Preliminary 2012 Pentastar Gear Chart (beta)
 

Here's an updated gear chart for the new transmissions and Pentastar. It's probably not perfect, but most things measured by gut an feel aren't. There is definitely some math involved, a collection of dyno charts and knowledge of how things change with bigger meats. By no means is it perfect and I'll wait for some feedback before I push any further ahead.

Based on 70mph and the same criteria as the chart I did for the FAQ.


http://farm7.staticflickr.com/6034/6...50dd30d1_b.jpg

What mph is the rpm based on? I'm assuming that's what this is in reference to.

Great job by the way! :beer:

He said 70 mph

Sorry I missed that. 70mph and aligned with the old chart data in the FAQ.

Extremely busy with work stuff, so I don't have as much time to spend on this as I'd like. When complete and after some editing based on some feedback it will look the same as the charts currently in the FAQ I did a few years ago.

As an aside, I am stoked about the new automatic transmission. In my opinion it has seriously cramped some of the advantages I see in a manual transmission. Moving the OD ratio the wrong way on the manual eats up half the slip when the converter isn't locked up on the automatic.

I actually edited that in.

Totally missed it. :doh:

That seems very accurate I have 34s with the 3.21 gears and the 5 speed auto. Cruising at 65 mph I am about 1700-1800 rpm and got on average 20 mpg. I may change the gears when I throw lockers in. Im debating 3.73 and 4.10.

I figured 70mph was what it was based on. Thanks for the quick update. I, personally, have been pushed to my limits of how bad I hate the gearing/tuning in my 08 auto. So much so, that I have almosted traded it twice for a manual. I have not allowed myself to go test drive a '12 yet. I know the outcome if I do. Seeing this make me feel very good about sticking with an auto. Although I really miss driving a manual transmission. My girlfriend has very little experience with one and she loves to take my current JK cruising. This may be the info I need to just stick with the auto. thanks again!

HUUH ?? :thinking: Care to elaborate in simpler terms please ?

Looks good. I know with my 4.10s, Auto, & Rubi tires, I run just over an indicated 2,600 rpm at 70 mph.

Wow! Huge improvement over the gear choices in the older JK's.