Cobra master cylinder question for mdjay and others.

[Jimmys66]

Mdjay, I know you are not running the cobra brakes, but I'm looking to use the JMC MC and have heard you have extreme pedal effort. What size bore MC did you buy?

I talked to JMC today and they will build me one with any bore I want no extra charge. I know the use of an 84 svo MC with a 1-1/8" bore works and wanted to compare to the bore size in your MC.

For the question that is coming next.....Yes I could use the svo MC but it is honestly the uglyest thing I've ever seen and wanted something polishable (read Bling Bling ). Any suggestions other than a JMC MC?

 

[66Runt]

Cobra brakes designed for a power booster application

There in lies the issue with using non-power master cylinders. You could use a 15/16" front and rear with a good adjustable proportioning valve, but I think you will find it is still very firm. 7/8" would be great as far as leverage goes, problem is the stroke is too long with a 7/8" bore.

I picked up the power booster/4wheel disc master from NPD (because I needed one to fit a standard transmission Cobra 4WD). It uses a 1" bore front and rear, and has a good volume differential to match the front and rear as well. That allows more pressure and still keeps a good balance. This is the same system that Jay has, only his is for front disc, rear drum.
with a good idle vacuum of 18", I"m very satisfied. A little stiffer than an '01 Vette, but I can stop within a car lengths difference, and the Vette has much bigger tires. Of course it weighs a lot more too. Come to think of it, the Vette is kind of a pig in comparison to my svelte little pony.

Anyways, I think you may want to consider a power booster of some sort. The piston area in the PBR calipers just isn't big enough to support a non-power application for street use.

Good luck whatever you decide,

 

[Jimmys66]

I've always wanted to keep this car completely manual. If there is no other choice I wouldn't have a problem with power brakes.

That being said, the cam in this motor is almost positively going to keep it a manual set up. Maybe I want my cake so to speek, but I want something that proforms well and looks good.

I've read that the svo mc seems to be tried and true and I may have to go that way, but I wouldn't mind spending $100 more for something that looks nice to. The JMC is now $377 which seems excesive for a mc but in the long run I've pissed away alot more than that in dumber things. I would like to make sure it is going to be $377 well spent.

 

[gsxrken]

Some real good reading here (particularly the Excel spreadsheet link):
http://www.corner-carvers.com/forums/showthread.php?t=21615&highlight=pedal+ratio

Hope it helps you nail your setup the first time around.

 

[4MuscleMachines]

I used the JMC dual unit with 1" front and 7/8" rear bores and the effort is still too uncomfortable for me and I am 6'2" and 240 lbs. I even have the six piston Wilwood front brakes which should have made the effort easier since the pads are smaller, but I believe it had the opposite effect.

 

[Pbum5]

I've read that the svo mc seems to be tried and true and I may have to go that way, but I wouldn't mind spending $100 more for something that looks nice to. The JMC is now $377 which seems excesive for a mc but in the long run I've pissed away alot more than that in dumber things. I would like to make sure it is going to be $377 well spent.

Try $300+ more.
I paid under $30 for a reman 84 SVO MC and like $15 for a core charge.
It's all aluminimum and looks better than a stock Mustang MC.

I have 4-wheel discs and have no problem with brake effort. Don't have cobra brakes though.

Not as cool looking as a JMC unit but that might be overkill.

 

[mdjay]

I'm not completely sure but I think they're 1" bores... The car does stop really well but you really have to push it hard to make it happen. I'm stuck between bling and function myself as well. I haven't addressed this issue at this point. While I'm not in a hurry, I'm considering a hydro boost set-up, or using one of these new ssbc masters with a chrome booster. View attachment 452713

It would require modification to the push rod and bracketing to clear my hydro clutch. Then I would need the vacuum booster as I don't have enough vacuum to run it effectively.

 

[66forfun]

my pbr's that came with the manual baer front "track" kit works flawlessly, I still have drums out back. I do have the 13" rotors and im sure that helps....I love my brakes. . Unfortunately I dont know about bore sizes but it looks just like a manual MC out of a ranger.

 

[Jimmys66]

I read the corner carvers post last night and it got me thinking. They were talking about how the bore size on the baer brakes MC shouldn't work, but for some reason it works well on a manual system. It dawns on me that baer sells a manual pbr brake kit.

I call the tech line at bear and fessed up as to what I was doing. Thinking I would buy a baer MC to get the system to work and that it wasn't really all that bad looking. The tech guy tells me that the mc on the kit is.........

out of a 1994 to 2004 mustang cobra. How obvious this should have been to me. He told me the 15/16" production piece worked so well that they didn't bother to make one themselves.

This would also answer why they look like one out of a ranger and I think I heard someone say they used a windstar mc and it worked well also.

 

[66forfun]

Good people over @ baer, Great product...I guess "manual" was the key. I am going with a big lumpy cam and dont want vac problems, plus 66's are tight with the right size booster and headers.

 

[ultrastang]

I read the corner carvers post last night and it got me thinking. They were talking about how the bore size on the baer brakes MC shouldn't work, but for some reason it works well on a manual system. It dawns on me that baer sells a manual pbr brake kit.

I call the tech line at bear and fessed up as to what I was doing. Thinking I would buy a baer MC to get the system to work and that it wasn't really all that bad looking. The tech guy tells me that the mc on the kit is.........

out of a 1994 to 2004 mustang cobra. How obvious this should have been to me. He told me the 15/16" production piece worked so well that they didn't bother to make one themselves.

This would also answer why they look like one out of a ranger and I think I heard someone say they used a windstar mc and it worked well also.

The tech guy must have meant the '94-'95 Cobra MCs. Those two year model Cobras used vacuum boosters. Starting in '96 though, they went to hydroboost on the Cobras, which has a MC with nearly a vertical mounting flange pattern on the MC, instead of the earlier '94/'95 Cobra MC which has a horizontal mounting flange on the MC.

 

[Jimmys66]

I'm glad you brought this up. I hate to start giving out wrong info. Alot of people are doing this swap and the MC aren't really that cheap.

The parts guy ordered me a 94, showed me a pic and confermed the bore size for me. I should have it tomarrow and hopefully will have it mounted. I won't have the kit done until next weekend and I'll pass on how well or not it works.