How can I find out what gearing I have in my Samurai? I just recently bought it and I am new to the Samurai world. All I know is that the guy i got it from says it has a 1.6 16v w/msd ignition, a 5speed tracker transmission, stock Samurai transfer case. The rear end is locked full time but I'm not sure how. No idea what gears the diffs are. It's lacking power on the freeway so I am looking at transfer case gears but I'm not sure whether to get 4:16 or 4:9 gears. I have 31" tires on it now with a SPOA with stock springs. I have a set of 2" Bonzeye springs that im going to install as soon as my Hi Steer shows up. I don't plan on going over 33" in the future. I don't plan on doing any heavy duty rock climbing, mostly plan on using it for hunting and driving back and forth to work.

I would go with the 4:16 unless you like high rpm's going down the freeway!

How can I find out what gearing I have in my Samurai? ...  the guy ... says it has a 1.6 16v, a 5speed tracker transmission, stock Samurai transfer case. The rear end is locked full time but I'm not sure how. No idea what gears the diffs are. It's lacking power on the freeway so I am looking at transfer case gears but I'm not sure whether to get 4:16 or 4:9 gears. I have 31" tires on it now with a SPOA with stock springs. I have a set of 2" Bonzeye springs that im going to install as soon as my Hi Steer shows up. I don't plan on going over 33" in the future. I don't plan on doing any heavy duty rock climbing, mostly plan on using it for hunting and driving back and forth to work.

 
One way to look at gearing is to assume that the factory's engineers got gearing about right.  So you might add additional high-range reduction, percent-for-percent, for the additional tire size.  Factory Samurai tires are 207/70R15 which works out to about 26.3" diameter. Your 31's, assuming full height tires (most are NOT), work out to +18% diameter.  Transfer case gears are known by their LOW-range ratio, so you'll have to research the high-range reduction.  4.9:1 T-case gearsets commonly have 16-18% additional high-range reduction, depending on whose you buy.  The 4.16:1 gearsets have 12% high-range reduction.  

Another factor or two to consider is that the 1.6L makes its torque a bit lower in the RPM range (perhaps as much as 10%) , so you'll likely not need quite as much additional reduction.  Early Samurais has a higher (lower numerically, 0.795:1) 5th OD gear, which was later increased (to 0.865:1) giving abut 8-9% more RPM and torque, needed on the highway.  Your 1.6L may not need the additional reduction of the later Samurai 5th gear.  I cannot speak to Tracker transmission ratios.
        
If you change R&P gears, you'll need to change both front and rear.  Above ~31" tires, this is a useful and common change.  See: http://www.trailtough.com/index.php?view=article&catid=36:techinfo&id=60        

You can get a good idea of gear ratios by counting turns on input and output shafts.

Yep, if you follow Merlin93's advice it should put you back in the power range of the engine. 

I'm in a similar situation; getting larger tires with stock gearing everywhere on my Sami.  I'm going to 31.8" tire which will nessecitate about a 20% change in the T-case gears to bring my sami back to life.  For me, I have to go crazy and get the 6.4 or 6.5:1 gears.  That won't be a problem for me though, I go to Moab to visit relatives every year where the low range reduction will make things easier.

Rob

Great info. Thanks for the reply Merlin!