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Topic: Rear Disc Conversion (Read 1854 times) previous topic - next topic

Rear Disc Conversion

Good Morning Everyone,
I'm thinking about swapping the drums in my 85 Tbird to disc and have been looking at kits.  I may go 5 lug, may not - that really depends on the practicality of the matter.  Anyway, has anyone else done drum to disc and if so did you buy a kit, which kit...and were there any unexpected issues that maybe the kit didn't cover (i.e. master cylinder, proportioning valve, etc.)?
Any guidance here would be a huge plus.  Thanks.

Rear Disc Conversion

Reply #1 –
I went to discs on my Cougar but I just took the easy route and swapped in a Turbo Coupe rear.
1986 Mercury Cougar - 2.3T/T5 swap, TC brakes and suspension and rearend, 3" exhaust, 255 lph fuel pump, Stinger BOV, Gillis MBC @ 18 psi
2003 Chevy Suburban Z71 - Daily driver
2015 Chevy Volt - Wife's daily driver

Rear Disc Conversion

Reply #2 –
The search feature can be your best friend on most subjects. :D


86' T/C 4.6L DOHC
16' Chebby Cruze 1.4L Turbo
17’ Peterbilt 389 600hp 1850ftlb Trq 18spd

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“Heavy Metal Mistress”
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Rear Disc Conversion

Reply #3 –
I just did it last Sunday. Still gotta hook up the emergency brake cables. They are already hooked up to the rear calipers. Just gotta run the cable to the foot lever in the car and route them.

I used a Turbo Coupe rear (1988), Smaller Fox Cobra Mustang booster (mine was 30 years old, needed to go), and a Cobra Master cylinder with a Maximum Motorsport brake line adapter kit along with a Turbo Coupe proportioning valve. I also installed the TC front brakes as well.

I'll post pics tomorrow evening.
'88 Sport--T-5,MGW shifter,Trick Flow R intake,Ed Curtis cam,Trick Flow heads,Scorpion rockers,75mm Accufab t-body,3G,mini starter,Taurus fan,BBK long tube headers,O/R H-Pipe, Flowamaster Super 44's, deep and deeper Cobra R wheels, Mass Air and 24's,8.8 with 3.73's,140 mph speedo,Mach 1 chin spoiler,SN-95 springs,CHE control arms,aluminum drive shaft and a lot more..

Rear Disc Conversion

Reply #4 –
Quote from: Clatonious;461643
Good Morning Everyone,
I'm thinking about swapping the drums in my 85 Tbird to disc and have been looking at kits.  I may go 5 lug, may not - that really depends on the practicality of the matter.  Anyway, has anyone else done drum to disc and if so did you buy a kit, which kit...and were there any unexpected issues that maybe the kit didn't cover (i.e. master cylinder, proportioning valve, etc.)?
Any guidance here would be a huge plus.  Thanks.

Whichever way you decide to go, try to stick with Ford parts.

I bought an aftermarket disk brake kit for my Maverick off of the Summit demo rack only to find out it was missing several pieces. When I tried to procure them, I found out that the pieces I needed were NOT available individually. In other words, the kit was useless and Summit took it back, despite their policy on demo purchases. The point of this is that parts break and/or wear out at some point. No matter how good it may have functioned, you are dead in the water if you can't buy replacement parts.
1986 Thunderbird Elan 5.0 EFI AOD, 3.73:1 SN95 rear, 17" Mustang Bullitts w/Firestone WO Indy 500's. Future plan: 349 stroker, C9 block, forged dish pistons, Scat 9000 crank, 4340 I beam rods, ARP head/main studs, ported explorer intake, 1.72 CC RR, Vortech V2 supercharger, Mr. Freeze Meth Inj, intercooler, TFS 190 11R CNC heads (66CC), BBK shorties with 2.5" duals, 4R70W Transmission, Taurus fan.

Rear Disc Conversion

Reply #5 –
If you decide to go five lug just get a 94-98 SN95 rear end and call it a day.  The 7.5 will hold quite a bit of power but if you want an 8.8 it will have to come out of a V8 car.  These are the correct width and literally bolt in.  Do a search if you are interested in this route.

83 351W TKO'd T-Bird on the bottle


93 331 Mustang Coupe - 368 rwhp

Rear Disc Conversion

Reply #6 –
I'm sticking with 4 lug. I like my wheels, and my tires seem big enough. I use 275-40-17 in the rear and 255-40-17 up front. Can't see any reason to go to five lug if I like my wheels.
'88 Sport--T-5,MGW shifter,Trick Flow R intake,Ed Curtis cam,Trick Flow heads,Scorpion rockers,75mm Accufab t-body,3G,mini starter,Taurus fan,BBK long tube headers,O/R H-Pipe, Flowamaster Super 44's, deep and deeper Cobra R wheels, Mass Air and 24's,8.8 with 3.73's,140 mph speedo,Mach 1 chin spoiler,SN-95 springs,CHE control arms,aluminum drive shaft and a lot more..

Rear Disc Conversion

Reply #7 –
Was referring to the Ops quandary on going to five lug but yeah your wheels look awesome on your car Vin.

83 351W TKO'd T-Bird on the bottle


93 331 Mustang Coupe - 368 rwhp

Rear Disc Conversion

Reply #8 –
Vinnie,
so you worked in your original drum ebrake cables into  your rear calipers first? worked your way up towards the Ebrake pedal which now you have to retrofit ?
My oldest son is working his existing drum brake e brake cable "with" the pedal hooked up.

are you saying you used your original "REAR" drum brake cables and was sucessfull in having enough slack to connect them to the rear caliper lever and the "eye" the cable locks into?

also,,
why use a prop valve when you have 4 wheel disc?
prop valve seems only useful for when you have front disc / rear drum???????

Rear Disc Conversion

Reply #9 –
I used the Turbo Coupe parking brake cables from the pedal all the way to the brake calipers. None of the original cables remained.

What I installed.....

-Front control arms
-Front spindles
-New MOOG ball joints
-Front struts
-Front calipers
-All bearings and seals were replaced with new parts from Ford Racing for the front and rear
-New tie rod ends (the rack was kept as it was still virtually new)
-All of the parking brake cable assembly
-Rear end (8.8 with 3.73 gears)
-Differential girdle
-New splash shields for the rear. NOS shields as mine were bent
-Drilled and slotted rotors front and rear
-New rear calipers
New rear caliper brackets
-All new fasteners for the calipers and brackets front and rear
-All new brake hoses
-New smaller Cobra Mustang brake booster
-New SN-95 mustang master cylinder
-Maximum Motorsports brake line adapter
-Turbo Coupe proportioning valve

The Turbo Coupes had a proportioning valve from the factory. I'd assume even with rear discs, there's still a braking balance that needs to be kept, so, I used it instead of the drum brake proportioning valve. Everything seems to be working fine so far now that I got the parking brake cable adjusted correctly.

Only issue I have now, which really isn't an issue.....the front brake line that goes from the front top of the proportioning valve to the front side of the master cylinder .....my line was not in good shape, so, I got a splice for the line and used two lines to make one. I now have the line in minty condition from an SN-95 car to use, so I'll swap that out as soon as time allows. As for now, no leaks, no issues. No modifications, all bolt in.
'88 Sport--T-5,MGW shifter,Trick Flow R intake,Ed Curtis cam,Trick Flow heads,Scorpion rockers,75mm Accufab t-body,3G,mini starter,Taurus fan,BBK long tube headers,O/R H-Pipe, Flowamaster Super 44's, deep and deeper Cobra R wheels, Mass Air and 24's,8.8 with 3.73's,140 mph speedo,Mach 1 chin spoiler,SN-95 springs,CHE control arms,aluminum drive shaft and a lot more..