Kinda off topic as far as this forum goes but I'm kinda stumped here.

1988 fox with turbo 5.3

Bought the car and it had 4 lug disk brakes already on the car but they do not work.

Its like they bolted everything together in the rear end and just walked away.

What do I need to buy to make the brakes work? I thought I needed the 93 cobra master but I keep finding different answers on different forums as far as what I need.

Does anyone know the answer to my problem? Would also like to find what E brake cables needed as well. Car is 4 lug currently and I have no idea what the brakes came off but the lines calipers and everything is already hooked up.

I would greatly appreciate the advise thanks guys

 

yes on master but also proportioning valve. Check Maximum motorsports website, they had some good info.

 

Will an adjustable porportiong valve take care of the problem or do I need a specific one?
Maximum motors ports talks about an adjustable one as an upgrade but I'm still unclear

 

Its been awhile, but if i remember you gut or do something to the proportioning valve. they have the fittings like 20.00 range. They have great phone tech. Then you can use a adjustable valve.

 

Need more info. I went to look at your build thread but the images are blocked in my office.

What was the car originally a 4cyl or a 5.0? The 4cyl has a different brake booster than a v8 car and should be swapped out if going to v8 brakes. Either a 93 Cobra booster or swap in a 94/95 GT booster, which will not be a simple bolt in.

Need to define "not work". Do the brakes lock up instantly? Are they squishy? Can they be bled adequately but have very high pedal effort and don't slow the car down? Etc. There are so many variations of disc brakes on a Fox platform that nobody will be able to give advice without understanding the problem or understanding what is already there.

For the master cylinder, it really depends on which calipers you have front/rear. The swept area of the master needs to be a certain ratio of swept areas of the caliper pistons. Even if you don't know what the brakes are from, measuring the diameters of the caliper pistons front /rear will get you started. Staying with the OEM ratios typically works well. IE, either 38mm (94-98) or 40mm (99-04) Cobra calipers in the front and standard GT/Cobra SN95 Vargas calipers in the rear work well with SN95 Cobra MCs of 15/16" diameter or 93 Cobra master cylinder of 1" diameter. The SN95 rear Vargas calipers are the same over the various Mustang sub models with OEM discs, the mounting difference is from the caliper bracket and brake pad thicknesses which positions the calipers over the larger diameter and thicker Cobra disc. Unless you have the old SVO rear brakes or old Thunderbird / Lincoln LSC rear discs in which case you won't have the Vargas calipers in the rear.

If you have SN95 brakes then you will either need to swap out your OEM proportioning valve internals to OEM SN95 parts or remove the OEM proportioning valve function and install an adjustable valve in the rear. If you have the old Tbird/LSC brakes you should go adjustable valve or because finding an old Fox3 disc brake proportioning valve is probably not worth the effort.

 

Very well said and great info. Nice when somebody takes the time to answer with so much info.

 

i had all sn95 except for the master and booster. i gutted the stock proportioning valve , the car stopped great and didn't lock the rear prematurely

 

As usdmholden said, you haven't given enough information for folks to be able to answer your questions.

If the rear disks are 4-lug then they're not SN95 or SVO/LSC. So, they're either the Tbird Turbo Coupe rears (which were the same as the '93 Cobra rears), or the very similar kit that SSBC has sold for years that was basically the same thing. AFAIK the only real difference between the Tbird/Cobra brakes and the SSBC kit is the axle length - Tbird/Cobra rears are 0.75" wider (each side), while the SSBC kit is designed for stock axles - so that shouldn't matter for troubleshooting why the brakes don't work right. (More info here.)

Amen!

Just to clarify, the LSC rears were the same as the SVO, not the Tbird. LSC and SVO were both 5-lug, with a rotor about an inch bigger than the Tbird rears.

 

Seems to be some solid FOx knowledge in here so I'll ask this, its related; Whats the hardest biting pad for the 4 bolt stock front disks?

 

For what, street or track? With OEM 4 lug discs I'm going to assume it's not an open track car.

For street pads the Hawk HPS work well and are relatively low dust. There is a comparison of Hawk offerings in the Max Motorsports website. They can be bought cheaper with free shipping elsewhere.

http://www.maximummotorsports.com/Ha...ront-P612.aspx

I also ran EBC Green Stuff pads on other cars but not Mustangs and was happy with them on the street as well.

 

For what use? Cold or hot bite? Do you care about dust or noise or rotor wear?

My personal experience with the HPS pads was very underwhelming; I removed them from my CTS-V after only a few months, something I've never done with any other pads I've bought over the years. The Hawk HP+ will offer significantly more bite than the HPS, at the cost of lots more dust and some noise. Hawk also has two newer street pad compounds that were introduced this year - High Performance Street 5.0 and High Performance Street/Race. I have no personal experience with either, but I have seen one review from someone who has tried the HPS and the HPS 5.0 and he said the 5.0 was a big improvement.

As for what I run, I replaced the HPSs on my CTS-V with ACDelco Professional Durastop semi-metallic pads. They were on closeout on rockauto.com for only about $25 (as compared to $155 for the HPS), so I figured at that price it couldn't hurt to try them out. Turns out I've been thrilled by their performance. They definitely generate more dust than the HPSs, but they're not horrible in that regards, and the braking power, both cold and hot, is leagues better than the HPSs. I'll continue to spend big bucks on brake pads for track duty, but when it comes to street use I'll be sticking with these dirt cheap ACDelcos for the foreseeable future. Looks like the part number for the stock Mustang brakes is 17D431M, and they're only ~$10 on rockauto.com - again, for that price, it can't hurt to try them out.

 

Its a cruise/drag car but i'll need to haul it down from 150 or so safely and the option of 15" front wheel is important so Im trying to stick with stock size front rotors and just do a 5 bolt rotor and go. Ive used Green stuff pads in the past and thought they worked great but the dust.... blah. I have Hawks on a car now that work well.

But my last notch was damn scary braking hard on the stock brakes ( Ford pads ) so maybe even a caliper swap is in order

Damn fox bodies... so many variations and none of them great in terms of braking solutions. SN95 swap works decent but the 15" wheel issue.... hmmm

 

The SN95 V6/GT brakes fit with 15" wheels (the V6s came with 15s). I don't know about the various drag wheels, but there were factory 15x6.5" steelies and 15x7" alloys. The Fox GT and SN95 V6/GT both have basically the same size rotor (11" x 26mm), but with the SN95 you get a significantly better 2-piston caliper, more pad swept area, better spindle strength and geometry, separate sealed hub bearings (no more repacking bearings every time you pull a rotor), and way more options for upgrades if you ever decide to go bigger.

 

^ That sounds ideal! So what years am I looking for? To be clear I need the spindle, bracket, calipers, rotors, pads and? Thanks for the advice, appreciate it

 

The 1994/1995 spindles combined with 1999-2004 V6 brake calipers and rotors and 1994-2004 ball joints will get you most of the way there. Then you need to adapt the brake lines which can easily be done with either OEM 1999-2004 hydraulic hoses and adapter fittings, or with brained stainless adapter hoses from MM. If you use the 94/95 spindles with the 99+ calipers you will have to grind a very small amount off the spindle to make it fit. Not hard, last time I did it it took about 5 minutes with an angle grinder, and I was being ****.

You could also run 1996-2004 spindles but you will have some bumpsteer. Granted, if you are running skinnies on a drag car, bumpsteer really won't be much of an issue to worry about.

For a drag car standard semi metallic OEM replacement pads will be fine. Due to the skinnies the bulk of the braking will actually come from the rear.

You will need to swap out your master cylinder to an SN95 or 93 Cobra unit and do something with the proportioning valve as mentioned above. In your case prob a 93 Cobra will be better otherwise you will end up with adapter fittings between the fox brake lines and the SN95 master cylinder. Fox is SAE inverted flare, SN95 is metric bubble.

 

Two posts and Im sorted. Thanks man. Off to the yards I go