74 imp rear disks on 72 fury?

[flyinbrick68]

I've noticed in the for sale section a member had a 74 imp rear w disk brakes. Does anybody know the compatibility of that rear and the 8 3/4 rear that's in my fury? If the axles are the same flange/ bolt pattern should be a relatively straight forward updrade and swap? thanks guys...just asking because i seem to have poor luck w drum brakes.

 

[commando1]

Parts are hard to get for the Imp rear disk brakes. Bad choice for a swap.
There's no reason that your drum rear setup cant be made to work extremely well with a total rebuild. And a lot easier.

Posted via Topify on Android

 

[Badvert65]

I did this on a 74 Road Runner back in the 80's. It worked great at the time but I would shy away from it now as replacement parts are near impossible to get. I am talking about rotors, disc pads, hoses and the emergency brake shoes.
-Matt

 

[patrick66]

Check the width on a Grand Marquis/Crown Vic with rear discs. It's an 8.8" Ford rear, same bolt pattern as the Mopar, and parts are anywhere you want to look.

I know, Mopar purists will squawk and whine, but do you want something you'll be able to find parts for 30 years from now? Plus have superior stopping power? Check the Ford unit.

 

[thrashingcows]

Parts are hard to get for the Imp rear disk brakes. Bad choice for a swap.
There's no reason that your drum rear setup cant be made to work extremely well with a total rebuild. And a lot easier.

Posted via Topify on Android

I had bought all the parts for a rear disc swap on a 8 3/4 many years ago. Scarebird brackets, Lincoln rotors, Caddy calipers...etc, etc. Got tired of looking at all those parts on the shelf. So last year I decided to install it on the wagon. I have to say I'm less then impressed with it. Yes it kind of looks cool...but I'm seriously considering re-installing my good old reliable 2.5"x11" drums.

I know I would never install another rear disc set-up in any other vehicle.

 

[commando1]

a Grand Marquis/Crown Vic with rear discs...

That in itself is a tough find, yes?
Plus, won't you have to go to 17" wheels?

 

[flyinbrick68]

well i'm not real familiar with c bodies so i don't know about running that large of wheels.. I'm not ultra traditional I'm a younger guy, 32 so 17 inch rims wouldn't bother me. Wheels aren't in the budget.. and to be honest i'd rather swap the police wheels from the swepty to the furry. Then updrade the swepty with a larger wheel i kinda take a liking to the Hurst wheels.

 

[Mr C]

The 74 Imperial had the Chrysler 9.25 differential, the 8.75 has a totally different axle flange. Even though the bolt pattern is the same for the rim, the 9.25 caliper brackets for the Imperial will not fit on the 8.75...so this is NOT a bolt on swap. The only way to pull it off is to swap diffs...a lot of effort for marginal gain as the stock drums will work just fine.

 

[flyinbrick68]

I was wandering if that was the case...thank you for your info I think with some freshening they'll work fine.

 

[patrick66]

@Stan - A lot of the Panther-body cars have them. You want to use pre-1998 cars, because they still use a "normal" offset 15" wheel, versus the newer cars that have the different-offset 17" wheels.

 

[commando1]

I love this place.

 

[Carsavior]

I have the Imperial rear disc setup on my Challenger with a 8.75 rear. Been 12 years or so, seems I had to get the caliper adaptor machined somehow for a bolt to work right and had to take a set of front brake pads and grind a notch in them to make them work. Local brake supplier relined the parking brake shoes pretty cheap but I have never been able to get the parking brake to work just right. Working under the car right now- if I get the chance in the next day or so I'll try to take some pics.

 

[Badvert65]

The backing plate bolts on with 5 bolts. I had to leave one bolt out but the bolt pattern is exactly the same as on the 9 1/4 axle flange. I had to leave the bolt out that would have been on the top (12 o'clock) position (or maybe it was the bottom 6 o'clock position-I don't really remember exactly). The axle adjusters (8 3/4) work a little better if you add shims to account for the difference in the thickness of the brake backing plate. I did this exact swap back in the 1980's from an Imperial to an 8 3/4 rear and it worked great. I did use the imperial master cylinder and an adjustable proportioning valve. It was a fairly simple swap but the big problem will be master cylinder, pads, rotors, and emergency brake shoes. I still have a complete setup (less master cylinder) but I wouldn't consider it because of the lack of available replacement parts.

The 74 Imperial had the Chrysler 9.25 differential, the 8.75 has a totally different axle flange. Even though the bolt pattern is the same for the rim, the 9.25 caliper brackets for the Imperial will not fit on the 8.75...so this is NOT a bolt on swap. The only way to pull it off is to swap diffs...a lot of effort for marginal gain as the stock drums will work just fine.

 

[sa-noia]

The 74 Imperial had the Chrysler 9.25 differential, the 8.75 has a totally different axle flange. Even though the bolt pattern is the same for the rim, the 9.25 caliper brackets for the Imperial will not fit on the 8.75...so this is NOT a bolt on swap. The only way to pull it off is to swap diffs...a lot of effort for marginal gain as the stock drums will work just fine.

I must disagree, I did the swap from an Imperial 9 1/4" direct to my 8 3/4" Sport Fury housing directly...NO PROBLEMS...bolted up, no modifications at all. Everything fit. The only thing is the Imperial rear disc set up, it has one side facing forward and one facing to the rear. So if you dont get E-Brake cables from the Imperial, you will need two different lengths e-cables. All other stock components were used. The Imperial set up is very hard to find, they are out there, parts are available too. Calipers and pads are easy, remember to order two of the correct caliper, not a rt and left. They are the same caliper for both sides. By the way I used the 74 front disc brakes and spindles. They bolted in ball joint to ball joint. Remember that you will need an adjustable proportioning vallve for the brakes (front to rear) to prevent rear lock up.

 

[Mr C]

I must disagree, I did the swap from an Imperial 9 1/4" direct to my 8 3/4" Sport Fury housing directly...NO PROBLEMS...bolted up, no modifications at all. Everything fit. The only thing is the Imperial rear disc set up, it has one side facing forward and one facing to the rear. So if you dont get E-Brake cables from the Imperial, you will need two different lengths e-cables. All other stock components were used. The Imperial set up is very hard to find, they are out there, parts are available too. Calipers and pads are easy, remember to order two of the correct caliper, not a rt and left. They are the same caliper for both sides. By the way I used the 74 front disc brakes and spindles. They bolted in ball joint to ball joint. Remember that you will need an adjustable proportioning vallve for the brakes (front to rear) to prevent rear lock up.

If it bolted up without modification, you had an 8 1/4 diff. If you're trying to make it work WITHOUT modifications, then you're splaying the bolts and forcing things to fit. Like I said it's NOT a bolt on swap MODIFICATION required.

 

[sa-noia]

You are correct. I talked with my mechanic and asked again if he needed to do any drilling or modifications to install the Rear Discs from the Imperial. This time he stated that he did indeed had to drill a 5th hole and it wasn't quite as direct as I initially thought he said. I must appologize and say that there was work involved in mounting from a 9 1/4 " to an 8 3/4" housing. It is always easier when someone else does the work. Now I understand the details, there were items to overcome for it to work. Thanks for the "Flange Images" they helped me understand better also.

 

[sa-noia]

Mr C
Please send the "Flange Images" attachment to my email sa-noia@pacbell.net. Thanks in advance.

 

[Badvert65]

I am telling you, I put that setup on an 8 3/4 but I left out the bottom bolt. I have torn apart dozens of rear axles and I know what an 8 3/4 axle is and what a 9 1/4 axle is. Only trouble I ran into was with the factory end play adjuster on the 8 3/4. The drum brake backing plates are pretty thick and the adjusters were directly against the axle flange with the disc setup. It amounts to about 1/4 inch or so difference and the adjuster was maxed out until I had shims made to account for the difference. I drove it that way for years with out any issues. FYI, I am an old guy and I can't read the numbers on your flange chart. Any way you could email me a larger version?

 

[Badvert65]

Not really certain why I chimed in on this. I do not recommend this swap. IF I were to go with rear disk brakes, I would go with something from a late model - something with readily available parts.

I am telling you, I put that setup on an 8 3/4 but I left out the bottom bolt. I have torn apart dozens of rear axles and I know what an 8 3/4 axle is and what a 9 1/4 axle is. Only trouble I ran into was with the factory end play adjuster on the 8 3/4. The drum brake backing plates are pretty thick and the adjusters were directly against the axle flange with the disc setup. It amounts to about 1/4 inch or so difference and the adjuster was maxed out until I had shims made to account for the difference. I drove it that way for years with out any issues. FYI, I am an old guy and I can't read the numbers on your flange chart. Any way you could email me a larger version?

 

[commando1]

Leave the damn factory drum brakes on the rear (fully rebuilt, of course).
Why people want to make a camel out of a horse is beyond me.