dave1234

I have heard people say to get a large rear gear like 3.73 or 4.10 to go with the wide ratio T56, mainly due to the low .50 6th gear, otherwise the 6th is unusable. My question is doesn't that make the 1st gear virtually worthless 2.97x3.73= 11.07 or 2.97x4.10=12.1.
Isn't that too high compared to the magical 10 for 1st?
But if you go with a close ratio 1st gear for me would be 2.66x3.36=8.9 but the 6th gear is about where I want, 76mph at 2,000rpm on stock 27" tire
I have a 3.36 rear gear and am trying to figure which tranny to go with...
Seems like neither of the T56's are set up ideally. I love the set up I have in the 04 z06 but that tranny's cogs aren't offered aftermarket
Suggestions?
Please enlighten me

Gordonm

I am running an 06 GTO a T56. I run a 3.70 rear. 1st gear is as I recall 2.97 and 6th is a .62. This combo works about as well as any combo. I don't buy into the magical 10ish 1st gear ratio. I have run this setup behind a 383 with about 500 HP. Currently running it behind and Ls3 with a little over 500 HP.

cagotzmann

Your Z06 should have a 3:42 rear and wide ratio gear set

2.97:1
2.07:1
1.43:1
1.00:1
0.84:1
0.56:1

This compared to a 3:36 rear with the T56 gears in a blind test you would not be able to notice a difference.

If you are road racing / Drag racing then pick a ratio that works with the rpm / hp / torque curve of the engine.

For street driving you will not notice any difference.

74modified

It also depends on the torque range range of your engine. I use the .57 6th gear (TR6060) with a 3:55 rear and a injected LS with only ~300HP. I don't think it would be usable with a carbed SBC of the same power -or even a little more because the torque curve would not allow it to run well at that low a RPM. Even then I only use 6th above 60mph and run ~1500rpm @75

dave1234

LS1/MM6 T56 2.66, 1.78, 1.30, 1.00, 0.74, 0.50 seems geared for lower rpms

LS6/M12 T56 2.97, 2.07, 1.43, 1.00, 0.84, 0.56 seems geared for rpms

Aftermarket T56's:
Close T56 2.66, 1.78, 1.30, 1.00, 0.80, 0.63
Im worried with this I would want a 3.73 axle to get any acceleration instead of the 3.36 I have, but that I would be getting too many rpms in 6th to be useful
Wide T56 2.97, 2.10, 1.46, 1.00, 0.74, 0.50
Im thinking with my 3.36 axle, the first gear in this would be nice but as others have said you would have to hit crazy speed to be able to actually use 6th (80+mph)

It seems like Im noticing that the wide is reallyyy wide considering 1st and 6th.
For aftermarket I would like the 2.97 1st from wide ratio and the .63 6th from close ratio.
Who knows. Maybe you cant have it all

MIKE80

My T56 is out of a 94' Trans Am with 2.66, 1.78, 1.30, 1.00, .74, .50 and I use a 3.70 rear with 25.55" tires (275/40 ZR17). I use 5th gear on highways and 6th gear on the interstates. At about 65mph in 5th I'm at about 2450 rpm, and in 6th I'm at about 1650.

cv67

Believe the gearsets are available but pricy. when I had mine apart last yr I reeeealy wanted one but was cost prohibitive

6th is just for mpg and not pulling in these things;dont buy the 10:1 1st is the only way either moreso a general guide.

63mako

Close T56 2.66, 1.78, 1.30, 1.00, 0.80, 0.63 Got this with a 4.11.
10.93 to 1 overall first gear- 47 MPH @ Redline,
3.28 to 1 fifth gear- 2700 RPM @ 65 MPH
2.58 to 1 sixth gear- 2100 RPM @ 65 MPH - 2600 RPM @ 80 MPH.