Rear Disk Brake Conversion Questions

7173Mustangs.com

Help Support 7173Mustangs.com:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

red73mustang

Well-known member
Joined
Jan 21, 2013
Messages
61
Reaction score
1
Location
New Jersey
My Car
1973 Mustang Convertable
Ok, as you may know I have a 73 convertible with a 6 cylinder rear end which I suspect is an 8 inch model? I'm planning to do a big block motor swap so I will likely need another rear to handle the added torque. Since I need a new rear I may as well add disk brakes. I think there are bolt on kits available and I have heard of guys using rears from Lincoln Versailles units. What are some other rear disk conversion ideas that would include the rear? Cost affective ideas (read cheap) welcome!

Regards, Chet

 
Wow, Crown vics are everywhere! Never would have thought of that. Is there alot involved in this kind of swap (welding of any mounting brackets?)

 
An 8.8 wouldn't be a bad idea. You can find mustang brakes all day long. My supercharged 393w made over 500lb/ft if torque at the wheels and it handled it just fine. Of course I had forged axles. My '68 coupe has a 9" rear with a set of Willwood disk brakes (I actually prefer Bear Brakes like I have in the front but the parking brake always seems to bind up). I would look at those two options. Price both and go with the least expensive.

If you're going for mor than 500 lbs of torque, you may opt for the 9 inch. The 8.8 with forged axles is very strong, but the 9in is tough to beat.

 
I am running an 8.8 out of an explorer sport trac. It came from factory with 3.73 posi and disc brakes. I got mine for free from a buddy but can be had at local bone yard pretty cheap. Explorers are everywhere and a lot of them are already disc brakes. My old motor was around 400hp and had no troubles with it the last 3 years. My new 408 will be between 500-600hp so I will probably end up braking something if it ever hooks up but we will find out this summer. The rearends are very close in width and the rim bolt pattern are same as ours. You will have to cut off the spring perches and weld new ones on in the correct position and also have to have your driveshaft cut down a bit I think. I had my driveshaft modified for around $150 and balanced at a local shop. I think it is definitely a good bang for your buck. If you have some mechanical and fabricating skills its a pretty straight forward swap. If you have any other questions about it let me know. One of the better mods I have made to my mustang.

 
I am running an 8.8 out of an explorer sport trac. It came from factory with 3.73 posi and disc brakes. I got mine for free from a buddy but can be had at local bone yard pretty cheap. Explorers are everywhere and a lot of them are already disc brakes. My old motor was around 400hp and had no troubles with it the last 3 years. My new 408 will be between 500-600hp so I will probably end up braking something if it ever hooks up but we will find out this summer. The rearends are very close in width and the rim bolt pattern are same as ours. You will have to cut off the spring perches and weld new ones on in the correct position and also have to have your driveshaft cut down a bit I think. I had my driveshaft modified for around $150 and balanced at a local shop. I think it is definitely a good bang for your buck. If you have some mechanical and fabricating skills its a pretty straight forward swap. If you have any other questions about it let me know. One of the better mods I have made to my mustang.
+1 I've been thinking about this set up as well from past turtle post's- I like the trifecta for the cost -great gear ratio, disk and posi traction win win win

 
If you're concerned about strength, I would weld the axle tubes (they are pressed in) and go with a forged 31 spline axle. Mine were good for over 550rwhp. But I was also setup for road racing.

 
a good way to go is a 94-04 mustang gt or cobra brakes. street or track makes the cobra conversion and fits on 8 or 9 inch diffs. there is another company that does the gt brakes.

its inexpensive to go with late model mustang brakes cuz there i no custom pads or rotors.

 
I forgot to mention, I did weld the axle tubes all the way around the housing. Not sure what hp they are good for but I have beat on mine pretty good with 400hp and no troubles at all. We will see what it does this summer. As far as the master cylinder and proportioning valve, I am still running the stock stuff. They say you should run an aftermarket prop valve, but I have no problems and it stops a whole lot better then it ever did before. The master cylinder is the stock manual drum brake one, but I will be swapping to the stock disc brake power set up soon. Its in the garage ,just haven't had the chance to put it in yet. The axle housing center section is offset slightly to one side but that doesn't seem to matter. I have no vibration or premature u joint wear. I have had the car north of 100mph several times with no vibrations. :D Also the explorer rears did come with 31 spline axles. The ranger were only 28. Heres a good write up about some specs and what it takes to swap it into another vehicle. This is for rangers, but gives you an idea. You don't have to worry about swapping shock mounts because ours are on the spring plates. Heres the link http://www.therangerstation.com/tech_library/Explorer8_8.html

Hope this helps ya out a little.

 
Last edited by a moderator:
Lots of great info here guys, I'm assuming that the Crown Vic rears are not off-set like the Explores are? (not that it would stop me from using one). Are the Vic units 8.8 inches and 3.73 ration like the Exploders with Traction Lok and will they accept the modern type Cobra roters and calipers and allow the use of a 15 inch Magnum 500 rim?

I've also located an early 90's Lincoln Town car for parts, same questions as above.

Regards, Chet

 
And having done the conversion with Baer ironsports, let me offer one final opinion

Unless you are going to autocross the car, the drum brakes will never present any difficulty. It is a pure appearance issue for all practical purposes and leaves you having to deal with replumbing your brakes and using a nonfactory set up for the braking system. It is expensive and I would never do it again!

but that's just me

 
And having done the conversion with Baer ironsports, let me offer one final opinion

Unless you are going to autocross the car, the drum brakes will never present any difficulty. It is a pure appearance issue for all practical purposes and leaves you having to deal with replumbing your brakes and using a nonfactory set up for the braking system. It is expensive and I would never do it again!

but that's just me
Really? I've been upgrading my suspension over the years and I find that the brakes, with sintered metal pads, stock size front rotors, and rear drums does a passable job of handling braking duties while driving, but it doesn't feel confident. I figured that a rear disc brake conversion might help with improving the repeatability of heavy braking. Sort of on the wall about it at the moment... I do lot of driving through the twisties (canyons mostly).

 
Back
Top