Fox Body Disc Brake Conversion Guide: SVE 5 Lug Kit

Get rid of those scrawny front brakes & rear drum brakes on your Fox Body Mustang with the SVE 5 Lug Disc Brake Conversion Kit. Follow along in this step-by-step installation article to see how you can transform your Fox Body with a weekend's worth of work!

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Fox Body Disc Brake Conversion Guide: SVE 5 Lug Kit - Fox Body Disc Brake Conversion Guide: SVE 5 Lug Kit

LMR team member Lee has been on a mission to build the ultimate daily driven road race Fox Body Mustang. Lee started with Eibach Pro-Kit lowering springs, UPR control arms, and Tokico shocks and struts in his initial build. Lee knew that to achieve “ultimate” with his Fox; he could not leave the 4-lug stock brakes on the car.

Lee had been drooling over the SVE Mustang Disc Brake Conversions for some time and decided to pull the trigger. He chose the 1987-92 28-splineSVE Mustang 5 Lug Disc Brake Conversion Kit. These brakes feature 13” Cobra Style front rotors, refurbished SN-95 spindles, 11.65” rear rotors, new axles, and many other parts. The installation will require one good weekend, a good set of tools, and preferably a lift for the Stang (not required, but you will need jack stands and jacks without it).

This swap does require basic mechanical knowledge. If you’ve never performed brake work before, but feel that you can with a little direction, couple this with one of our Haynes Service Manuals & you’ll be golden. We recommend picking up the 1979-93 version & the 1994-04 version, so you have all the proper torque specs for going back together. If you have any reservations at all, please consult with a professional shop to perform the installation.

Jump To: Front Disc Conversion | Rear Disc Conversion | Master Cylinder & Proportioning Valve

FOX BODY MUSTANG FRONT DISC BRAKE CONVERSION

The installation started with getting Lee’s car into the shop and on the lift. We pulled the wheels off the car and got right into tearing down his front 4-lug brakes. We removed the calipers by loosening the caliper bolts (pic below).

Fox Body Mustang Disc Brake Conversion Installation: SVE 5 Lug Kit - Mustang Disc Brake Conversion Fox Body

Next, we removed the grease cap on the front of the rotor. Once the grease cap was out of the way, we removed the cotter pin, nut retainer, nut, and rotor. With the caliper and rotor free, we had easy access to the spindles and suspension. We then loosened the tie rod nut and removed the steering tie rod. A large hammer or a “pickle fork” will be required.

The next step involves removing the front struts and spindles. To disconnect the strut from the spindle, we needed to remove the two retaining bolts & nuts.

NOTE: your front suspension is under load due to compression of the spring. Be sure to support the control arm with a jack or use spring compressors for your safety.

Then the spindle pulled away from the strut.

Once the spindle was removed, we changed out the ball joint with a 1994-2004 ball joint. Using a ball joint removal/installation tool, we removed the stock ball joint & installed the new SN95 ball joints.

With the spindles removed and the new ball joint in place, we reversed the previous steps and reinstalled a new set of refurbished SN-95 spindles.

Once the spindles were in place, we reinstalled the struts bolts and placed the new 13” Cobra rotors on the new hub assembly.

Next, we disconnected the stock caliper & brake hose. You remove the brake hoses by loosening the line nut at the body hard line (use line wrenches for this to prevent rounding off the nut) & then removing the retaining clip.

With these removed, you can now install the new stainless steel brake lines. The Fox Front Brake Line Adapter is mated to the SN95 braided stainless hoses to the Fox hard brake line on the passenger side.

Next, use the new hardware to install the SVE brake calipers and brake pads.

With the calipers installed, you can now reattach the outer tie rod ends (this is a good time to replace them). You’ll notice that you’ll have to adjust them out several turns to get them to engage the spindles properly. Because of this, you will need to have your front-end alignment fixed, as it will be off. The reason for the adjustment has to do with the wider track width provided by the 1996-04 front spindles.

You may also want to replace the sway bar end links at this time as well. Recheck all bolts and nuts that were installed & verify that they are torqued to specification.

NOTE: Some Mustangs may require front fender/fender well modifications depending on tire size and ride height, especially 1987-90, because of the smaller wheel opening. 1991-93 Mustang has a larger fender opening but may require modification. Modifications typically consist of trimming the fender & lower front spat for tire clearance and/or trimming the wheel well liner.

We rolled the fender on Lee’s car for some extra clearance. You will also need to have your front-end alignment checked because it will be off.

There you have it! The front SVE SN95 Cobra Style Front Brake Conversion can be used on your Fox Mustang in conjunction with our 5-lug Rear Drum Swap, or as part of the Complete 4-Wheel Disc Setup, we used on Lee’s car.

FOX BODY MUSTANG REAR DISC BRAKE CONVERSION

After wrapping up the front 5-lug conversion using the SVE 13" Cobra brakes and SN-95 Spindles, we moved straight into the rear brake setup. This installation section requires the most intensive labor – some modifications will be needed. During this installation section, you will be opening up the differential to remove the rear axles. This is a good opportunity to review some other preventive/predictive maintenance opportunities while you have the rear of the car in the air. If you have been thinking about adding rear-end gears (see this install here – Mustang Rear End Gear Installation), fixing that failing axle seal, replacing those old axle bearings or leaky differential cover gasket, now is the time to do it! Don’t forget the other suspension upgrades, such as rear control arms and shocks, if they are due for an upgrade.

Before you rip those ugly drum brakes off the rear end, let me cover the specialty tools you want to be sure you have before you start. One is a brake line flaring tool. The other is a good set of line wrenches. These can be picked up at your local tool supplier or other major tool distributors. You will also need a catch can for the old differential fluid. Other than these tools, you will find everything else in your typical 100+ piece “tool kit.” As with the front disc brake conversion section, follow each step below to walk through the installation process. Our sales/customer service team is also available to answer questions you may have about any of our products – 866-507-3786.

AXLE TEAR DOWN

With your Mustang up in the air & properly supported, remove your rear wheels & then the drums. Make sure the parking brake isn’t set, or you’ll never get those drums off! Place a suitable drain pan under the rear axle.

Next, remove 9 of the 10 bolts retaining the diff cover. Loosen the 10th one & leave it in place so that the cover doesn’t go flying off & oil splatters everywhere.

Use a gasket scraper or flat blade screwdriver to break the seal of the RTV between the cover and housing and let the gear oil drain. Remove the 10th bolt and the differential cover.

Using a 5/16" box end wrench and a lot of pressure, remove the differential cross-pin retaining bolt. Remove the cross pin, push in one axle shaft at a time and remove the retaining c-clips. A small telescoping pocket magnet helps with the c-clip removal.

Remove both axle shafts. Keep a rag handy as they will have oil on them. Now is a great time to replace your axle bearings & seals! (We had the rear sway bar removed in the following photos, it is not necessary for you to remove your swaybar to complete this conversion.)

REAR BRAKE TEAR DOWN

Once the axles are out, clean up a bit and move inside the car. Remove the console top panel and have someone underneath the car grab the equalizer bar on the front e-brake cable while you pull the cable toward the car's rear about 2 inches or until the holes in the handle & spring wheel are aligned.

Insert a pin (an Allen wrench works great) in the holes to keep the spring tension assembly in the released position.

Remove the parking brake cable ends from the equalizer bar.

Remove the bolts that retain the cable to the chassis of the car.

Using a 9/16" box end wrench, slide it over the end of the cable, and release the retaining clip. Pull the cable free from the chassis.

NOTE: Mustangs from 87-92 will have the retaining clip located near the frame rail. If you’re working on any 1993 Mustang, it clips to a bracket just behind the front cable & equalizer bar.

Now, take a look at the four bolts/nuts that hold on the drum brake backing plate. Remove the bolts & nuts and set them aside as you will reuse them later.

Clean the axle flange to remove any rust or scale that may be present.

BRAKE BRACKETS & AXLE INSTALLATION

Using the 4 nuts & bolts removed earlier, attach the Caliper Adapter Axle Flanges.

Install the included Wheel Studs in your new axles and slide your axles back in place, securing them with their c-clips.

Re-install the differential cross pin and retain it with the cross pin bolt. Do not overtighten! While you can use RTV to re-seal your diff cover, we like using the LubeLocker gasket. Much cleaner & no dry time!

Re-install your differential cover and refill the axle housing with the included Royal Purple Gear Oil & FRPP Friction Modifier. A suction gun (which can be found at your local auto parts store) makes the refill process much easier.

Rear Axle Lines

When installing a rear disc conversion with the SN95 rear brakes on your Fox Mustang, for a plug-and-play installation on the rear axle lines, use the rear axle lines conversion lines for a quick and easy installation. This will allow the installation of the caliper brake hoses without flaring the old hardlines. If you are flaring your old lines, follow the steps below.

Removing the lower shock bolt will allow for extra working room while flaring the line.

Install your new braided rear brake hoses.

NOTE: Since this installation, we have changed suppliers on our brake hoses & the bracket is now part of the hose, not a separate piece as illustrated below.

Your axle housing may not have the holes needed to attach the rear hose. If not, take a drill & ¼” drill bit and make two holes per side. One is for the locating tab, and the other is for the retaining bolt. Retain the hoses using the supplied retaining bolts.

Mark your existing axle-mounted brake hardline at the length needed to comfortably connect it to the hose. Err on the side of long if anything. Cut the line and install the included brake line nuts.

Now on to using the flare tool! If you’ve never used one before, there are several good youtube videos on how to make a successful double flare. Clamp the line in the flaring block and insert the correct collet for the line size. Use the flare tool to make the first part of the double flare. Remove the collet and make the second part of the flare using the flaring tool. Remove the flaring block.

Attach the hard line to the braided hose.

Install the Center Axle Braided Brake Hose.

REAR CALIPER INSTALLATION

Install the rear rotors and slide on the new calipers.

Attach the calipers to the axle flange brackets using the included hardware.

Attach the brake hose to the caliper using the new copper washers and banjo bolts included in the package with the rear brake hoses.

Re-install the lower shock bolts.

E-BRAKE CABLE INSTALLATION

Slide your new parking brake cables through the chassis and engage the retaining clips.

Install the ends into the equalizer bar.

Remove the retaining brackets from the old cables and install them on the new cables. Use the original bolts to attach them to the chassis.

Remove the front bolt from the rear sway bar.

Install the included parking brake cable guides over the cable and retain the guide to the rear control arm with the sway bar bolt.

Install the rear cable ends in the parking brake levers on the calipers.

Go back inside the car & remove the pin (or allen wrench) from the e-brake handle.

Re-install the console top panel.

Congratulations! – You have just completed the rear portion of a Fox Mustang 5 lug, 4-wheel disc swap! We have also included alternative parking brake modification steps for 87-93 Fox Body Mustangs that are converting to a rear disc brake setup. Check out our modification video below!

FOX BODY MUSTANG MASTER CYLINDER & PROPORTIONING VALVE INSTALLATION

When doing a 5-lug, 4-wheel disc swap on a Fox Mustang, the number one question we field is “What do I have to do with the master cylinder & proportioning valve?”. Unfortunately, there is no one size fits all answer, as it depends on your brake setup. We tried a few different options for our SVE Brake Conversion Kit and landed on the 1993 Cobra Master Cylinder as it provided a pedal feel that appealed to most drivers. Follow along as we walk you through the installation on Lee’s Fox Body Coupe!

MASTER CYLINDER REMOVAL

Start by removing the stock master cylinder. You’ll want to pack a bunch of paper towels and/or rags in the area underneath, as brake fluid will be going everywhere.

Unplug the low fluid sensor on the master cylinder reservoir.

Remove the two nuts that retain the master cylinder to the booster.

Then, using a good set of flare wrenches (preferably name brand, like Craftsman), loosen the two-line nuts that attach to the top of the proportioning valve/distribution block and also the one line nut that goes into the bottom of the master cylinder.

Carefully remove the master cylinder from the car. Quickly clean up any brake fluid with soap and water, so it doesn’t damage your paint.

PROPORTIONING VALVE MODIFICATION

Now, it’s time to “gut” the stock proportioning valve/distribution block. Change out paper towels! It's going to get messy.

Take a ¾” wrench & remove the large hex head plug on the front of the proportioning valve. Be careful as there is a spring behind the plug that will cause the plug to shoot out if you don’t watch it.

Remove the spring and shuttle valve from the hole and discard.

Remove the larger o-ring from the stock plug & transfer it to the solid proportioning valve plug included in the kit (The plug is an LMR.com exclusive!).

Install the new Solid Plug in the proportioning valve. What you just did was defeat the stock mechanism for rear brake pressure bias. This is why you have to add in an adjustable proportioning valve.

On the passenger side of the firewall, you’ll find a union in the hard brake line that runs to the rear of the car. Remove this union and install the included adjustable proportioning valve. Screw the knob on the valve all the way in for bleeding purposes.

MASTER CYLINDER INSTALLATION

Remove your new master cylinder from the box & bench bleed it.

With the new 93 Cobra Master Cylinder bled, transfer the stock front hard line from the stock master cylinder to the new one. Install the 3 port to 2 port conversion for the rear port, as shown below. The hard-line on the car that runs to the left front will screw into the bottom of the T-fitting of the conversion kit.

Install the new master cylinder & tighten all connections. The stock retaining nuts can be reused.

Many people will tell you that a booster replacement is required. It isn’t. Pedal effort is very relative & dependent on the driver of the car. If you feel the pedal effort required to stop is too great, then adding a 1993 Cobra Brake Booster may be the best case of action As stated earlier, we chose the 1993 Cobra master cylinder as the pedal effort required to stop the car was acceptable to the most people who drove the car.

BLEED YOUR BRAKES

Add fluid & bleed your brakes!

Start with the passenger rear caliper, then move to the diver rear caliper, then the passenger front, and finally the driver front. Here is an excellent source for info on properly bleeding your Mustang brakes the right way with quality DOT 3 brake fluid, like Motorcraft PM1C, would be an excellent choice for your Mustang.
Periodically check the fluid level in the master cylinder while bleeding and top off as needed. You should also check for leaks and tighten any fittings if a leak is present.
Now, go back to the adjustable proportioning valve. Check out our How To Set Adjustable Proportioning Valve article for a complete guide on the adjustment process.

There are quite a few steps to this process but keep in mind that this project will completely overhaul your braking system! You will now be able to trust your brakes and have confidence, and even more, fun, diving your Fox Body Mustang!