I've read much on TGO and am grateful for all the good tech info. You've helped me solve many problems. I've never felt the need to start a thread until now. https://www.thirdgen.org/forums/imag...s/thumbsup.gif

Here's my question:

I need to rebuild the differential. When we dropped the driveshaft, my mechanic showed me the sloppy play in the pinion yoke - so I know it's time. My uncertainty is whether to stay with the current 3:08 and the existing Eaton posi or change to 3.23 or 3.42 which will require changing from 2 series posi to 3 series. It is my daily driver and not destined for the track, though I do enjoy pounding wannabees at a stoplight. I figure the 3.42 would be better but will cost me 2 mpgs. Thinking the 3.23, which would give a little better punch, but only be a 5% loss in mileage. I realize that the speedometer gear will need to be replaced if I change gears.

My car is 26 years old, and I don't want to go through the trouble of replacing my 3.08 gears with new bearings while keeping the 26 yr old potentially unreliable Eaton posi. I'm thinking 'all new'. So, in your experience, would it be better to go with all new? Or is it reasonable to expect that the stock posi will continue to last (half the cost)? What would you recommend?

 

I think you have the Eaton Posi mixed up with the Auburn. Your car will have the Auburn unless someone changed it. Either way it goes, Eaton doesn't make a 2 series, so I doubt that you have an Eaton.


The 3.42 is a very popular gear with the 700R4 transmission. I don't know that your fuel mileage will change that much. It might even get better if you drive in town a lot.


The Eaton Posi is a very good and popular upgrade for the 3rd gen Camaro. If you want to save just a little bit of money then the Yukon Dura Grip is also a good differential. There is also the Eaton Truetrac, and if you want a used differential and have 28 spline axles you can get a Torsen. Just don't use another Auburn.

 

Thanks. I do drive in town 60% of the time and felt that the 3.42 would be a good choice though I have the stock manual transmission.

I seriously thought the cars were shipped with Eaton posi. Yeah, from what I've read here about Auburns, the choice is pretty clear. 26 spline was stock for the 2 series, correct?

 

The Eaton Posi was never factory installed in a 7.5 rear end.


They were all 26 spline through '89, then they were all 28 spline.

 

Eaton DOES make carrier 2 26spline, I have a truetrac carrier 2 (#911A415) waiting at the post office right now and I'm gonna pick it up tomorrow. And it will work with 3.42 thick aftermarket gears, I was told by Jim at jdrace&restoration. I will install this in my axle this weekend.

 

The Eaton Posi is not available in a 2 series. I was not aware that the Eaton Truetrac is available in a 2 series. That's good to know.

 

Crap, missed the posi part...for once I felt smart but then it came back and kicked me in the nuts

Yeah I'm sooo excited to see how the truetrac works and how it drives with 3.42 and all the winterrepairs I did. My car felt like a boat on the road due to the bushings worn out, but now I got polys for it now so I hope it will be like an iron on the road.