FJ40 axles w/ 38” tires under my Non-Yota

[ASI H8]

What I have – 1987 Suzuki Samurai, 1.6L 16v, Stock Samurai Trans, 6.5 Transfer case. Curb weight is a touch over 2000 lbs. Loaded up ready for the trails, myself included, it weighs out to 2440 lbs.
The next step/upgrade – 1978/9 FJ40 Land Cruiser axles and 38” tires.
After crunching numbers using http://www.lepayne.com/gears.html I will need to lower my R&P, but by how much? Stock FJ40 axles have a 4.1 ratio. Ratios I’m considering are 4.88 and 5.29. I’ve included where the rig is now, and the effects of larger tires/lower (4.1, 4.88, 5.29) R&P.

As it sits now - 3.73 R&P, 30” tires, 4% gear reduction on high side, 149% reduction on the low side. Low craw ratio is 88.47:1
4.1 R&P, 38” tires, 10% gear increase on high side, 116% reduction on the low side. Low craw ratio is 97.33:1
4.88 R&P, 38” tires, 8% gear reduction on high side, 157% reduction on the low side. Low craw ratio is 115.84:1
5.29 R&P, 38” tires, 17% gear reduction on high side, 179% reduction on the low side. Low craw ratio is 125.57:1

I have additional comparisons in the areas of gearing and MPH range for each gear of the transmission to Stock Samurai in a .jpg format. I’m having issues posting them for some reason. I can provide if needed.

Once I figure out (with your assistance) the R&P that will fit my need, I’ll be pimping ya’ll for suggestions on R&P manufacturer and source for purchase.

Thanks
Rob

 

[kc_chevota]

By my calc going from a 30 to a 38 would be a 26% increase in diameter. so if you want to retain drive train ratio your best bet would be the 5.29

 

[ASI H8]

From what I can tell the 4.88s would put me about where I am at now. I've had others make the point that 38" tires would be to hard on my transmission and to stay with the 4.1 so it would keep me out of 5th gear. Also 4.1 R&Ps are easy to pickup.

 

[ASI H8]

After doing some additional math, I think I'm dropping the R&P to 5.29. I have additional questions before I do:
1. Should I look for used or just go new?
2. If new, what manufacture should I go with?
3. If going the used route, does anyone have a set, front and rear?

 

[mandinga]

Real quick side note. I ran into a turbo diesel Sami the other day it was completely stock and the owner wouldn't entertain any offers. I wasn't aware there were diesel sami's here in the US. I've been looking online for another. Did they offer the diesel option here in the states? This little rig is bad ass.

 

[ASI H8]

Real quick side note. I ran into a turbo diesel Sami the other day it was completely stock and the owner wouldn't entertain any offers. I wasn't aware there were diesel sami's here in the US. I've been looking online for another. Did they offer the diesel option here in the states? This little rig is bad ass.

Completely stock turbo diesel Samurai? Shipped to the US, no. Somewhere in the world, yes. Alot are doing VW TDI swaps. I know of one in the KC area. Was it a grey/silver Tin Top on a 2-3" lift? If so the engine is VW.