factory gear ratios and discussion on 3.23 final gear ratio

[olason]

Hello,

I am looking for a place to find the factory gear ratios of transmissions. I can't seem to find any talking about the base C6 corvette Tr6060 transmission ratios.

Also I am wondering on input on a 3.23 differential gear ratio. This is what is common in some AWD applications on every day cars. I know I could pick up an almost knew front Diff with these gears for about the same as a used astro, scylone, typhoon, awd bravada front differential even though the syclones had better gearing in them. Any input on how this would affect my performance if I went with this. this is just planning a build right now.

[JEFFTATE]

Found some good info at Corvette Action Center .

The Factory Corvette 6 speed transmission is available in two types .
http://www.corvetteactioncenter.com/specs/c6/2008/2008tr6060.html

[Motorcitydak]

6th gear (0.50) is going to be about useless for me. 6th at 90mph will be about 2000rpm. I think the other gears will be all decent tho yet still have good mpg with a 25 inch tall tire

[JEFFTATE]

Most of the factory Vettes use a 3.42 ratio.
And this works good on a car with a moderate cam .
A 3.23 is a little off to be used with the 1st gear or the 6th gear in a TR6060 ..

[olason]

Alright, well I found out that the astro vans awd front differential is available in 3.73 and 3.42 ratios. Checking to see what the rear differential I am using, 8.8" ford cobra irs, is capable of in gearing the 3.73 matches up. I am going to see if I can pickup one locally. I have the NV 146 transfer case and TR6060 getting shipped to me now.

[JEFFTATE]

Cool

[Motorcitydak]

As its been said, with a 6 speed you have 1 gear that you cannot use. Either you gear low and first gear hits red line at 15mph (not the actual figure) or 6th gear is so steep that you are never going fast enough to use it. I decided to let my 1st gear be usable and just not put it in 6th

Im sure you have been doing all this math as well, here is what I figure for my car. Circumference of a 25 inch tire is 78.5 inches. I figure ill shift at 6-6,500rpm. Lets say 6000 for rite now. The ratio's of my T-56 go like this 2.66:1, 1.78:1, 1.30:1, 1.00:1, 0.74:1, 0.50:1. My final drive of 3.23 as well.

Axle shaft rpm/tire speed @6000 engine rpm in each gear
1st 698rpm/51mph
2nd 1043rpm/77.5 mph
3rd 1428/106mph
4th 1857rpm/138mph
5th 2510rpm/186mph
6th 3715rpm/276mph (lol)

and at 75mph, 5th gear will be 2485rpm. 6th will be 1679 which is more than likely not fast enough to make it worth it. I pretty much bought the Viper T-56 because it is a strong, available stock manual transmission. I did not really care that it was a double over drive 6 speed.

From the way it looks with my figures there, you would be fine with a 3.42 or 3.73 gear. For example, 3.73 at 6000rpm for me would be 604rpm at the axle shaft or 44.9mph in first. 6th gear at 6000rpm is 3217rpm and 237mph. 75mph for 5th is 2784, 6th is 1881