roadmaster rear 8.5"?

So at my buddys junk yard, he has a 96 roadmaster lt1 sedan. He has no keys so I cant get in the trunk to check the rpo codes, but generally, what did these come with for gear sets and were they posi units if they had lt1s?

Also, its the 8.5" ring gear right? (i didnt have time to jack it up and look at the rear cover, so I cant tell until tomorow).

It has the rear sway bar, but thats all i really noticed. I didnt even check if it hyas disc, but the price is right so I am gunna pull it tomorow.

All Roadies had the LT1. All wagons did too.

Now for the specs I'm a bit hazy. If I remember the SS and 9c1's are the cars that had disks and the rest got 9" or 11" drums. Same for the posi with the SS and 9c1 getting it while the rest typically didn't. The gearing is generally going to be in the neighborhood of 2.93:1

Without checking codes or taking things apart I'd assume it has 2.93 with 11" drums and non-posi. It may have more to it, but don't pay for something based on what it may have

Copied all this stuff, so credit to Bill & Joel

Chevy
91-92 sedan
1566mm - narrow (all)

93-96 sedan
1566mm - narrow (9C1 - disc & drum & some other drum applications)
1598mm - wide (Impala SS - disc & B4U - drum)

Buick 91-96 & Fleetwood 93-96 sedans
1566mm - narrow (all)
NOTE: Fleetwood housing is unique to the application - 4-channel ABS provisions

91-96 wagon, all
1642.5mm

All 93-96 7.625" (ring gear) housings are 1598mm wide (Chevy sedan only)

Sedan housings, in both widths, have the same lower control arm bracket location/spread distance, and will fit any other sedan frame.
Wagons have a wider spread distance (approx. 2") between lower control arm brackets on housing, and corresponding wider frame lower control arm mounts.
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Parts listed are applicable to 94-96 B-body sedans, some may be applicable to 91-93 models.

Note: information posted is as found on manufacturer/supplier websites.
There ARE errors--some listings show NARROW housing axles as fitting Impala SS, which is incorrect--as relates to PRODUCTION configuration.

GM PART # 26038684
GM LIST: $328.83
DEALER COST: $194.93
DESCRIPTION: SHAFT,R/A - Caprice 9C1 w/rear disc (8.5/30 narrow)

GM PART # 26018080
GM LIST: $249.19
DEALER COST: $147.72
DESCRIPTION: SHAFT,R/A - Caprice sedan, Buick Roadmaster sedan w/rear drum (8.5/30 narrow)

GM PART # 26043164
GM LIST: $353.88
DEALER COST: $209.78
DESCRIPTION: SHAFT,R/A - Impala SS - rear disc (8.5/30 wide)
NOTE can be used in place of 26033203 on B4U Caprice applications (26033203 discontinued)

Above info from GM PARTS DIRECT


AFTERMARKET (listed alphabetically)

DORMAN (enter OE part number 26018080)
630-117 narrow sedan axle 1996-91 Chevrolet Caprice, 1996-91 Buick Roadmaster, 1996-94 Impala SS (incorrect)
Direct OE Cross - Click here for more information
OE#: 26018080
OE Manufacturer: GENERAL MOTORS


MOSER - 8.5" / 30-spline applications
A103001 - WIDE sedan housing
A103005 - NARROW sedan housing


SUPERIOR
Superior Axle and Gear PA5856 - sedan narrow application only


TOM'S DIFFERENTIALS
KAC10-A21 30-1/2" 30-spline (narrow sedan housing) (replaces GM axle shaft 26018080 or 26038684)
KAC10-A23 31-1/16" 30-spline (wide sedan housing) (replaces GM axle shaft 26033203 or 26043164)


YUKON
26043164 (Impala SS & B4U Caprice - "wide" 8.5" / 30-spline)
26018080 (Caprice/Roadmaster sedan - "narrow" 8.5" / 30-spline) or 26038684
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Stock '94-96 Caprice and Roadmaster sedans and wagons came with 2.56 gears as a base and 2.93 gears were an option.

Stock '94-96 Caprice 9C1s and Impala SS's came with 3.08.

Limited slip differential option (code G80 on the Service Parts ID sticker (SPID)) is an Auburn oem-style differential that is non-rebuildable.
Aftermarket Auburn differentials are rebuildable by Auburn through an exchange program.
The differential is an 8.5" style with 30-spline axles.

Not sure about what the Cadillac Fleetwood came with.

Good info guys...

There were two other roadies next to it that were tbi...not lt1....

Also, if it matters its an limited model with a swaybar

bfurches wrote:

So at my buddys junk yard, he has a 96 roadmaster lt1 sedan. He has no keys so I cant get in the trunk to check the rpo codes, but generally, what did these come with for gear sets and were they posi units if they had lt1s?

Also, its the 8.5" ring gear right? (i didnt have time to jack it up and look at the rear cover, so I cant tell until tomorow).

It has the rear sway bar, but thats all i really noticed. I didnt even check if it hyas disc, but the price is right so I am gunna pull it tomorow.

My 96 RMS Limited has a 2.56 RATIO with a G80....this is a non tow pack FE1 softride...if this info at all helps lol

Not sure if your looking for a set of gears from a Roadmaster or not, however, I do have a nice posi Auburn unit 2:56 gears out of a 95 Roadmaster. Just under 70K on them when replaced with an Easton posi unit with 4:11s. Not even sure of the value.

Larry

bfurches wrote:

So at my buddys junk yard, he has a 96 roadmaster lt1 sedan. He has no keys so I cant get in the trunk to check the rpo codes, but generally, what did these come with for gear sets and were they posi units if they had lt1s?

Also, its the 8.5" ring gear right? (i didnt have time to jack it up and look at the rear cover, so I cant tell until tomorow).

It has the rear sway bar, but thats all i really noticed. I didnt even check if it hyas disc, but the price is right so I am gunna pull it tomorow.

Is that the green limited Roadmaster at Center? If not, where is this car and how is the interior?

If it has 2.56 gears it is a 7.5 housing. If 2.93 it would be a 8.5

IMPALADAKID wrote:

If it has 2.56 gears it is a 7.5 housing. If 2.93 it would be a 8.5

3.23's have an 8.5 too right? At least thats what my FSM says for my car...

Cadet57 wrote:

IMPALADAKID wrote:

If it has 2.56 gears it is a 7.5 housing. If 2.93 it would be a 8.5

3.23's have an 8.5 too right? At least thats what my FSM says for my car...

Yup.

IMPALADAKID wrote:

Cadet57 wrote:

IMPALADAKID wrote:

If it has 2.56 gears it is a 7.5 housing. If 2.93 it would be a 8.5

3.23's have an 8.5 too right? At least thats what my FSM says for my car...

Yup.

Now I hate to derail a thread with my own rambling.... Which is why I am going to

Can someone teach the noobie the difference between the different gear ratios and their different uses? IE, why do I have 3.23's in my car?

Cadet57 wrote:

IMPALADAKID wrote:

Cadet57 wrote:

IMPALADAKID wrote:

If it has 2.56 gears it is a 7.5 housing. If 2.93 it would be a 8.5

3.23's have an 8.5 too right? At least thats what my FSM says for my car...

Yup.

Now I hate to derail a thread with my own rambling.... Which is why I am going to

Can someone teach the noobie the difference between the different gear ratios and their different uses? IE, why do I have 3.23's in my car?

Less torque requires more gear, as does tow package. Your car is a 305, and needs more gear to get it going.

IMPALADAKID wrote:

Cadet57 wrote:

IMPALADAKID wrote:

Cadet57 wrote:

IMPALADAKID wrote:

If it has 2.56 gears it is a 7.5 housing. If 2.93 it would be a 8.5

3.23's have an 8.5 too right? At least thats what my FSM says for my car...

Yup.

Now I hate to derail a thread with my own rambling.... Which is why I am going to

Can someone teach the noobie the difference between the different gear ratios and their different uses? IE, why do I have 3.23's in my car?

Less torque requires more gear, as does tow package. Your car is a 305, and needs more gear to get it going.

Actually, mine's a 350. It has the GU5 3.23, and a G80 posi plus G67 springs. I dunno if the guy just kept checking all the boxes at the dealer or what lol.

My Caprice has the wide rear axle, but I guess it's a 7.5? It's a 2.56 open, but the car is a 305.

My brothers '94 RMS is the 2.56 G80, but it has a trailer tow package on it, which is strange.

Matt Trakker wrote:

My Caprice has the wide rear axle, but I guess it's a 7.5? It's a 2.56 open, but the car is a 305.

My brothers '94 RMS is the 2.56 G80, but it has a trailer tow package on it, which is strange.

That is wierd. The posi was optional with all but the Impala, and not available with the fleetwood, but the 2.93 is the standard gear with the tow package.

IMPALADAKID wrote:

Matt Trakker wrote:

My Caprice has the wide rear axle, but I guess it's a 7.5? It's a 2.56 open, but the car is a 305.

My brothers '94 RMS is the 2.56 G80, but it has a trailer tow package on it, which is strange.

That is wierd. The posi was optional with all but the Impala, and not available with the fleetwood, but the 2.93 is the standard gear with the tow package.

The car has a lot of random options. "Supposedly", the guy who originally owned it worked for GM and special ordered it with a bunch of things, then somehow oversaw them building the car, I don't know how true that is though. According to that VIN decoder site it was one of two built just like it, lol.

I suppose I will find out tomorow morning lol.

Yea justin, its the greenish blue one up at center. They have two more parked next to it. I think I am going to grab the plastic fuel tank out of her too (still fills behind the license plate just like my boxy

Well, i lucked out. The rear was an 8.5 posi with 2.93 gears, 11 drums, and included sway bar and wheels/ tires for 150.
Had 110k on the clock.

bfurches wrote:

Well, i lucked out. The rear was an 8.5 posi with 2.93 gears, 11 drums, and included sway bar and wheels/ tires for 150.
Had 110k on the clock.

Hmmm. Any of them have good interiors? Hopefully gray... I've been itching for some RM seats.

bfurches wrote:

Well, i lucked out. The rear was an 8.5 posi with 2.93 gears, 11 drums, and included sway bar and wheels/ tires for 150.
Had 110k on the clock.

That's a good deal. If I could find a deal half as good as that I'd jump on it for my car. Seems all I find are rotten housings for $300 bucks

taking a break from the swap and waiting for my other set of hands to get here, but here are some pics...



...new rear all cleaned up and quick paint. I pulled the cover and checked the carrier and gears, put a newer cover/ hardware on it, replaced the fluid and swapped my stainless braided lines over.



Old housing ripped out and ready for a make-over. Im going to strip the housing tomorrow and send it out to have the tubes welded and the housing powder coated. The ends weren't as bad as I thought, just the bearing...So i will use the roadie housing temporarily while I build this one...




damage from the axle snapping. Notice the half dollar size holes in the wheel well


...its gunna suck for now with these 2.93's....but at least its only temporary...