brakes + 5 lug, but based on my current setup and no near term plans to change I am wondering if anyone has recommendations on the best BB + MC combo for this setup?

I am considering just replacing with stock '86 components at the moment given the lack of difference from stock '86 setup.

Thanks for any input!

Current build status pics:

1 and 2

 

[kjb302ho]

i did a cobra booster on my 86 a few years ago along with a mc from a cobra. it worked well for 10 years.

i just did a hydro boost conversation using maximum Motorsports kit and a really nice used hydroboost set up from prestige mustang thst included unit and master cylinder.

blows the cobra set up out of the water. and the mm kit made it really easy. direct bolt in and fabed up my own ps hose for the hp side using ptfe hose and fittings.

 

[tony91723]

I also did a cobra booster and master cylinder combo. It was night and day difference from the stock parks.

 

[kjb302ho]

Ive got an '86 with the basic 5 lug conversion, front 11" discs w/ SN95 V6 spindles + calipers and rear drums. The BB is shot, and MC is just as old so want to replace both. I have been reading about brake booster and master cylinder upgrades with larger brakes + 5 lug, but based on my current setup and no near term plans to change I am wondering if anyone has recommendations on the best BB + MC combo for this setup?

I am considering just replacing with stock '86 components at the moment given the lack of difference from stock '86 setup.

Thanks for any input!

Current build status pics:

1 and 2

if there was a time to do anything, it would be now. if your doing a cobra set up, use the booster from a 93 cobra. i would suggest using a 93 cobra mc and start from there. if you want a harder pedal, go to a mc from a 99 v6 stang. if you want a softer pedal, 95 gt.

 

[90MarkVII]

i did a cobra booster on my 86 a few years ago along with a mc from a cobra. it worked well for 10 years.

i just did a hydro boost conversation using maximum Motorsports kit and a really nice used hydroboost set up from prestige mustang thst included unit and master cylinder.

blows the cobra set up out of the water. and the mm kit made it really easy. direct bolt in and fabed up my own ps hose for the hp side using ptfe hose and fittings.

Please check your messages.

 

[Buckhr]

I also did a cobra booster and master cylinder combo. It was night and day difference from the stock parks.

Did you also upgrade the brakes, larger fronts and/or discs in the rear?

 

[Buckhr]

if there was a time to do anything, it would be now. if your doing a cobra set up, use the booster from a 93 cobra. i would suggest using a 93 cobra mc and start from there. if you want a harder pedal, go to a mc from a 99 v6 stang. if you want a softer pedal, 95 gt.

I am not moving to cobra setup right now. I may upgrade later, but I have higher priorities right now. I am looking for advise on what BB + MC to use with this setup.

 

[kjb302ho]

93 cobra booster and 93 Cobra mc. there you go.

 

[tony91723]

Did you also upgrade the brakes, larger fronts and/or discs in the rear?

Yes I run 94 cobra calipers and 03/04 rotors with a complete sn95 rear end. I have the bigger rear cobra brake kit sitting in my garage waiting to be installed. For now though these brakes do just fine. I did gut the proportioning valve and installed an adjustable one near the passenger hood hinge. There is a fitting that can be removed and replaced with the adjustable proportioning valve.

 

[Mustang5L5]

Which front SN95 disk do you actually have? the 94-98 66mm single piston units, or the 99-04 dual piston units?

With the rear drums, you really want to be careful about MC selection and not compare your car to the setups where guys are running rear disks. There is a little math behind the choice that will maintain proper pedal stroke ratio and feel. Unfortunately, changing brakes while leaving the rear drums doesn't make things easy.

I can show math here, but long story short, with the rear drums, your best choice is a stock MC. Pedal feel will be closest to stock with the 99-04 2-piston units as they are the closest of the two 11" SN95 setups to the stock 60mm calipers in terms of piston surface area, and a little bit softer with the 94-98 66mm calipers. Ideally, a 7/8" bore MC would probably be as "big" as you want to go here, but i'm not aware of one that will bolt on the 86 style Booster.

Don't compare your setup to setups with rear disk brakes. It's apples to oranges and you cannot go by why those setups use. Rear drum wheel cylinders have very small surface area compared to rear calipers, so that's why the stock MC is so small. The stock MC is roughly 0.83" in OD. Changing from that to a 1.00" OD bores is a HUGE jump. You're pedal stroke will be short, and leg effort will be very high. The larger OD you go, the more fluid you can move per linear inch of stroke, which means actual travel distance will go down.

When you decide to change your brake setup, then change the parts to match.

I wouldn't change the booster either. Your new calipers have a larger surface area compared to the old 60mm units you replaced. That fact alone, with the stock MC, means you will have reduced pedal effort and more hydraulic advantage. I would not put a cobra booster on. You're brakes will feel VERY over-assisted.

TL;DR: Stay with stock MC and booster for now.

 

[Buckhr]

Which front SN95 disk do you actually have? the 94-98 66mm single piston units, or the 99-04 dual piston units?

With the rear drums, you really want to be careful about MC selection and not compare your car to the setups where guys are running rear disks. There is a little math behind the choice that will maintain proper pedal stroke ratio and feel. Unfortunately, changing brakes while leaving the rear drums doesn't make things easy.

I can show math here, but long story short, with the rear drums, your best choice is a stock MC. Pedal feel will be closest to stock with the 99-04 2-piston units as they are the closest of the two 11" SN95 setups to the stock 60mm calipers in terms of piston surface area, and a little bit softer with the 94-98 66mm calipers. Ideally, a 7/8" bore MC would probably be as "big" as you want to go here, but i'm not aware of one that will bolt on the 86 style Booster.

Don't compare your setup to setups with rear disk brakes. It's apples to oranges and you cannot go by why those setups use. Rear drum wheel cylinders have very small surface area compared to rear calipers, so that's why the stock MC is so small. The stock MC is roughly 0.83" in OD. Changing from that to a 1.00" OD bores is a HUGE jump. You're pedal stroke will be short, and leg effort will be very high. The larger OD you go, the more fluid you can move per linear inch of stroke, which means actual travel distance will go down.

When you decide to change your brake setup, then change the parts to match.

I wouldn't change the booster either. Your new calipers have a larger surface area compared to the old 60mm units you replaced. That fact alone, with the stock MC, means you will have reduced pedal effort and more hydraulic advantage. I would not put a cobra booster on. You're brakes will feel VERY over-assisted.

TL;DR: Stay with stock MC and booster for now.

THIS is exactly the perspective I was looking for and validates what I was thinking as well... thank you! Not sure which caliper I have, I will look tonight. Probably the single piston. But in either case, the stock BB and MC are probably best for now.

Thanks again! Id tip you if I could

 

[Mustang5L5]

No prob!

Now, just to toss a little extra tidbit out, What I would do in your shoes???

If you have the single piston 66mm units, I would look into getting a set of 99-04 2-piston units at some point in the future. The 2-piston units have slightly smaller surface area compared to the single piston 66mm unit.

Stock 60mm calipers: 5654mm^2 of surface area for both combined
94-98 66mm calipers: 6842mm^2
99-04 2-piston calipers: 6220mm^2

Running those calipers with the stock MC and booster will be slightly softer than stock, but you'll prob never really notice. Down the line, if you want to upgrade to reardisk brakes, you can run a SN95 GT/V6 rear setup, in which case a 1" Cobra MC and booster will be a perfect match.

 

[Buckhr]

No prob!

Now, just to toss a little extra tidbit out, What I would do in your shoes???

If you have the single piston 66mm units, I would look into getting a set of 99-04 2-piston units at some point in the future. The 2-piston units have slightly smaller surface area compared to the single piston 66mm unit.

Stock 60mm calipers: 5654mm^2 of surface area for both combined
94-98 66mm calipers: 6842mm^2
99-04 2-piston calipers: 6220mm^2

Running those calipers with the stock MC and booster will be slightly softer than stock, but you'll prob never really notice. Down the line, if you want to upgrade to reardisk brakes, you can run a SN95 GT/V6 rear setup, in which case a 1" Cobra MC and booster will be a perfect match.

Makes sense and I appreciate the surface area numbers. I didnt do the conversion, prior owner did and I didnt drive the car much before I started tearing it apart. As you can see from the pics, Im deep into engine and trans rebuild and I am prioritizing that work and just getting the car back together at this point. Since the current setup works, Im going to keep it for now and chalk up the ~$120 on a new BB + MC to a future project since it is wayyyy less than going rear disk/upgrading fronts at the moment.

 

[qtrracer]

I assume you've driven the car and experienced pedal stroke and feel. If so, was there something that you didn't like? If not, just use stock replacements. This is in line with what Mike is saying. Typically, the MC dictates pedal stroke - long/soft, the MC is too small for the system; short/hard, the MC is too big. The booster indicates how much pressure must be used to activate the brakes. Thus, you have to be careful mixing parts that are uncommon to the standard set-up.

On my 86, I went through several brake upgrade iterations over the years starting in '91. FWIW, I left the stock booster and MC in place, even when I went rear discs (the SSBC 4-lug conversion). MC only changed when I went to different sized front calipers, but the booster was stock 86 until this year when it went south. Currently running full Cobra front and rear with a 93 Cobra booster and MC. My next iteration is a Stop Tech 14" rotor and 4 piston caliper and same Cobra rear, and the current MC/booster.

 

[Buckhr]

I assume you've driven the car and experienced pedal stroke and feel. If so, was there something that you didn't like? If not, just use stock replacements. This is in line with what Mike is saying. Typically, the MC dictates pedal stroke - long/soft, the MC is too small for the system; short/hard, the MC is too big. The booster indicates how much pressure must be used to activate the brakes. Thus, you have to be careful mixing parts that are uncommon to the standard set-up.

On my 86, I went through several brake upgrade iterations over the years starting in '91. FWIW, I left the stock booster and MC in place, even when I went rear discs (the SSBC 4-lug conversion). MC only changed when I went to different sized front calipers, but the booster was stock 86 until this year when it went south. Currently running full Cobra front and rear with a 93 Cobra booster and MC. My next iteration is a Stop Tech 14" rotor and 4 piston caliper and same Cobra rear, and the current MC/booster.

This is all sound logic and matches my understanding as well. Your experience with the stock booster gives me a good sense of what might work for me for an extended period. I replaced the BB and MC with stock '86 components this week, here's the new one installed: