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How to Install Wilwood’s Four-Wheel Disc Brakes
Wilwood’s conversion kits give vintage Mustangs modern braking power
Cars have gotten quicker in every aspect over the years, but there’s one statistic in particular that means more than the rest—braking distance. What was considered good in the ’60s and ’70s would be bottom of the barrel today. Sadly, even the top-dog Shelbys and Boss 302s can’t touch the numbers many modern four-door sedans can pull. It’s sad, but true; the four-wheel drums most Mustangs were shod with can get you in serious trouble in an emergency braking situation surrounded by newer cars.
For a dose of reality, we took our stone-stock, four-wheel manual drum–equipped ’68 Mustang shod with 17x8 and 17x9.5 Vintage Wheel Works V50 wheels and Nitto NT05 tires out for a few 60-to-0 deceleration tests. Our very best result was 210.4 feet. Read that number again slower. That’s over two-thirds of a football field. Most modern 1-ton pickups can stop faster than that, and every single car built in the last 20-plus years can as well. If the tires on your vintage car are harder, and/or your drums haven’t been checked lately, your stopping distance could be even worse.
So how much brake do you need? For bare minimum safety in today’s traffic, all of which can stop much faster than any ’70s or older car, we’d recommend at least original-style discs up front to at least get in the game. If you like to drive fast or through the curves then it’s time to look at better calipers and pads and get some discs on the rear too. Really enjoy pushing your car or getting it out on autocross tracks or road courses? Now it’s time for some 13- or 14-inch rotors and big multi-piston calipers. It really all comes down to what you want to do with the car and how repeatable you need the performance to be.
For this ’68 coupe, autocross and canyon running are in the cards, so a more aggressive than average brake system is needed to complement the tires and planned suspension work. For decades, getting super aggressive packages installed would have involved custom machining to adapt stock late-model or full race car parts. Those days are long gone and now companies like Wilwood have stepped up and created full, proper, serious-performance disc conversions with just a few part numbers. There’s more than bolting on a set of calipers and rotors to creating a truly effective braking system; it takes a complete rethinking of the whole system to create something that works like it was built that way originally. Wilwood has taken the tough part out, though, with their new Mustang brake swap page at www.wilwood.com/mustang. After choosing your year and spindle type, the page will present all front brake package options available for your car. For the rear, Wilwood can tailor a complementary kit for your particular parts. It’s just that easy!
Wilwood was kind enough to handle the front brake install on our coupe, but for the rear we needed Mustang-specific expertise, so we put our trust in Mustangs Etc. in Van Nuys, California. These guys not only have one of the biggest and nicest Mustang-only shops we’ve ever been to, they also have an extremely knowledgeable staff and just about every single chassis and mechanical restoration part you could possibly need in stock; plus an unprecedented stash of original stuff. They may have a strong restoration clientele, but they’re completely competent with high-performance upgrades like this. You can trust the work here to be right.
01. Included in the SL6 Mustang front brake conversion kit is Wilwood’s forged narrow Superlite 6R (FNSL6R) caliper. This is their newest version for the Superlite caliper series that adds versatile radial mounting to provide two planes of adjustment for accurate alignment over the disc. The kit is actually quite simple and the swap can easily be done in a day at home.
02. Not only will your wheel choice determine the diameter of rotor usable on your swap, it may also determine the caliper that will be required for adequate clearance. Wilwood always recommends using the proper sizing chart (this one is for our 13-inch, six-piston kit) to check your wheels before ordering.
03. To give them a fair shake for testing, we made sure our drums were in good shape prior to testing. The shoes had plenty of good material and were in proper adjustment, and the wheel cylinders were new. Removing the drum is as simple as four bolts on the spindle. The hydraulic hose was left connected for now to prevent a mess.
04. The drums had never been removed from the spindle, but we thankfully had little rust to deal with. A wire brush was used to clean up the scale and make sure the bearing surface was free of corrosion.
05. The caliper mounting bracket is designed so that it can be used on either Ford disc or drum brake spindles, so both bolt patterns are included. Our Mustang’s spindles are drum, so the four appropriate holes were lined up and the button-head Allen bolts were installed.
06. Multiple .015 shims are provided with the kit to allow for differing tolerances in the spindle and make it possible to have ideal alignment with the caliper on the rotor. We have to get it all assembled to know for sure, though. Once the number of shims is determined, red thread locker is recommended.
07. This is the radial mount bracket that will hold the six-piston caliper in place. Using this mounting solution allows for easy adaption of the caliper to multiple spindle designs.
08. To mount the rotor, Wilwood conversion kits for vintage spindles use an aluminum hub. The bearings are included, but will need to be packed with high-temperature disc brake bearing grease and installed. The hub then installs directly on the spindle and is lightly secured using a spindle washer and the OEM spindle nut. The nut should be tightened per OEM specifications with a new cotter pin.
09. Wilwood’s lightweight two-piece rotors require assembling the outer discs to the rotor hat with an alternating sequence on the bolts. Red Loctite 271 is applied to the threads, and they are torqued to 155 in-lbs. For added safety, especially in competition use, the bolts can be safety-wired using standard 0.032-inch-diameter stainless steel safety wire.
10. Wilwood’s cool e-coat not only keeps the rotor from rusting before use, it keeps all the non-braking surfaces corrosion-free, even after use! The hat/rotor assembly slides in only one way since the small countersunk holes in the hat must line up with the small threaded holes in the hub. Three flathead screws install through the small holes in the hat, and get torqued to 85 in-lbs.
11. Most Mustangs will use all three alignment shims to get the correct centering of the caliper, and our ’68 was no exception. They may look the same, but there are distinct right- and left-hand calipers that must be mounted in a specific direction. The calipers must be mounted so the largest of the three pistons per side are at the rotor exit end of the caliper, in relation to the direction of rotor rotation.
12. They are technically an option, but we say always replace your flexible brake lines with new ones when upgrading a vintage car. The stock rubber ones are guaranteed to be dry and prone to cracking. These braided ones from Wilwood will not only last for many years, but the covering keeps them safe from abrasion.
13. Wilwood’s popular aluminum, tandem master cylinders will be used for this install. These work great on manual or power brakes, and will fit just about any vintage car, though we have a Mustang-specific pedal rod kit. Bench bleeding is a necessity, and each master cylinder incudes a pre-plumbed kit. We’ll be using Wilwood’s EXP 600 Plus high-temp racing brake fluid.
14. Our master cylinder kit included a new adjustable proportioning valve to replace to original distribution block. Controlling the front-to-rear pressure bias will be extra critical since will still have the factory drums on the rear for now. The brake pressure sensor on the end will be removed and plugged since our ’68 Mustang has one on the pedal.
15. This mounting bracket makes life simple for getting the proportioning valve in place. The plumbing, however, will require a bit of reworking. Using a flaring tool, Wilwood was able to reuse most of the original lines since they were in good shape. Ideally, this would be a good time to replace all of them.
16. Fast forward to Mustangs Etc.; this is the original 8-inch leaf springs and rearend our ’68 coupe left the factory with; we added the drop blocks. Wilwood offers kits compatible with this rearend, but we are taking the opportunity to swap rearends since we have lots of plans for the driveline that the high mileage unit won’t like.
17. Typically the parking brake cables would just be disconnected from the rearend before removal, but we’re removing these completely since the Wilwood disc kit comes with internal drums and new cables.
18. Thankfully our stock driveshaft will fit the new rearend without issue, though we will need to upgrade to a 1350-style U-joint and 9-inch U-bolts to fit the Currie yoke while we have it out. The smiling tech is our good buddy Gil Roiz, a master Mustang mechanic.
19. Rather than wiggle the rearend out over the springs, we decided to just drop the leafs. Plus, these original bushings are looking kind of shot and this is the ideal time to address the issue.
20. A transmission jack makes this job so much easier! A ratchet strap was used to secure the rearend as Gil and fellow master Mustang technician, Steve Miko, balanced it while it lowered. If you’re working from jackstands, a good hydraulic floor jack will work just as well.
21. With the Currie 9-inch replacing the 8-inch on the trans jack, Gil lifted it into place. Though it might look like bare steel still, we actually gave it a good coating of VHT stainless steel paint. We highly recommend this stuff for its durability. We didn’t just paint the original leaf springs, though, Mustangs Etc. had five-leaf reverse-eye springs with polyurethane shackle bushings in stock, and since the stockers were already removed we just couldn’t resist the chance to get better handling and lose the drop blocks.
22. After sliding the axles out, the Wilwood parking brake assembly slides on and butts up to the axle flange. It will be secured by the bearing retainer plate and stock bolts with red Loctite 271 torqued to stock spec.
23. Some axles, such as our Currie units, will require this rotor register adapter. It slips over the center of the axle flange to help center the rotor hat.
24. Just like the front, the two-piece rear rotors require assembling. Red Loctite 271 is applied to the threads, and they are torqued to 155 in-lbs in an alternating sequence to keep the pressure equalized.
25. The rotor should sit flush against the axle flange. Our Currie 9-inch studs had shoulders that were a bit too large for the rotor and required a very slight enlargement with a drill press. It’s not an issue since the rotors are hub-centric, like newer Mustangs with sealed hubs.
26. After installing the caliper adapter and shimming per the instructions the caliper is slid over the mounting bolts and secured with lock nuts. It should be centered over the rotor, but 0.015 shims are included to adjust it. We went with a four-piston caliper that visually matches our front six-piston; the caliper body is the same.
27. The next way we verify the caliper mount is by removing the center bridge and sliding the Wilwood pads into place. They should slip in without resistance and be centered side-to-side. Ours went together with zero adjustments necessary. Be careful to not over-tighten the center bridge when reinstalling; it only needs to be snug.
28. Wilwood’s rear brake kits are available with a new parking brake cable kit that we highly recommend. Though it can be installed in multiple ways, Gil opted to follow the original mounting style that works best with the stock lever.
29. The parking brake shoes are adjusted by removing the dust cover and turning the star wheel with a brake shoe adjustment tool, or a flat screwdriver. The shoes should be expanded until a slight drag is felt when spinning the rotor.
30. Unfortunately, the stock rear axle lines are routed for drum brakes, so they would not work in our case. Fortunately, Gil is excellent at forming custom lines and whipped up two new ones that roughly mimic the stock routing, but met up with the Wilwood calipers. We also added a new stock rear brake hose as well.
31. With a new 1350 U-joint installed on the original driveshaft, a new set of U-bolts were used to install it to the Currie yoke.
32. Now we still have the vintage Shelby look of our Vintage Wheels Works V50 wheels, but with modern stopping power. Paired with the 200 treadwear Nitto NT05s, we should have a very potent braking package.
33. The result: 135.3 feet 60-to-0! That’s 75 feet sooner than previous! We’re pretty sure it can do better since the very worn-out suspension nosedived so hard under threshold braking that it felt like we were doing a stoppie! With only the lap belts currently installed, we had to fight to keep ourselves off the steering wheel against the 1g peak and 0.9g average. These numbers will only improve as we upgrade our suspension!