Disk Brakes On My 86

[Dane Brahler]

Hey all,
Car has cobra 13" front spindles and I have all the components for the rear disks. (All 5 lug already)
So I'm stuck at the MC and proportioning valve.
Car has stock pieces installed currently.
Question is: can I use an 88 MC on the stock booster?
Can I block off bottom hole on the 88 MC and connect to the stock prop valve and simply gut it and use the new front block bolt from lmr?

 

[Dane Brahler]

Another possibility?:
Use stock MC and stock prop valve and gut the valve and cap off with block bolt?

 

[Mustang5L5]

You need a MC specifically for 4 wheel disk brakes. The 1988 MC is still spec for rear drums, so if you install it your pedal will be extremely soft, and the travel long. You'll be rather disappointed in your braking performance

Assuming you used rear SN95 disks, the MC you should use depends on which Cobra calipers you installed.

94-98 with 38mm pistons = 94-95 Cobra 15/16" bore MC

99-04 Cobra/bullitt/Mach1 with 40mm pistons = 1993 Cobra 1" bore MC.


Best way to tell the difference between the Cobra calipers is to look at the underside of the piston bores. The 94-98 38mm calipers have ribbing on the bores, while the 99-04 versions are smooth.

38mm on left, 40mm on right

Once you've identified which front calipers you need, you just need the MC and adapter kit. I've usually sourced my MC's from parts stores as they tend to be cheaper.

MMBAK-9 is the adapter kit for 94-95 Cobra 15/16" MC
http://www.maximummotorsports.com/M...master-cylinder-in-1980-86-Mustang-P1273.aspx

MMBAK-17 is the adapter for the 1993 Cobra 1" bore MC
http://www.maximummotorsports.com/M...master-cylinder-in-1980-86-Mustang-P1273.aspx

Another option if you determine the 1" MC is what you need, is a 1985 Lincoln Town car MC. It matches the style of MC you currently have, and may be much cheaper. Downside is you need one adapter fitting where I don't have a source for. Refer to this chart

http://1985mustanggt.com/Reference/2009-09-19_Mustang_MC_Info.pdf




As for the prop valve, gut the stocker by removing the front nut and install the prop valve plug part. Then, install an adjustable unit on the firewall at the pass side rear firewall union.

 

[Dane Brahler]

You need a MC specifically for 4 wheel disk brakes. The 1988 MC is still spec for rear drums, so if you install it your pedal will be extremely soft, and the travel long. You'll be rather disappointed in your braking performance

Assuming you used rear SN95 disks, the MC you should use depends on which Cobra calipers you installed.

94-98 with 38mm pistons = 94-95 Cobra 15/16" bore MC

99-04 Cobra/bullitt/Mach1 with 40mm pistons = 1993 Cobra 1" bore MC.


Best way to tell the difference between the Cobra calipers is to look at the underside of the piston bores. The 94-98 38mm calipers have ribbing on the bores, while the 99-04 versions are smooth.

38mm on left, 40mm on right

Once you've identified which front calipers you need, you just need the MC and adapter kit. I've usually sourced my MC's from parts stores as they tend to be cheaper.

MMBAK-9 is the adapter kit for 94-95 Cobra 15/16" MC
http://www.maximummotorsports.com/M...master-cylinder-in-1980-86-Mustang-P1273.aspx

MMBAK-17 is the adapter for the 1993 Cobra 1" bore MC
http://www.maximummotorsports.com/M...master-cylinder-in-1980-86-Mustang-P1273.aspx

Another option if you determine the 1" MC is what you need, is a 1985 Lincoln Town car MC. It matches the style of MC you currently have, and may be much cheaper. Downside is you need one adapter fitting where I don't have a source for. Refer to this chart

http://1985mustanggt.com/Reference/2009-09-19_Mustang_MC_Info.pdf

Thanks for the reply!! What about the booster?


As for the prop valve, gut the stocker by removing the front nut and install the prop valve plug part. Then, install an adjustable unit on the firewall at the pass side rear firewall union.

 

[Dane Brahler]

Screwed up my response. Can I get away with using the stock booster?

 

[Dane Brahler]

Screwed up my response. Can I get away with using the stock booster?

 

[Mustang5L5]

You can try it, and see how it feels. Ideally, you should swap in the larger 1993 cobra, or 94-95 SN95 booster for max results, but some people like the effort when leaving the stock booster in.

So my advice is give it a shot, but if you find your leg effort is much to high for your liking, swap the booster in.

 

[Mstng93SSP]

My opinion is this. You can not run the stock booster with that setup. Pedal will be hard and braking will be almost worse than a stock drum setup. I have done 5 lug, 4 wheel discs on 7 cars and counting. I bought a car with a disc conversion already done to it but had the stock booster. On the freeway during a panic stop I had both feet into the brake pedal with all my 220lbs and came inches from rear ending a truck. Don't run the stock booster. Put a 93 cobra booster. It's not hard to do.

 

[General karthief]

On the subject of boosters, could a hydra boost setup work?

 

[Mustang5L5]

It gets assist off the power steering.

A bit more involved of a swap.

 

[General karthief]

I know, was wondering if it would be more efficient with the bigger brakes.

 

[CarMichael Angelo]

Hmmm,...not only is my booster stock w/ SN brakes all around,...It's the factory fairmont unit rated for the stock weanie disc/drum setup that came on the car in 78.

Firstly,...There is absolutely no detriment to the braking w/ this setup,...I have noticed nothing that I would remotely describe as marginal in the braking performance, and I have already stood on these brakes fairly hard.
Secondly, When compared to the strut tower butchery that has to take place when a Cobra booster is put in place,...mine leaves miles of room. Finally,... If you're gonna gut the stock prop valve and the use a adjustable unit located elsewhere to bias the rear brakes,..you may as well consider killing two birds w/ one stone.

 

[Noobz347]

checkout @RacEoHolic330 's build too. He's running hydro-boost IRC

 

[Mustang5L5]

If I ever redo my brakes lines, that's the unit I'm going with

 

[Dane Brahler]

the town car mc: you cant beat the price but hunting down the fittings has got to be a nightmare, also, i checked and i have the smooth bore 99-04 front calipers. the 93 cobra cylinder looks like my guy with the line adapters from MM. As far as the booster goes, I'll try what i have for now. Updates soon when i get the parts!

 

[Mustang5L5]

I know, was wondering if it would be more efficient with the bigger brakes.

It's more consistent due to the pedal effort not changing due to different vacuum levels in the engine. Really, it's only worth it if you don't have the space for a vacuum booster such as installing a mod motor.

Price out the parts and it's not cheap

 

[Dane Brahler]

so i was just looking at the prop valve eliminator kit... Ive got two lines going in the top of my stock prop valve, 2 lines out the bottom and a single one out the rear.. I understand the top and bottom going together but where does the single one connect to if you use this kit?

 

[Noobz347]

You should look through 5L5's brake thread:

http://www.stangnet.com/mustang-for...5-lug-brake-conversion-upgrade-thread.801400/

 

[Mustang5L5]

I don't think I cover it there. The delete kit wasn't out when I wrote all that out.

Neither was that awesome Wilwood piece above

 

[Noobz347]

The "Almost ultimate....