This thread is a work in progress. I've unlocked the thread for feedback and questions and if i've missed something or need to correct. I'm still adding/editing.
Wanted to make a new thread to replace the old thread which has info scattered around in many posts. Hoping to consolidate this down and make it more simple. Please limit this thread to discussion on the 5-lug swap, and any issues due to the swap, and not mechanical issues concerning brakes.
This thread will mostly detail the process of converting a Fox to 5-lug using a few methods, with a primary focus on SN95 style conversions. Sn95 parts are plentiful and readily available at most parts stores. The system is well balanced and there are three main setups.
Here are legacy instructions for the M-2300-K Cobra brake setup sold by Ford Racing in the late 90's and early 2000's. M-2300-K Instruction PDF This can be used as reference as it has part numbers for hardware. These instructions will pertain specifically to an Sn95 cobra setup, and are reference to the GT/V6 setup. I break out a parts list for the 3 main setups. Separate posts cover parking brake cables, 3-2 conversion, booster and other necessary info.
I wish i could put direct links to all the parts, but it changes almost daily.
Starting this thread with the hopes of reducing the number of 5-lug or general brake upgrade threads that have been appearing on the forums since most of the major brake conversion sites have gone down. This thread will be strictly informational, and any off-topic banter or user specific...
The simplest 5-lug conversion. This exists now in east to buy kits. For 87-93 V8 cars, they come equipped with 10.8" front rotors. You essentially only need to swap the rotors, the axle shafts and the drums.
If you want to purchase the parts separately, here is your list. Again, this is for 1987+ cars with the 10.8" rotors.
1984-1986 Mustang SVO or 1984-1990 Lincoln Mark rotors (abs or not does not matter)
1990 Ford Ranger 2.3L 5-lug drum 9"
For axles:
From an ‘83 to ‘92 4 cylinder or 3.0L V6 Ranger/Bronco II with a 7.5″ rear end you will need two driver’s side axles. Only the driver’s side will work as the pumpkin on these rear ends is offset and the axles are different lengths (you need the longer of the two axles). It should measure 29-5/32″. From an Aerostar you will need two of the passenger side axles from an 86 to 97 model.
For pre-87 cars and 87-93 2.3L cars, your front brakes are smaller. They are 10" brakes. The early 79-81 cars could come with even smaller (9" i believe) brakes. Unfortunately, no upgrade exists for the 9" brakes, you will need to upgrade. For guys with 10" rotors, your rear drum setup would be the same (works on 7.5" and 8.8 axles) Your front setup will differ in that you will now use the 10" 5-lug rotors off the same 2.3L ranger listed above. You may need to change out your bearings as well.
I would recommend if you have the 10" brakes to seek out 87+ V8 spindles and at least swap to the 10.8" brakes. You will need spindles, calipers, pads and brake lines. The calipers are both 60mm, so no MC changes needed.
Calipers (for informational purposes if you decide to build a custom setup)
The list of the calipers and their piston area sizes.
FRONTS
87-93 60mm calipers
-2827mm^2
-5654mm^2 for 2 calipers
SVO calipers: 73mm piston
-4185mm^2 each piston
-8370mm^2 for 2calipers
99-04 GT Front : 44.5mm pistons
-1555mm^2 each piston
-6220mm^2 for 2 calipers
99-04 COBRA 40.5mm pistons
-1288mm^2 each piston
-5152mm^2 for 2 calipers
94-98 COBRA 38mm pistons
-1134mm^2 each piston
-4536mm^2 for 2 calipers
94-98 GT/V6 calipers : 66mm piston
-3421mm^2 each piston
-6842mm^2 for 2 calipers
2000 Cobra R Front 36mm/40mm pistons
-2275mm^2 each caliper
-4550mm^2 for 2 calipers
GM C5/C6 front caliper 40.5mm/40.5mm pistons
-2576.5mm^2 for each caliper
-5153mm^2 for 2 calipers
GM ATS/XTS Brembo caliper 42mm x4 piston
-2771mm^2 for each caliper
-5542mm^2 for both fronts
Baer T4 Front caliper 1.625" (41.2mm) x 2 piston, 1.375" (35mm) x 2 piston
-2296mm^2 for each caliper
-4592mm^2 for both fronts
Baer 6P Front caliper 1.625" (41.2mm) x 2 piston, 1.375" (35mm) x 2 piston, 1.1875" (30mm) x 2pistons
-3010mm^2 for each caliper
-6020mm^2 for both fronts
(note, opposing piston, fixed calipers only get one side of the caliper factored in for surface area)
REAR
SVO REAR calipers: 54mm piston
-2290mm^2 each piston
-4580mm^2 for 2 calipers
94-04 rear calipers all : 38mm pistons
-1134mm^2
-2268mm^2 for 2 calipers
93-97 Taurus rear caliper (Must use SN95 Cobra abutments): 43mm piston
1452mm^2
2904mm^2 for 2 calipers
Grand Marquis Rear Calipers: 46mm piston
-1662mm^2
-3324mm^2 for 2 calipers
1993 Cobra/Mark7/T-bird 45mm rear calipers
-1590mm^2
-3180mm^2 for 2 calipers
Baer rear brake kit (93-97 Camaro calipers): 40.6mm single piston
-1295mm^2
-2590mm^2 for 2 calipers
If you want me to add any calipers..PM me
Top number is the area of each individual piston. Bottom number is all the pistons added up x 2 calipers. So simply add the bottom number from a set of front calipers, to the bottom number to a set of rear calipers and that is your total slave piston area in MM. Now divide that by the area of the master cylinder in MM^2 and you get your ratio.
The higher the ratio (17:1, 18:1, etc), the softer your pedal will be. The lower the ratio (11:1, 12:1) the harder the pedal will be. Now, if you elect to retain the stock Fox booster, you'll want a higher ratio number to compensate for the lact of assist. If you are lucky enough to run hydroboost, you can find that the extra assist allows you to use a ratio in the lower end of the range. Typically most of the factory setups fall in the 13:1 - 17:1 range (4-wheel disk). Again, i stress to research what other people are using and use this formula simply as a guide.
A lot of guys choose to simply upgrade the front brakes only, and run 5-lug drums. Which MC should they use? Well, compare the piston area sizes of the calipers you choose with those of the stock 60mm calipers, which offers a total area of 5654mm^2. If you increase the caliper size, you increase the piston area which in turn lowers the ratio since the MC has not changed. As a result, your pedal will be softer.
99-04 GT Front : 44.5mm pistons
-6220mm^2 x2 calipers
87-93 60mm calipers
-5654mm^2 x 2 calipers
99-04 COBRA 40.5mm pistons
-5152mm^2 x2 calipers
Depending on which direction you go, your pedal will be slightly harder or softer. In the above example, going with the 99=04 GT front calipers will make your pedal slightly softer due to the increase in piston area. While going with the 99-04 Cobra calipers will result in a slightly harder pedal due to the decrease in piston area. In this example, one may consider to compensate for the slightly harder pedal, by upgrading to a 1993 Cobra/94-95 SN95 booster.
Another common modification is to add 73mm calipers to a stock brake setup. Here you can see why this is bad.
87-93 60mm calipers
-5654mm^2 x 2 calipers
SVO calipers: 73mm piston
-8370mm^2 x2 calipers
As you can see, the caliper piston area is dramatically increased and will result in a solfter brake pedal. The danger here goes back to the lever example. Make the lever longer, and it will soon reach a point where you can't reach it because the stroke is so long. Same here. Since the caliper area increased, it makes the MC bore appear mathematically smaller when you calculate out the ratio. As a result, you run the risk of running out of brake travel to properly operate the pedal. In this situation, you may want to consider upsizing to one of the MC's listed above.
Hopefully this eductated you a bit on MC's and allows you to select the right one for your application
ALso, the brake pedal ration in the Fox cars is 3.5:1 in vacuum boosted operations. I beleive this to be true of 1987+ Mustangs. If converting to manual brakes, one needs to take into account the pedal ratio. Some kits out there modify the brake pedal ratio to compensate for the lack of assist. I suggest you research this as well as I beleive most of the manual brake kits out there make use of the 7/8" MC listed above as well as a different brake pedal ratio....just a heads up.
DISCLAIMER: The info provided is to the best of my knowlegde factual and accurate, but i make no garantees. Any info posted here is simply a guide for you to make an educated decision on your own. I claim no responsibility if you don't research properly and take your car up to 100MPH before testing the brakes out. Use at your own risk.
Calculator for Automotive and Racing Brake Systems, Master Cylinders, Brake Bias, Piston Area, CG Height, Weight Transfer, Pedal Stroke and Maximum Deceleration
Master Cylinder (for informational purposes if you decide to build a custom setup)
Brake hydraulics work similarly to the principles of leverage. You have the Master Cylinder, and the Slave Cylinders. The ratio between the two determines pedal effort. Easiest way to explain why you need to change your MC is to think of a lever. Say you have a fulcrum, a long lever and 500 pounds. We all learned in 1st grade the closer you move the fulcrum to the weight, the easier it is to lift the weight. This is equivalent to a smaller bore MC. The smaller the MC bore, the easier it is to operate the brakes (softer the pedal). Of course, a side effect is that now your lever is longer. The closer you move the fulcrum to the weight, the longer your stroke is to lift the weight. There will be a point where you simply cannot reach the lever, so you are unable to lift it. This is equivalent to decreasing the bore size of the MC so much that you can't operate the actual brake to MAX braking effort. The key here is to find a bore size that is small enough to reduce the work effort, but big enough that it will allow the brake to work to max potential.
Here are some of the more common Fox/Sn95 master cylinders
Final number is the bore area in millimeters squared.
79-86 Mustangs used SAE threading for the brake line fitting sizes. 87-04 Mustangs used metric. Maximum Motorsports sells 3-2 conversions for these master cylinders here. This will be covered as well in post #13
Easy answer is to simply look at what Ford did. When they put rear disks on the back of the Cobra, they upgraded the booster. All the vac boosted SN95's use a larger booster as well...so someone at Ford has determined a safe passenger car should use the upgraded booster. If you are running SN95 brakes all around, why not run the SN95 booster as well?
Options?? Either the 1993 Cobra Booster, or the 1994-1995 Sn95 booster. They are ALL 205mm tandem boosters, the main difference is the 1993 cobra booster uses the fox firewall bolt pattern and thread while the SN95 booster has a lug moved slightly and metric bolts. If you are buying new, get the 1993 Cobra booster if you can find one. If you look used, you can get 94-95 V6 boosters dirt cheap. Just be aware that you are using 14-year old used parts. If the MC was leaking at any point, there may be a good chance the booster is bad. The differences between SN95 v6, GT, and Cobra are negligible, so don't sweat using a V6 booster at all. For installation techniques, search the forums.
If you decide to retain the stock fox booster for whatever reason, at least make sure you are running the 87-93 Booster. To compensate for the lack of assist, you will want to run a slightly smaller bore MC as well. (more on that later). A 1/16" reduction from the recommended MC for a particular brake setup will result in a slightly softer pedal, with more pedal stroke. This increase in mechanical advantage will compensate for less vac assist.
Another option is to convert to Hydroboost like the 96+ V8 modular cars. It offers more assist than a vac booster. This thread will not cover the hydroboost conversion.
Please note: While manual brake options are also available, this thread will not be going into specific detail on these.
Weatherhead 7828 or this to adapter Sn95 specific lines to fox hard lines.
Rear parts needed
Axle brackets from 94-04 Mustang GT/V6 (this will give you SN95 offset which is 0.75" increase in track both sides)
Axle antimoans
94-98 Mustang axles (both 7.5 and 8.8 are the same)
dust shields F4ZZ-2C028-A
94-95 Mustang rear caliper soft lines
ANY 94-04 rear caliper pair (Cobra/GT or V6)
94-04 GT/V6 pads
94-04 GT/V6 rear rotors
Rear caliper adapter fittings to stock fox axle lines (MM version here, these are available at auto parts stores, i just don't have the proper size handy) OR change out lines to new SN95 caliper specific lines here or here
Weatherhead 7828 or this to adapter Sn95 specific lines to fox hard lines.
Rear parts needed
Axle brackets from 94-04 Mustang GT/V6 (this will give you SN95 offset which is 0.75" increase in track both sides)
Axle antimoans
94-98 Mustang axles (both 7.5 and 8.8 are the same)
dust shields F4ZZ-2C028-A
94-95 Mustang rear caliper soft lines
ANY 94-04 rear caliper pair (Cobra/GT or V6)
A pair of 7/16" E_clip retainers for the parking brake cables
94-04 GT/V6 pads
94-04 GT/V6 rear rotors
Rear caliper adapter fittings to stock fox axle lines (MM version here, these are available at auto parts stores, i just don't have the proper size handy) OR change out lines to new SN95 caliper specific lines here or here
Weatherhead 7828 or this to adapter Sn95 specific lines to fox hard lines.
Rear parts needed
Axle brackets from 94-98 Cobra, or 2001 Bullitt or 03/04 Mach 1 (this will give you SN95 offset which is 0.75" increase in track both sides)
Cobra-spec Axle antimoans
94-98 Mustang axles (both 7.5 and 8.8 are the same)
dust shields F4ZZ-2C028-A
94-95 Mustang rear caliper soft lines
94-04 rear caliper pair (need to be Cobra specific with regards to the pad support bracket)
Pair of 7/6" E_clip retaining clips for the parking brake cables
94-04 Cobra pads
94-04 Cobra 11.65" rear rotors
Rear caliper adapter fittings to stock fox axle lines (MM version here, these are available at auto parts stores, i just don't have the proper size handy) OR change out lines to new SN95 caliper specific lines here or here
Master Cylinder/Booster (see post #18 if you do not know what version cobra calipers you have)
If using 94-98 Cobra calipers, use a 94-95 Cobra Master Cylinder 15/16" bore
If using 99-04 Cobra calipers, us a 1993 Cobra 1" Bore
Ford still sells the old M-2300-M rear kit, which is essentially a rear Cobra disk brake setup minus the axles and Calipers/lines. It's expensive, but it's one stop shopping
This is a very uncommon rear disk setup. It was featured on the 91-92 Lincoln Mark 7, Late, 92-93 Saleens and the 1993 Cobra R.
This setup features a rear, vented 10.5" rotor, and the same 45mm piston rear caliper as the 1993 cobra. Axles are 0.75" longer and it's VERY similar to an SN95 brake setup and could easily be mistaken.
Unknown how much interchangeability there is. Once day I would like to test a theory and see if a 94-04 SN95 Gt/V6 caliper brackets and dust shields would work with a 1993 Mark 7 rotor and the 1993 cobra caliper. This has not been tested yet.
EDIT: discovered from someone who tried that it does not work. These parts are unique.
This has been a hot topic lately. Many many thanks to Alan H. (SVT_Alan) and Jojomofo21 for helping me with the info on this install. Alan posted a how to up on Facebook and he sent it to me since I am not on groups. This whole thing can be done for well under $500 and depending on what...
www.svtperformance.com
To summarize
For the front, you can use the standard Cobra 13" rotor. You will need to purchase a set of ATS brembo's with pads. You will also need to purchase a set of caliper inserts and rotor spacer from https://www.facebook.com/SSEngineeringLLC/. For brake lines, i would recommend aftermarket Sn95 SS lines
There is also a option to run 43mm calipers. For the vast majority of street cars, i would recommend sticking with the standard Cobra 38mm rear calipers. Increasing rear braking power can get you in trouble quickly on the street, so this is meant as an FYI. Please do your research before installing 43mm taurus calipers with ATS brembos or any larger than OEM front braking system. Do not install the 43mm rear calipers with any of the OEM brake choices listed elsewhere. Too much rear brake bias on a fox is a bad thing.
Ensure your 1987-1993 Fox Body Mustangs parking brake stays operational with this 5.0 Resto adjustable front parking brake cable. Available at LMR.com!
Buy part #M-2A635-6A Parking Brake Cable for (1993) Cobra w/ rear disc brakes for your classic 1993 Mustang from National Parts Depot. Free shipping on orders over $300, fast delivery & everyday low pricing! Order now!
The So I just put a 1998 Cobra leather handle in my car simply for the look. Learned a few things about the fox and SN95 handles. First off, there's no difference major differences in the87-93 and 94-98 handles. The 99-04s use a different mounting pattern (so I would recommend not using...
www.stangnet.com
As a final note, 94-98 SN95 handles will work in a fox. The cobra version is a nice leather wrapped version. 99+ handles are different and will not work. You still need to lock the adjuster on the sn95 handles as this was part of Fords recall. Tension adjustments will be made using the threaded center rod mostly.
With any of the above conversions, adapters need to be used to fit the different MC with your vehicle. The reason for this is the stock 87+ MC splits the front brakes up thru a separate port on the MC. The SN95 masters only have two outlet ports. Fortunately, Maximum Motorsports sells a number of adapters to make this easy. There are even adapters for the pre-87 cars which are already 2 port
The reason for going this route vs using the SN95 combo valve is because the weight of the fox as well as the weight distribution is not exactly the same. Plus, most owners are modifying their cars with bigger wider rubber out back, and/or slicks and skinnies and the OE factory proportioning may not be correct. In any case, being able to adjust will be beneficial.
I’ve often referenced this method, but never had pics. Until now. When converting to rear disk, or aftermarket disk brakes, one needs to change the MC from the factory 3-port MC to a 2-port variety. Max Motorsports sells a kit for this, but there is another method, that is somewhat cleaner...
www.stangnet.com
Prop valve plug
If you do go with a 3-2 conversion and retain the OEM combo valve, the front proportioning valve needs to be removed to gut the valve. Ford used to sell this as M-2450-A. A few vendors now reproduce it
You'll need this foxbody Mustang proportioning valve plug when converting your 79-93 Mustang to 4-wheel disc brakes. This seals the factory proportioning/combination valve. The original Ford part number is M-2450-A, but Ford no longer produces this. Fully machinedNew O-ringFull color...
When it comes to the 8.8 housing, there are generally 3 sets of 5-lug axle lengths. 86-93, 94-98 and 99-04. The main difference in the 8.8 axle is that the housing length changed in 1999. From 1986 thru 1998, the housing remained exactly the same. In 1999, ford increased the housing by 0.75" each side in addition to changing the mounting bolt size.
If you are changing your fox to Sn95 rear disks and want to use the OEM ford parts, you will need to use 94-98 axles. These axles will add an additional 0.75" of width to each side but will work with the factory ford rear caliper brackets.
You can also source fox-length axles. These axles are the same length as the 4-lug drum axle except they have 5-lugs. These might be ranger/aerostar axles, or aftermarket 5-lug axles. The axles can also be used with drum brakes, so you need to pay attention to the hub diameter. DRUM brakes require a 2.25" hub, while disk brakes need 2.5".
There are now some fox-length axles out there that feature the hub end for an SN95 rotor. Here is an example
Since these axles are now 0.75" inboard compared to SN95 axles, you will need a set of offset caliper brackets that match the brake setup you are trying to run. These offset brackets will pull the caliper mounting inboard by 3/4" allowing you to maintain your original rear track.
See here for brackets. These are also sold through LMR
There is a slight difference between the available SN95 spindles. The idea spindles to get in most cases is the 1994-1994 spindle. These are easily identified by a curved tie rod end and feature an F4Z7/F4Z8 or an F5Z7/F5Z8 part number
Maximum motorsports has a number of tech articles here on spindle differences, and why you should choose the 94-95 spindle over the 96-04 spindle
The steering arm of the 96+ spindle is 1.02" (26mm) lower than the 94-95 spindle
94-95 spindles increase front track by 0.120" (3.1mm) per side
96-04 spindles increase front track by 0.320" (8.1mm) per side
Since Sn95 spindles were designed for a car with longer control arms, they cause the camber settings to become more positive. 94-95 spindles will add 1.7 degrees of positive camber, and 96-04 spindles will add 1.3 degrees. Because of this, a good set of aftermarket caster/camber plates is recommended.
Ultimately, the reason to avoid 96+ spindles on a fox car with a stock K-member is due to the lowering of the tie rod arm on the spindle. On the 96+ cars, Ford lowered the steering rack down slightly for the 4.6L engine and compensated by dropping the tie rod mounts on the spindle down to match. If you put a set of 96+ spindles on a fox with stock K-member and the rack positioned higher in it's typical location, you will not be able to adjust the bumpsteer properly since the spindle tie rod mount and the steering rack's tie rod end would both need to occupy the same physical space. As a result, you will always have some degree of bumpsteer.
Cobra caliper differences & difference between Cobra and GT/V6 rear calipers
Cobra front caliper differences.
94-98 Cobra calipers used 38mm pistons. 99-04 Cobra calipers used 40.5mm pistons. Both mount the same and use the same pads and hardware. You just need to pay attention to sizing of the pistons for master cylinder selection.
Best way to tell is visually. The 94-98 caliper (red in below pic) has smaller pistons with additional ribbing around the bores. The 99-04 caliper has larger smooth bores
Rear calipers. Cobra vs GT/V6 calipers
All 94-04 Mustangs use the same rear 38mm varga caliper. The difference is the pad support bracket and the pad differences. The Cobra rotor are thicker, so the channel in which the rotor passes is larger to accommodate. The pads for the Cobra are also thinner to accommodate the thicker Cobra rotor. Cobra pad brackets also feature a support bar in the front
Again, the actual caliper is the same, the difference is this part here
How to select which Cobra calipers you should use?
Thread unlocked. I'm still chipping away at this so consider it a work in progress. But if folks spot errors or need to ask a question, you can do so here so I can edit or add info as needed.
You can take a chop saw with a metal cut off blade and widen v6 bracket to accommodate the cobra vented rotor.
I know if works for sure, as for when i did my disc swap way back, i had bought cobra rotors, but didn't fit.
The guy as northracecars suggested i do so instead of obtaining new rotors.
Just make sure you have a way to clamp the bracket down.
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