I have a 1987 Iroc-Z with a 305 TPI. I believe my gears are 2.73. If I wish to put 3.23 gears what do I exactly need to get?

I plan to swap a 350 TPI really soon so would those gears run well with a 350?

One last question, will I be able to remove it off any Camaro with those gears?

Thanks

 

You are going to need a 3 series differential. The 2.73 is on a 2 series and the 3.23 uses a 3 series. You will also need a good installation kit.

 

So I need a whole new differential with the gears in it already?

 

You don't need a complete rear end, just the 3 series differential. The differential is the part that the ring gear bolts to and the axles go in it.

This is a 3 series Eaton Posi differential for the Chevy 12 bolt. Just an example.

 

Some questions may be answered from the sticky:

https://www.thirdgen.org/forums/tran...-10-bolts.html

JamesC

 

Alright thanks. So would you guys recommend 3.23 or 3.73 gears?

Does this mean I can get the differential off a 4th gen?

 

Yes. You might consider reading the sticky, if you haven't already.

JamesC

 

You can get the differential from any 7.5 10 bolt GM rear end, from an S10 truck to a Malibu or Cutlass. You must get one with the correect splines for the axles that you are using. The early ones had 26 splines and the later had 28. I recommend getting a new Eaton Posi. These were never used by GM in the 7.5, but are probably the best street/strip differential for the GM rear ends.

 

Ok thanks. Would you recommend upgrading my gears?

 

Many of the 4X4 S10 trucks had 3.42 or 3.73 gears, and some had the 4.10. You can get the gears from one of these and get a differential from a Camaro or Trans Am. Just be sure that you get the 3 series with the correct splines. If you have the money then get new parts. The new Eaton is much better than any of the GM differentials and new gears are much easier to set up. Get a quality installation kit no matter which way you go.

 

Oh alright thanks for the advice.

 

The gears depend alot on the tire size and tranny. If you are running stock tire size with the 700r4 automatic I would recommend 3.42 unless you do a lot of highway then I'd go with 3.23. Personally I wouldn't do 3.73 or higher with that 700r4 but I know other would disagree.

 

BTW, the L69 came with a manual and OE 3.73's. In 84 (the only year, IIRC), the L69 was backed with an auto tranny and 3.42's.

JamesC

 

Well I have 20 inch Irocs so what would you recommend?

 

It depends. What's the tire size? What transmission do you have?

 

245/35/20 with a 700r4

 

With those taller tires I'd say go with 3.42 for sure or maybe even step up to 3.73 unless your on the interstate a lot.

With 3.42 you'd be at 2000 rpm at 65 mph and 2300 rpm at 75 mph.
With 3.73 you'd be at 2100 rpm at 64 mph and 2500 rpm at 75 mph.

Use the gear calculator below for more help. Select 93-97 f-body A4 for transmission type and enter tire size.

http://www.f-body.org/gears/

 

Oh alright thanks.