GXP differential in a GT...

[johnbell2]

Re: what Eidolon said... my understanding is 3.23 rear is more the 'hot load' for the A6 on the GT as far as street work is concerned.

[Bonnetts02Vette]

I wonder why some people want even more after they've had the camaro 3.45 in their A6.

[skinsfangreg]

Skinsfan- the gxp 3.70 diff is completely different from the regular g8 diff. The gxp rear is just as strong as the camaro rear if not stronger. They are just like twice as expensive as the camaro diff new.

No true. The GXP rear is identical to the GT other than the ring and pinion are shot peened in the GXP rear. The camaro rear is about 25-30% bigger in actual size and from my research has better internals. By no means am I saying that the camaro diff is unbreakable but it IS stronger than the G8 diff. For normal driving either would probably be fine but for track use or higher horsepower applications the camaro diff is the better option. Gears can be had for the camaro diff for as low as $120 where it's unlikely you'll find gears for the G8 diff for under $600. I recommend doing some research.

Both camaro diff's can be had at the site below for right around $1k shipped.

http://wasslow.com/92246988-2010-11Camaro3.451CompletePositractionDifferential.aspx

[Bonnetts02Vette]

That I didn't know that. I was going for straight acceleration when I was going to put it in mine with the 3600 stall and cam.

[Devilish34]

find someone who "knows and understands " how to tune the trans

[I12XLR8]

find someone who "knows and understands " how to tune the trans

Anyone know if this includes Vector (from a distance?) I have no tuners around me...

[Bonnetts02Vette]

Yes vector can do it. I called and talked to them right before I got rid of the car. They said they could easily tune the tranny and shift points.

[todds87ss]

I wonder why some people want even more after they've had the camaro 3.45 in their A6.

I see more folks regretting the 3.45 in favor of the 3.27.
The change in HWY mileage and RPM is the main reason. With the A6 the 2.92 yields around 1800 rpm at 80 mph. with a 3.27 = about 2100 rpm (my estimate, but close enough for this exercise). with a 3.45 - about 2350 rpm (too much for my taste), and I have not done the numbers for the 3.70. gotta be in the neighborhood of 2600 rpm. I could not live with that on the HWY. My original thoughts were to go 3.45 with a taller tire to get back to the 3.27 range, and at the track, use the DRs to get my gear back. If I come across another 3.45 cheap - that's where I'm going.

[-Ray-]

I bought a 3.27 just for this reason.

[SpeedRacerX]

I wonder why some people want even more after they've had the camaro 3.45 in their A6.

You'll have some wishing they had more gear and some regretting they went too big.

No true. The GXP rear is identical to the GT other than the ring and pinion are shot peened in the GXP rear. The camaro rear is about 25-30% bigger in actual size and from my research has better internals. By no means am I saying that the camaro diff is unbreakable but it IS stronger than the G8 diff.

Correct. Shot peened R&Ps are the main difference between GXP and GT diff. Camaro differences as you noted.

I see more folks regretting the 3.45 in favor of the 3.27.
The change in HWY mileage and RPM is the main reason. With the A6 the 2.92 yields around 1800 rpm at 80 mph. with a 3.27 = about 2100 rpm (my estimate, but close enough for this exercise). with a 3.45 - about 2350 rpm (too much for my taste), and I have not done the numbers for the 3.70. gotta be in the neighborhood of 2600 rpm. I could not live with that on the HWY. My original thoughts were to go 3.45 with a taller tire to get back to the 3.27 range, and at the track, use the DRs to get my gear back. If I come across another 3.45 cheap - that's where I'm going.

Funny, did a TON of research and polling a year+ ago of over 15 owners of swapped diffs and NOT ONE SINGLE PERSON that went with a 3.70 regretted doing it. Some even wanted more. I'd bet those people weren't the "should I or shouldn't I" fence sitters.

For the folks on the fence, 3.45 Camaro diff might be the best of all worlds, especially IN LIGHT OF what the OP described as his driving scenario and wants out of the diff. He's not on long highway drives much to worry about the highway RPMs.

During my research I also compared the G8 GT to other 350-400+ HP sedans in the world with Auto transmissions and found that the first gear ratios times the rear gear of these other performance luxury sedans equated to somewhere BETWEEN a 3.45 and a 3.70 gear in the GT even with our steep first gear. It was actually closer to the 3.70 end of the average than the 3.45 end. We are NOT unique at all for a heavy, 4-door, auto, high hp car. In fact, we are undergeared compared to most, if not all, comparable cars.

What we ARE is very lucky and spoiled with what this car delivers out-of-the-box, for its price, in regards to power versus gas mileage and so sometimes we get hesitant to change a good formula and risk losing something....driveability, manners, gas mileage, sound, etc. But then again, isn't there usually some kind of tradeoff that comes with the modding turf?

End goal and related consequences should drive the mod decision.