Roadie rear end

[a400man]

I have a 94 RMS and the rear end blew up on me. I was thinking about finding a rear end out of a car with disk brakes, so my question is what kind of cars are basically a direct bolt in besides b-bodys? I don't care if it's the same gear ratio or not because I can always retune the computer. What is the width of the whole assembly if anyone knows? Thanks.

 

[The Roadagon]

As far as I am concerned,I think you are over simplifying the project.
My Wife uses terms like ,rip it out or slap it on,anyone that has worked on cars or trucks knows it aint that easy. Remember you will need the upper and lower suspension arms or links to bolt up to the brackets that are welded
to the rear housing,if the new rear housing dosent have those brakets
already there it becomes quite a project to position them properly. There
are many variables other than the gear ratio that could make this project
not work. Just for starters the universal joints must be the same or you will need to modify them, the width of the rear will have to be similar, brake hose
locations will need to be close,your suspension brackets will need to match up with your four link and on and on. I recommend you get a rear that you know will install under your car without major modifications,that is unless you are a glutton for punishment! Oh and I forgot to mention the axle and stud
position must be the same as your current wheels or you will have to get a new set or rear wheels.Need I say more. ed

 

[Buffman]

go find a 9c1 caprice with disc's (8.5" 10 bolt) or a impala ss and call it day.

 

[MrBuick (Magnum)]

The only B-body's that came with rear disc brakes were 94-96 Caprice 9C1(police car), and 94-96 Impala SS. The 9C1 rear is the same width as the RMS rear. The gear ratio will be 3.08 with an LT1, or 3.23 with an L99(4.3). I found 3 9C1's with the disc setup still on the axle, in the past week. 2 of them are in the same yard. I can see there was a 3rd, but somebody got all the goods before me. So you know, you can bolt the disc baking plates, and hardware to virtually any of the 8.5" sedan axles. I found a rear in the yard from a 92 Caprice 9C1, that has 3.42 posi. I found another that is a 3.08 blown posi with disc brakes. I plan on swapping the disc setup to the 3.42 rear, then returning the 3.08 rear with the drum brakes put back on. Unless everything looks really good. Then I will keep it.

Can't have too many 8.5" rears around! Figured I would toss the 3.42 posi rear with discs under my Jesus Roadmaster, while I rebuild the very low rust axle that is in it. 3.42 is likely the best gear for a highway cruiser. Which is what I plan on doing with it.

 

[Ozzy]

The only B-body's that came with rear disc brakes were 94-96 Caprice 9C1(police car), and 94-96 Impala SS. The 9C1 rear is the same width as the RMS rear. The gear ratio will be 3.08 with an LT1, or 3.23 with an L99(4.3). I found 3 9C1's with the disc setup still on the axle, in the past week. 2 of them are in the same yard. I can see there was a 3rd, but somebody got all the goods before me. So you know, you can bolt the disc baking plates, and hardware to virtually any of the 8.5" sedan axles. I found a rear in the yard from a 92 Caprice 9C1, that has 3.42 posi. I found another that is a 3.08 blown posi with disc brakes. I plan on swapping the disc setup to the 3.42 rear, then returning the 3.08 rear with the drum brakes put back on. Unless everything looks really good. Then I will keep it.

Can't have too many 8.5" rears around! Figured I would toss the 3.42 posi rear with discs under my Jesus Roadmaster, while I rebuild the very low rust axle that is in it. 3.42 is likely the best gear for a highway cruiser. Which is what I plan on doing with it.

But can you turn 1000-1100 RPM at 45 MPH 😀

 

[dedwood]

Will the 9C1 rear disc brake setup bolt on to the 91-96 RMW?????

 

[MrBuick (Magnum)]

But can you turn 1000-1100 RPM at 45 MPH 😀

No... But tell me... who the hell wants to do that anyways?? If I really want to, I can get the 95 Red RMS out with the 2.56's. 😱

I pulled that 92 Caprice 9C1 axle today. 3.42's, working posi. Looks like it needs new seals. It might be shot all together. But I won't know until I get it apart this week. I went next for a 96 Caprice 9C1 rear. When I got to the car, a guy had just started working on it, and said e was taking the whole rear. So I ended my dad at that. I mean, I pulled an LT1 out of a 94 Roadmaster already that day. 😀 It took me 5 hours to pull the LT1, and rear end. This includes the 30 minutes I spent pushing the engine to the front of the yard, loading it and repacking the bed of the truck. The rear end came out REALLY quick. This was the first time I had removed one, and not cut the control arms. I still hacked the parking brake off... but they freeze up on Michigan cars anyways.

So I'd say, the swap of a rear axle is not very hard.

Will the 9C1 rear disc brake setup bolt on to the 91-96 RMW?????

Nope, not gonna happen. The problem is, the Wagon axle tubes maintain a 3" diameter. The Sedan tubes neck down a few inches before the bearing. If you look it up, a sedan, and wagon use different outer wheel bearings and seals. This is because the Wagon bearing outer diameter is larger. A few guys have put a 9C1/SS rear under a wagon. BUT, this isn't exactly ideal. It will all bolt up, if you force it. The lower control arm mounts are spread a little farther apart vs a sedan. The spring perches are also shifted slightly outward. Then you have to factor in the Width difference. A Roadmaster Sedan / Caprice 9C1 width is 1566mm. A Caprice Sedan(Towing package, with an 8.5" rear), and Impala SS are 1598mm wide. Then the wagons are 1656mm or so. Somewhere around there.

 

[The Roadagon]

I am pretty sure the answer is no. The Wagon rear is about 2 inches wider
than the sedan. The wagon rear also uses larger axle bearings than the
Sedan. As I understand it the wagon backing plates are larger then the sedans,so a sedan drum brake or disc brake set up will not fit on a wagon drum brake set up. For my wagons rear brake set up ,I used a set of good grade riveted brake shoes, replaced all the old springs and pins and got the drums
turned down about .020". Along with a good set of front disc pads and rotors my wagon stops very well ,that is for a 4600 lb car. ed

 

[The Roadagon]

So Cory,If the wagons rear differential is about 90mm wider than the sedans'
differential(tow package) than the wagons overall rear width is about 3.5"
wider than the sedans. Personally I dont like the idea of using a sedan
rear housing even if it has discs under a wagon. I think there are just to many
ugly dimensions to deal with. And I dont think those small rotors and pads would be much more effective than a set of good drums! ed

 

[HOTROD333]

go find a 9c1 caprice with disc's (8.5" 10 bolt) or a impala ss and call it day.

NO NO THERE IS A 3 1/2 " DIFFERENCE FOR THE WAGONS