How do I find out what gears I have?
I got some casting numbers on the one side:0978 02890 731 and the other side BORG WARNER M19J8
Any links to where I can get info from these numbers?
This is a spare axle I got and dont have the build sheet from the car its from.

 

Casting numbers don't tell you anything.

Easiest way is to pull the cover off and count the teeth. You'll probably going to be putting new oil in it anyway.

There's a good chance it's only a 2.77 diff since those were the most common.

 

I guess thats the best and only way to tell, all I know is the axle is from an 89 GTA with 1LE package, not sure if its auto or 5spd.
I should prob stick with my 10-bolt with 3.42 gears and just get the plates to mounts the PBR brakes.

 

If it was from a GTA, it will probably have 3.27 gears.

 

The EASIEST way, does not include opening it, draining the oil & replacing the gasket.

The easiest way IS.....Jack it up....Put the tranny in Neutral....Spin a tire & axle & watch the driveshaft rotate.

If the tire make 2 3/4 rotations to 1 driveshaft rotation, its a 2.77.....
If the tire make 3 1/4 rotations to 1 driveshaft rotation, its a 3.37.....etc. etc.

No waste of gear oil...No buying of new axles...No counting teeth. Just much faster and easier.

Why do everyone want to do it the hard way & count gear teeth, then hafta look that up on a chart?

 

Your kidding right? A chart? Why a chart? What about using 2nd grade math, dividing the number of teeth on the ring gear by the number on teeth on the pinion? Works pretty well for most people.

 

You don't have to look it up on a chart. Divide the number on the ring gear by the number on the pinion gear. 41 teeth on the ring gear divided by 11 teeth on the pinion gear equals 3.7272, or 3.73.

You have your method backwards. You turn the wheel one turn and count the number of turns that the drive shaft makes. This is only true if you have a good working posi. If you have a standard differential or your posi slips a little bit then this will be way off. If both wheels turn EXACTLY one full trun then it is accurate. One turn of the wheels and 2 3/4 turns of the drive shaft equals 2.77 or 2.73, depending on the type of rear end. If you have a standard differential then you need to leave one wheel on the ground and turn the other one EXACTLY 2 full turns and count the number of turns that the drive shaft makes.

 

More often than not, the fluid hasn't been changed in a decade, so why not jerk the cover for the change, and since the numbers are stamped on the ring and pinion, take a peek. The following "chart" is for a 10-bolt, but it'll serve--now that I think about it, the "chart" may be the same for a 9-bolt:

41 : 15 = 2.73
41 : 14 = 2.93
40 : 13 = 3.08
42 : 13 = 3.23
41 : 12 = 3.42
41 : 11 = 3.73

Edit: see the post below for the 9-bolt ratios.

JamesC

 

You have your method backwards. You turn the wheel one turn and count the number of turns that the drive shaft makes. This is only true if you have a good working posi. If you have a standard differential or your posi slips a little bit then this will be way off. If both wheels turn EXACTLY one full trun then it is accurate. One turn of the wheels and 2 3/4 turns of the drive shaft equals 2.77 or 2.73, depending on the type of rear end. If you have a standard differential then you need to leave one wheel on the ground and turn the other one EXACTLY 2 full turns and count the number of turns that the drive shaft makes.
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http://www.camaros.net/showroom/data...l_DSC01029.JPG

 

And with the "turn the tire" method can you really determine with absolute accuracy if it's a 3.23, or a 3.42?

 

Wow....I needed THREE people to point out my tire vs driveshaft rotation counting.....,

I KNOW how to it....Just TYPED it backwards...Geez people, gimme a BREAK!

As for counting teeth vs counting rotations.....Its the difference between a jack & 5 min vs 30 min plus buying a new gasket....buying new oil....tools.....

My method is MUCH MUCH MUCH simpler & faster. I was just trying to point out the SIMPLEST way.

Like junkyard shopping...You REALLY wanna get under & do the teeth counting method, or counting rotations?

As for 3.23 vs 3.42 or 2.73 vs 2.77...A 2.77 or 3.23 would be a 10-BOLT anyways. 9-bolts have 2.77/3.27.....Can't count bolt heads & tell if it is a 9 or 10 bolt, yet you wanna count teeth? Not to mention,,,3 1/4 turn vs 3 1/5 turns. If you can't tell the difference between a quarter turn & a half turn...You have no business having tools in your hands to begin with.

Besides all that...How are you gonna count the teeth? Rotate the tire to turn the axle! If you hafta turn the tire ANYWAYS, just count it & never even get under the car!

If ya'll do it the hard way, be my guest...I'll keep doing the tire method & wrenching on other mods, while you're still under the car doing it the hard way, counting teeth & getting dirty.

 

Simplest perhaps, but the method leaves room for doubt (at least in my mind). Counting teeth and/or checking the ring and pinion for their numbers dismisses all doubt. What's a little dirt and grease to a car guy? I've had my say, I'm done.

JamesC

 

My method has never failed me...Not one time, and leaves me time to do other things.

 

Your method is just fine if done right. This is fine if you just want to find the gear ratio. On the other hand, if you want to know what differential is in it then you must remove the cover. The old "spin one wheel and see which way the other one spins" method is VERY unreliable. It's fooled me several times and I've been doing rear end work for over 28 years.

 

I took the cover off and counted the teeth: ring has 38 pin has 11.
By calculation it came out as 3.45, which is sweet and must of been from a 5spd GTA.
Numbers from the ring were: 0598-029010 BW CA 3 45 D
Thanks

 

Never mind that there is no 38 tooth, nor 11 tooth, nor 3.45 (which is a result of miscounting the teeth)....Yeah...I guess everybody was right, counting teeth is much more accurate.....

 

There's a 3.45.

JamesC

 

Yup.......and it seems 9bolt.com is having a special on 3.45 gear sets. Must have been a typo on their part since our 9 bolt authority says that ratio doesn't exist.

http://www.9bolt.com/

 

Best method is to check the ratio stamped on the OD of the drive gear. I belive the MFG will be stamping the correct numbers. :lmao

Also the axle housing is a Stamping, Diff Carrier is a Casting and the internal parts are a mix of Castings & Forgings.

 

Some pics:

 

Just an FYI: Glenn at http://www.9bolt.com/ confirmed that 3.45's are 38:11. I'll post the rest of the 9-bolt ratios in the FAQ section.

https://www.thirdgen.org/forums/faq-...now-about.html

JamesC