Originally Posted by Xtremjeepn
I have 5:13 and the auto on 35s and almost wish I had gone deeper. The OD on the auto is 0.69 which is WAY too deep for the motor.
The 6 speed manual does not have as deep of an OD (0.84 vs the auto 0.69)and also has 2 more gears before the OD.
At highway speeds an auto with 5:13/35s is only turning 142rpm LESS than as STOCK Rubi 6 speed (4:10/32s)
Here is the math.
Auto with 35s and 5:13 at 65mph =2209 rpm in OD.
Stock 6 speed with 32s and 4:10 at 65 =2351 in OD.
A stock Rubi auto turns 1931rpm at 65mph which is WAY WAY too low for the motor to spin and have any power. This is why the auto is always coming out of OD on the higway. The 3.8L is just not turing enough power at that RPM. That is nearly 400rpm less than the stick stock!!!
You forgot a couple, for perspective.
42RLE auto with 32s and 3.21 (stock) at 65mph = 1512 rpm in OD
42RLE auto with 32s and 3.73 (stock) at 65mph = 1757 rpm in OD.
So, the 42RLE auto with 5.13s and 35s gives us an increase of 500-700 rpm over the stock setup of most models. You quoting the Rubicon gearing with a manual trans just muddied the waters even more.
I would like to retain the ability to just turn off OD when I need
to, rather than throw all fuel economy out the window by cranking 3K+ rpm at 65 mph.