rear axle I.d.

**Supersport0126** · 09-17-2011, 04:54 AM

Could someone please tell which digit on v.i.n. Is your rear axle?, and whatever digit it is, whats the ratio? Thanks! Its a 98 camaro ss!

**Knight** · 09-17-2011, 05:01 AM

There are RPO codes on the driver's door that give the code for the factory installed gear ratio -

GU2 - 2.73 's Standard auto trans gear ratio. also note on the A4' s (auto's) shifter console if the gear selector for 1 is missing.

GU3 - 3.08 's V6 gear ratio

GU5 - 3.23 's Optional auto trans gear ratio

GU6 - 3.42 's Standard manual trans gear ratio

All came with the 7.5"/7.65" 10 bolt rear differential with 28 spline axles.

Hope this helps.

**Supersport0126** · 09-17-2011, 05:49 AM

Yes thanks a lot man!

**Knight** · 09-17-2011, 06:14 AM

**TLS_Addict** · 09-17-2011, 12:07 PM

Originally Posted by Knight

There are RPO codes on the driver's door that give the code for the factory installed gear ratio -

GU2 - 2.73 's Standard auto trans gear ratio. also note on the A4' s (auto's) shifter console if the gear selector for 1 is missing.

My car is a GU2 code car and it has the gear selector for 1st gear.

So is that a one year only deal or something?

Also, if he is an SS with an A4 he has the GU5 3.23 code.

**Knight** · 09-17-2011, 02:18 PM

Honestly, I just copied the codes from a database. I don't follow much with the auto trannys, as I don't have one. It's quite possible it was only done for one year, maybe even the earlier ones.

**35th-ANV-SS** · 09-19-2011, 06:31 AM

You can also jack the rear end up (securely) and crawl under the car and mark the drive-shaft with a marker. After you have the drive-shaft marked, turn the rear wheel (1) full revolution and watch/count how many times the drive-shaft turns.

If the drive-shaft turns 3.5 times, you have a 3.42 rear end ratio. If the drive-shaft turns 3.25 times, you have a 3.23 ratio. If it turns 4X, you have a 4.10/4.11 ratio.

You get the idea

**TLS_Addict** · 09-21-2011, 06:42 PM

If it spins and the wheels dont move it means you need a new rear. lol

**konigandy6** · 09-22-2011, 04:52 AM

Originally Posted by TLS_Addict

If it spins and the wheels dont move it means you need a new rear. lol

Which is an inevitability with the 10 bolt.

**TLS_Addict** · 09-22-2011, 08:52 AM

Not if you dont drive it. lol I can hear it now "The 10-bolt in my 2002 Z28 was so weak I was in the garage looking and the car and thinking about drag racing and it broke!"

**2002ssslp** · 09-28-2011, 02:49 PM

Why did GM put such a small rear in the SS and WS6 ? How much more would it have cost to put in a 12 bolt ? I know I can get a Strange 12 bolt or 9" for less then 2k and it would have been much less for the for GM at the time of build. My 02 SS was almost 33k when new so what is another 800 bucks ?

**35th-ANV-SS** · 09-28-2011, 03:11 PM

Originally Posted by 2002ssslp

Why did GM put such a small rear in the SS and WS6 ? How much more would it have cost to put in a 12 bolt ? I know I can get a Strange 12 bolt or 9" for less then 2k and it would have been much less for the for GM at the time of build. My 02 SS was almost 33k when new so what is another 800 bucks ?

OEM 10 bolts replacements (refurbished) from a junk yard go for around $500. You can typically find them from first party sellers for between $150-$400.

A new 12 bolt/9" is going to run anywhere between $2,500 to $3,500...depending on what options you get.

If you can find one cheaper, I'd buy it personally.

**pajeff02** · 09-28-2011, 06:21 PM

Moser 12 bolt with a True Trac, 33 spline axles, 4 channel, welded relocation brackets and sway bar brackets was $2,800 back in 2009.

**35th-ANV-SS** · 09-28-2011, 06:35 PM

My 9" was $2500 with the True Trac, 31 spline axles, 4 channel with ABS, and welded relocation brackets. I didn't get the sway bar brackets though. Probably should have, but the stock unit clears OK. I will get them when I get an aftermarket sway bar though.

**2002ssslp** · 09-28-2011, 07:38 PM

I still like the old Dana 60. Does anyone know if that chunk will fit the F-body platform ?

**35th-ANV-SS** · 09-28-2011, 07:45 PM

Pretty sure people here have it, but I don't know if it's a true bolt on like the other rear ends are. I know for certain that you have to get a new drive shaft with it because it needs to be about 1.5" shorter. It's also the heaviest and least efficienct of the 3. Unless you're going crazy HP wise, I think the 12 bolt or 9" works just fine.

**pajeff02** · 09-29-2011, 03:13 AM

Strange has a lightweight version of the Dana called the "S60" that fits our cars. Comes in at around 20-25 lbs. heavier than a 12 bolt.

**2002ssslp** · 09-29-2011, 05:28 AM

Not going to go crazy HP but I do have heads and a cam in my future so I think I will stick with the GM theme and go with a 12 bolt which is what it should have had in the first place. I had Dana's in the past and never broke one even with a built Hemi engine and a 4 speed trans. You are right about the weight, HEAVY.

**konigandy6** · 09-29-2011, 06:57 AM

Originally Posted by 2002ssslp

Not going to go crazy HP but I do have heads and a cam in my future so I think I will stick with the GM theme and go with a 12 bolt which is what it should have had in the first place. I had Dana's in the past and never broke one even with a built Hemi engine and a 4 speed trans. You are right about the weight, HEAVY.

A good rule of thumb to follow, is A4 go with a 12 bolt and M6 go with a 9". The 12 bolt is the most efficient rear out of them, but I have heard stories of them breaking in an M6 car because you can't pre-load the drivetrain when launching. The 9" is the indestructible answer since the carrier is free floating. Don't get me wrong, you can still rock a 12 bolt in an M6 car and it will be stronger than the 10. But like I said... I did a bit of research before I bought my axle and chose the 9".

**2002ssslp** · 09-29-2011, 04:27 PM

Thanks for the info. I think I may do the rear swap before I do the cam and heads.How about the setup. I currently have about 350rwhp since the car has just bolt ons and runs mid to high 12's @ 110'ish. Cam and heads should give me another 100hp so What should I do to the suspension to get it ready for the HP increase and the 9" rear. I have already put in the 1LE bars with poly bushings and bilstein shocks, I also have 3 pt. SFC.