Rear gear swap?

[Last Ride]

Hey all--
I am wanting to go with a more aggressive rear gear in my car (a 3.08 right now). I currently have a 4L60E transmssion, but I will eventually be changing that; probably to a TH400/GV overdrive. What gears should I go with? I was thinking a 3.36 or maybe even a 3.55 for the 4L60E, but the gearing of the TH400/GV would be more suited with a 4.11. I don't do a lot of highway driving right now, but I want a decent cruiser when all is said and done. It was alos recommended to me by the shop that has been doing my work that I change the entire rear "pumpkin" as it would be cheaper than just swapping out gears. I had the entire rear axle including the pumpkin rebuilt about three years ago, so if I can save some money this time around, I would like to. Any thoughts?

 

[fasterthanu]

I have a 1976 vette. I had a 3.08 gear also. Go with a 4.11 with a 700R4 Trans. Talk about get up and go!! The 1st gear of a 700R4 trans I believe is 3.06 vs. the normal first gear of a TH400 of 2.48. That alone would make your 3.08 gear pull out of the hole like a 4.11 in first gear. With a 4.11 gear, it just gets up and goes. The beauty of it is that the 700R4 trans has a .8 OD so you will be taking the same in 4th gear as you are right now with your 3.08!

http://www.700r4.com/FAQ/ratiocmp.htm

 

[Doug78]

The 700R4 OD is .70:1.
The 4L60E has the same ratios as the 700R4 as it is simply an electronically controlled evolution of the same tranny.
700R4 = 4L60 = 4L60E

For those looking for a taller first gear the 4L80E has the same gears as a TH400 but with the addition of a .75:1 OD. The 4L80E is found a newer full pickups and SUVs.