im going to be using the stock c4 auto tranny, with a rebuild and better torque convertor, which gear ratio, im thinking 3.5?

 

also whats the difference between 28 spline and 31? and i've seen different differentials for sale like posi, open and detroit locker, whats that all about?

 

(1) If you're going with a "looser" torque converter than OE, you have less need for 3.5's, and will be spinning slightly higher revs while driving due to slightly higher slippage across the torque converter.

(2) Spline count is related to the diameter of the axle shafts. Higher spline count = larger OD = stronger (axle shaft material specs assumed equal for the two).

(3) The difference is in how well and under what conditions the differential will permit the two wheels to turn at different speeds (such as is required for turning tight corners). "Posi" wants to keep the wheels turning at the same speed until a preloaded friction assembly reaches some difference in wheel traction loading and slips. Open provides no resistance to one wheel spinning faster than the other under any circumstance (will usually spin the right rear wheel only on hard acceleration). Locker locks the two wheels solidly together under acceleration but unlocks on coast or deceleration (doesn't like tight turns under power). There's also atorque-sensing device(gear-driven limited slip device, aka Torsen, Quaife, Black Gold).

Lots more reading here.


Norm

 

there we go, thats what i needed, how differentials work, thanks buddy!