Rear End Ratios

[martine]

im trying to figure out what my rear end ratio for the 66 delta88 425/superrocket 2-barrell as well as the 65 delta also.remember these cars i have are all 4-doors.and if there were two or more different rear ends in these years please tell me.also i need to know this because im not getting off the line like my 65.and they are exackly the same cars.often these cars were often neglected when it came to servicing the rear end.so please help.thanks

[foureverolds8]

Do you have the numbers off the rearend? Try looking into oldsfaqs..
http://www.442.com/oldsfaq/ofdif.htm#Differentials
or
http://www.novaresource.org/axle.htm
Hope it helps

[Edsdelta]

Martine,

I was able to find a 12-bolt 4:10 rear that came off a 66 Starfire. This will replace my single-track rear that I've currently got in my 66 Delta.

The question is, is yours single track or POSI? Single track will give you more top-end and better gas milage. The 4:10 I'll be putting in will give me a better jump and run off the line, though my gas milage will suffer more.

[martine]

thanks ed.i have a single track.definitely not posi.which i wish i had.good find.if you could point me in the right direction to a posi or which other oldsmobile i could transfer it from.i would highly appreciate it.thanks!!!!!!!

[Nebrask Olds Fan]

I'm not exactly sure what your wanting to do here, but any rear axle from any GM A body car will fit in these babys, and I've heard that the rears from the G bodys will also fit. If the tag is gone from the rear cover, the best way to tell what the ratio is is to count the teeth. Easy check for posi rear is jack up one side and try to turn the wheel, if it don't turn, it's a posi, if it turns, it's open.

[Edsdelta]

Finding the Rear end was pretty hard. It's actually a 3:08. I posted a wanted ad on ebay (they happened to take it down and got all pissed) but had a few people that were able to help me out.

I've spent about $800 so far gutting out a Starfire in MI, including the rear end and complete A/C setup. So, you'll have to be putting hours upon hours months upon months finding hard parts such as this.

A good place to start is google.com. I will be making a Salvage Yard Locator section here next.

Ed

[kevin]

Not fer nothin' here friends, but a posi rear will turn with one wheel on the ground. The easiest way to tell if it's a posi is to jack up both rear wheels and turn one. If the other one turns in the same direction as the one you're turning then it's a posi. If it turns in the opposite direction of the one you're turning then it's not a posi. That simple. While you've got it up there, you can turn one wheel one revolution and count the number of times the driveshaft turns, which will give you a rough idea of your gear ratio. Of course, if it's not a posi, then the wheel opposite the drive wheel must be on the ground.

[jdorour]

Hi Guys.
This may be late but...
Sorry but Nebrask Olds Fan is wrong. An axle from an A or G body will not fit B and C Body Cars. In the 60's all the divisions used different axles Olds used TYPE O units.

If you lok at the axle tube on the right side you will find a two leter code. Post the code and I will get the specs for you.

[monzaz]

That is correct a-g body rears will NOT fit full size cars from the 60's a-g body rear really do not even interchange with out modifications too. Jim

J D Race

[Olds64]

Check the following websites for rear end gears and differentials.

http://www.drivetrainspecialists.com.../gm/index.html

http://www.rearsgears.com/home.html

[monzaz]

The rear he has does not have any aftermarket gear support. Sorry. The 'O' type is a-body not full size which is what he is looking for. The only fullsize rear that has any aftermarket support in gears is the Corperate 8.5 10 bolt thAT STARTED IN 1971 IMPALA AND 1973 AND UP gm OLDS BUICK PONTIAC ETC. ALL THE WAY TO 1996 WHEN FULL SIZE RWD CARS KIND OF ENDED WITH STRAIGHT AXLES ANYWAY. jIM

WWW.JDRACE.COM

[Olds64]

I don't understand rear ends very well; however, the second web link does give full support to ALOT of Oldsmobile rear ends. They have a big stock of older cars as I understand it.

[monzaz]

The stock you will get for your car will most likely be used. Which is fine as long as it is good. Make sure they send pictures for any used products.

Gasser olds/pontiac front loaders are supported here and there. But the rear you are looking for I am pretty certain ...unless you have a GM NOS part laying around there will be NO aftermarket support for the rear you are doing.

12 bolt A-body olds gears have 3 gear sets 342 390 410 Richmond gear.

Gasser stuff - drop out rieder racing mark williams etc still have gears but they are usually race ratios like 390- and up.

I clicked on gevo's olds stuff on the site and nothing came up. ??? Maybe I will call and see what he has because I have a few gasser pig noses I still need to build here. I will ask him and see if he knows anything about this rear and its available parts. Jim

[joe_padavano]

I'm coming in late here, but this thread seems to have a LOT of bad information. First, the Delta 88 is a B-body. The rear axle is wider than on an A-body. They are NOT interchangeable. Second, I'm at a loss to understand why a non-posi should have any better or worse gas mileage than a posi axle. When you're moving, both tires are turning and the posi has no impact. If the original post was referring to the minor friction between the two sides of the differential when cornering, I'll admit that there is some, but it's such a small amount that you'd be hard-pressed to measure the difference.

[88 coupe]

Originally Posted by joe_padavano

I'm coming in late here ........

Since it is a 5 year old thread, should we consider "late" a relative term?

Norm

[monzaz]

were not trying to put a a body rear under his b-body car. He is looking at A-body 'o' type gears thinking they will fit his 'o' type full size rear. THEY are not the same. full size 'o' type rears are 12 bolt guts a-body 'o' type guts are 10 bolt. They have aftermarket 'o' type a-body gears ...but as fart as i know at this moment in time there are NO full size b-body 'o' type gears on the market. JUST nos stock gears. wow I hope that clears the air...lol.

As for the gas mileage thing...I think your reading into that thread too far. I am sure the open rear that is being replaced in the above thread was a freeway gear and the posi was a steeper gear. and was wondering if the gear change was going to make a difference. Probably but will never know how much cause the original ratio was never provided.

Just because a thread is old does not mean it can not help someone into the future. Besides it got alot of people talking right brainstorm it and will get the right info HOPEFULLY. ? Jim

[88 coupe]

Originally Posted by monzaz

........ Just because a thread is old does not mean it can not help someone ........

Five years has to be some kind of a record.

........ it got alot of people talking ........

Yes. A lot of people who thought they were replying to a new thread.

Resurrection of an old thread, is considered a breach of etiquette on any message board. If one wishes to continue an old discussion, the protocol is to start a new thread. If that policy is not recognized on this board, I'm sure someone will correct me.

While we are waiting for a reply, consider rereading the following post:

http://classicoldsmobile.com/forums/...html#post16260

Then, if you have not deleted it, you can reread the PM that followed it.

If you have any questions, or wish to discuss it further, send me a PM.

Norm