Ok, guys, I'm trying to put together an Excel spreadsheet that will show the effective gear/crawl ratios after tire size and gearing changes. Need someone to confirm some basic calculations to see if I'm on the right track.

Ok, assuming manual tranny JK Rubicon.

1st gear - 4.46

Axle ratio - 4.10

Final drive ratio = 18.3

1 - Now, if I change to 4.56 gears, the final drive ratio is now 20.3, right?

2 - What if I stay with the 4.10 gears and change to 35" tires... effective final drive ratio is 16.7, right, since the larger tires will effectively raise your final drive (which necessitates the need for gear reduction).

Let me know if those calcs are right and I think I'm on the right track.

 

You can verify your numbers here!!!

http://www.currieenterprises.com/ces...lculators.aspx

 

I posted this before:

I setup this excel spreadsheet so it can be used the see the gear changes we make in our JK's. There are 2 tabs in the spreadsheet, one for 6 speeds and one for autos.

You can select the final drive ratio, tire diameter, gear, and transfer case position for X and Rubi. You can compare your existing setup to any combination of new setup in any gear and see the RPM and Speed. It will also show you the % of mechanical increase or decrease the motor will see.

When you click on a cell that has a variable you can change, a drop down menu will show up for you to make a selection

 

PeeJ, I've got that one. The one I'm workin' on isn't quite as fancy (no graph), but it shows the gear/crawl ratio of all 6 gears with multiple low ranges at the same time.

 

Thanks, David, I'll check it out.

 

Nice job. I also have a spread sheet for that. I'll compare your numbers to mines to see if our calculations are the same.

 

I think the calcs look right. Lemme know if I screwed up anywhere.