Hi. Will be going to a ford 9 inch next year and need the width of the stock rear. Any ideas? Also anyone need a 12 bolt posi 3.08 gears,new clutches,painted,all new brakes? I'm in ct.

 

That 12 bolt of yours has a 1.6" pinion, and the 9" is only 1.3"

You could save a lot of money just converting your 12 bolt housing to bolt in style axles and using a cv yoke.

Just a thought.
I have no idea what you use the car for. Street, drag, etc.

 

Aren't olds rear ends with 12 bolt covers only 10 bolt at the ring gear? Like a 10 bolt carrier in a 12 bolt housing?

 

That's true for the 1967-1970 A-body Type O axles only.

On the other hand, the D88 axle is probably not a Chevy-style 12 bolt. The full size cars used a wide variety of unusual axles.

 

71 delta should have an 8&7/8" ring gear already. a 9" wouldn't be much of an upgrade for the cost in my opinion. The 9" is popular because you can swap out different gear ratios at the track. If you're not planning on messing with it all the time, you can save a buck or 2 by working with what you have.

A 12 bolt Olds full size should have a 10 bolt cover, with a 12 bolt ring gear.
Let us know what's currently under your car.

 

No it's a 12 bolt cover,had it apart so long ago I can't remember the ring gear count. Round cover,bolt in axles,clutch posi.and yes I do want to be able to change ratio's at the track.Once this is possible I will probably race the car more.

 

I have no idea.
I think B.O.P. full size cars had 10 bolt covers on everything.
The only one I remember having a 12 bolt cover is a chevy 12 bolt, but those have c clip axle retention, not bolt in.

 

So getting back to the question. What is the width of a full size olds rear end? I mean I can remove my wheels/drums and get the info. I just hoped someone might already have it.If not I'll get it. No problem;was just asking.

 

I would check out what you have first. I am "pretty" sure you have a "corporate" GM 12 bolt in there now. In 1971 Olds re-did the B/C bodies as did Buick. They called it the "G-ride." Front steering box, disc- brakes, yada-yada. Much better handling car. My 71 Delta conv (455- 2 barrel)has a 10 bolt cover read-end. I think it is a corporate GM 10 bolt 8.5. I also have a 4-door 1971 Delta parts car (was a 455-2barrel) that has the 10 bolt cover. I have a 1971 Olds 98 4-door which has the 4-barrel 455, it has a 12 bolt cover rear-end. I think it is a corporate GM 12 bolt. Check out what u have, if it's a corporate 12 bolt gearing is everywhere. You can have axles made fairly priced. I may be wrong but I wouldn't jump to a Ford 9" till I made sure about what u have. Good Luck, Ken

 

If it were a corporate gm rear it would have c clips right? mine is bolt in axles.Besides that I want to be able to go from 2.56 to 3.73 or 4.10. That way I can cruise at low rpm getting there-3.5 hours 1 way and change the pumpkin,have fun and change back for the ride home. I can also do the rear disc conversion easy by using circle track kits-stupid cheap.

 

I have a 75 Delta Convertible. It has the B.O.P rear (corporate gm rear). It doesn't have c-clip retention, it has bolt in axles.

 

Decided to go a differant route. going to use 195/50.15 tires. that way I can get near the gear I want for cheap. From 235/75/15 to 195/50/15. losing 4 inches of tire.We'll see if it works.Do me a favor and find me an article that states a gm "corporate" rear has bolt in axles. I've looked everywhere and have yet to find such information. Corporate means c clips as far as I've seen. love to find I'm wrong. that means there are gear kits out there for my rear. 3.27 here I come.

 

BOP is Buick Oldsmobile Pontiac. All three shared the same rear end, hence corporate rearend. Chevrolet Caprice and Impala has the Chevy rearend which uses the c-clips. The info was in my GM repair manual for 74 Oldsmobiles. The manual states directions to remove the axels by removing the c-clips if you had a Chevy rearend. If you had a BOP rear, it stated that it had bolts, hence different removal directions. If I had the manual with me, I'd scan it and show. But I'm overseas serving my country till midyear. Let me know if your plan works.

 

I measured the rear in my '71 from backing plate to backing plate and I want to say it was 62". The corporate rear everyone is talking about didn't come along in Olds till the late 70's. If it is a bolt in axle it is an Olds rear. What type of racing? Let us know what times you run.

 

Found out I can run a small diameter 15 tire on light rims and lose 4.5 inches of diameter thereby giving me a bunch more gear with my current setup. As soon as the engine is back in the car and tires bought,nos system setup will give times for 1/4 mile.Goal is mid 12's