JY cars with rear 4-lug discs?

mob

the guy who hits on his mom
20+ Year Stangneter :roc</strong><span class=
Oct 3, 2003
2,566
136
104
Dallas, TX
Hey guys, I dont want to go 5-lug because the cost of wheels and tires is where it gets expensive. I want to stick with 4-lug but I am wondering if there are any cars in the junkyard that I can take some rear disc brakes off of? What all would I need to make it work? I really hate having drums in the rear, so old school. I have 2 JY's around me with good inventory and are cheap.
 
These are 4 lug 10" vented rotors. This is a great swap if you can find the whole rear end! It is a 8.8" rear end, and the stock gear ratio is 3.55 for the manuals, 3.73 for the autos on the Turbo Coupes, and 3.08 on the 93 Cobra. Keep in mind the axle is .75" wider than the stock Mustangs, you will need to adapt the brake lines fittings. The easiest way is to use the drum brake rear hardlines and adapt at the caliper softlines. You need to drill the quad shock mounting holes 2" lower on the T-bird axle for the Mustang. For E-Brake cables, you need to purchase use the FMS cables. If you have a '93 vintage, you need to use the '93 Cobra cables. Ford made the '93 E-Brake cables like the Sn95 units with a center mounting in the tranny tunnel. 93 Cobra E-Brake cable #F3ZZ-2A635-A.

If you cannot get the whole axle or do not want it, get all the brake lines, calipers, bolts, rotors and axles. Then swap this into your existing axle. Here is a parts list that you need to do the swap from the '87-88 Thunderbird Turbo Coupe or '93 Cobra:


10" 4 lug vented rotors
rear calipers
rear caliper brackets
Axles -- if you use the stock caliper brackets. They are 3/4" wider than the stock '87-93 units.
soft brake lines
(2)FMS M-2809-A ebrake cables for '87-92 cars, '93 Cobra units for '93 year cars
(1) FMS M-2810-A center Ebrake cable

FMS M2450-A proportioning valve solid end cap
Adjustable proportioning valve
new 2 port 4 wheel disc master cylinder (1" bore for stock front calipers or 1 1/16" for the 73mm fronts)
3-2 port master cylinder conversion. Click here to Order
2 adapter fittings to use the stock drum brake hardline with the softlines - Click here to Order

The discontinued Ford M-2300-C kits uses the same calipers and rotors from the 87-88 Turbo Coupe, but stock length axles. SSBC and other companies have picked up this Ford kit and sell them for about $600. If you can get the calipers and rotors, but not the axles or axle brackets, call North RaceCars for these brackets! These will allow you to use the stock length rear axles with the TC rear disc parts!
 
Slightly different version from above. I have actaully done the swap, so it's not just a copy from somewhere else and paste here...

Been there and done that! With success! :nice:

Do the 87-88 T-Bird Turbo Coupe rear end swap!

Auto trans 87-88 Tbird Turbo Coupes come with 3.73 gears and manual Turbo Coupes come with 3.55 gears.
Both rear ends are 8.8 units with traction lock.
Cost is $125-$300 for the rear axle. Add another $100-$200 or so to complete the brake upgrade.

I choose 3.55 since I do more highway driving. Both ratios have 10 5/16" disk brakes with vented rotors as standard equipment.

It takes 2 guys the first day to get the old rear end out and the new one bolted in place.
It takes 1 guy another whole day to do the brakes.
This tech note was written for 87-93 model 5.0 Mustangs, so if you have a 4 cylinder conversion or earlier model, there may be some other changes needed as well.. See 87-93 Mustang 5.0 Brake upgrade pages. Improve your 60-0 times! for more information.
You will need a several sets of fittings, I recommend that you get them from Matt90GT's website,
87-93 Mustang 5.0 Brake upgrade pages. Improve your 60-0 times!.
Read Matt's instructions thoroughly, everything you need to know about the brakes is all there.
You need to be patient and follow all the internal links, and there are many of them.

You will need 2 fittings in the rear to adapt your old brake tubing to the TC disk brakes.
The fittings go between the steel tube and the caliper brake hose.
You will need another set of fittings to make a 2 port to 3 port adapter. To make life simpler,
just buy the kits from Matt. You could piece them together, but it's not worth the time unless
you work at an auto parts store with all the fittings ever made.

You will need to drill the quad shock mounting holes 2” below the holes drilled for the Turbo Coupe
mounting points. The bolts are metric, so don’t loose them or the nuts. A 15/32” drill should be
about the right size unless you have access to metric sized drill bits. Going without quad shocks is
not an option.

You will need a proportioning valve, Summit has one for $42 + shipping. Wildwood 260-8419
You will need a kit (FMS makes the part) to gut the stock proportioning valve, Summit also
has that, about $18. Ford Racing M-2450-A

You will need a new master cylinder, see Matt's site and make you choice. I used a 94-95 Mustang
master cylinder. Note that rebuilt 94-95 Mustang master cylinders do not come with a reservoir.
That means a trip to the junkyard and some more money spent.

Your brake pedal may be very hard and almost impossible to lock up the brakes. I had to replace
the front calipers with 73 mm calipers from a 91 Lincoln Mark 7 to get the braking performance up to par.

You can use the stock 5.0 booster if it is in good working condition. No need to replace the booster.

Bleeding the brakes will require 2 people and some coordinated effort. I don’t recommend using your
wife or girlfriend to pump the pedal – they get offended when you yell at them. I used a homemade
power brake bleeder constructed from a garden sprayer and some fittings from Home Depot. It cost
about $25 and was worth every penny. See how hard is it to bleed brakes? - Mustang Forums at StangNet
for details and pictures.

See Mustang Central.net FMS M2300K Brake Install for help with the emergency brake. The red words
link to some very useful photos on how to modify the handle. The stock setup tends to lock up and not release properly.
All in all I have been very pleased with the results.

Turbo Coupe parts list:
87-88 Tbird Turbo coupe rear axle assembly.
94-95 Mustang Master Cylinder with reservoir
Brake line Adapter fittings 87-93 Mustang 5.0 Brake upgrade pages. Improve your 60-0 times!
3 line to 2 line brake fitting kit 87-93 Mustang 5.0 Brake upgrade pages. Improve your 60-0 times!.
proportioning valve, Wildwood 260-8419 Summit or Jegs
Kit to gut the stock proportioning valve Ford Racing M-2450-A Summit or Jegs
Reuse stock brake booster
73 mm front calipers from a 91 Lincoln Mark 7 (two calipers) local auto parts
Emergency brake cable parts Summit or Jegs or .late model restoration
M-2809-A* Parking Brake Cable (need 2)
M-2810-A* Parking Brake Cable (short cable that attaches to the parking brake handle)

I recommend that you use reman calipers and use the calipers from the Turbo Coupe axle for cores to return.
The parking brake mechanism and the caliper slides tend to lockup and freeze.

Identifying a Turbo Coupe rear axle:
1.) Measure the rotors - a TC disk brake uses 10 5/16" vented rotors.
2.) Measure the length of the quad shock mount arm and compare it to the mount on your existing stock axle.
The TC quad shock mount arm is about 8" long if I remember correctly.
3.) Measure the distance between the axle flanges and compare it to stock. The TC rear axle assembly is
3/4" wider per side, or 1 1/2" wider for both sides.

Five lug Turbo Coupe conversion:
Use the 94-98 axles Mustang axles. Use 1990 Mazda MPV 3.0 V6 front rotors (10", 5 lug x 4.5" pattern, 2 7/16" offset ). While you are at the auto parts store, set a TC rear rotor side by side with the Mazda rotor and they are the same except for the offset.

The next step fixes the offset problem:
Use a Maximum MotorSports 1/8 spacer (MMWS6, Maximum Motorsports, the Latemodel Mustang Performance Suspension Leader! ) between the inside of the rotor and the axle flange. The spacers may need to have the OD machined to fit properly. The stock rotor offset is 2 5/16" and the Mazda rotors are 2 7/16" offset. The 1/8" spacer puts the rotor back dead center alignment with the calipers.

The Mazda rotors are under $30 each, and I have seen them for $20 each. The MM spacers are two for $30 + $9 shipping. So the entire package costs $99. That saves $41, which most of us could find a very good use for.
 
What about a Mark VII rear end? is it the same as a t-bird? Would you have to use different offset wheels like the Fox body Saleens had? Just wondering cause I have a rear end out of a Mark VII, it has a bent axle. Was going to use the brackets and flip them but just put the Ford racing drum kit on my car.
 
What about a Mark VII rear end? is it the same as a t-bird? Would you have to use different offset wheels like the Fox body Saleens had? Just wondering cause I have a rear end out of a Mark VII, it has a bent axle. Was going to use the brackets and flip them but just put the Ford racing drum kit on my car.


Mark 7 rear is not the same as a tbird. It's 5 lug, uses 11.35" rotors, 54mm calipers and is wider 1.25" each side.

The t bird is 4 lug, 10.5" rotors, 45mm calipers and wider 0.75" each side
 
Jeez, I guess it would be easier to just go 5 lug if I want discs all around.
Just do the 87-88 Tbird Turbo coupe rear axle $180 at a pick n pull EASY TO DO Here is mne
0201101502a-1.webp

0201101502c-1.webp
 
I looked at buying the parts seperately at advance auto online.. They have sales all the time online only.. A 20% off sale might have just ended..it looked like it was gonna cost around 400 for the brackets (150) and all the parts from advance.. Which I thought was pretty cheap..