Markrobinson
Well-Known Member
- Joined
- Aug 13, 2010
- Messages
- 700
Long story short, I want to build my next rig as a capable street legal trail rig that can take me to work in a pinch or take the family to sonic on a hot July Friday night. It's gonna be an xterra (laugh it up fellas) 
I plan on using a stock tcase/np205 doubler, an automatic, and 37s.
I like stock based axles for cheap and plentiful 4.63 gears, but not for $450 5.13 gears.
Knowing that many ultra4 buggies are being built with overdrive autos and 2.0 or 3.0 transfercases often kept in low range through rock and speed sections (to avoid stopping to shift from low to high) I decided to hit up an RPM calculator.
With 4.63 axles and 1.96 transfercase, my effective single low range axle ratio would be 9.0478. Seems low, but at 70 MPH I'd only see 4500 RPM (assuming a .85 overdrive; I couldn't find that info anywhere). In reality, I doubt I'd ever hit 70 unless for the sole purpose of saying I could.
Keep in mind, I wouldn't be commuting in this rig, but I want to be able to park my tow rig and drive this to and from trails and perhaps into town on wheeling trips. More importantly, for places like Moab, this would be a necessity.
Anyone think this is a bad idea? To me it seems like a good way to put the gearing and heat burden somewhere other than a $1000 transmission, while retaining stronger and cheaper axle gears (and gears for which I can potentially carry a apart third).
I figure any Toyota guys with a doubler in a street legal rig could perhaps lend some insight. Last rig had a 22r and a single 4.7 case on the same axles and I felt it was too low half of the time and even in a samurai, would barely pull in high range.
I plan on using a stock tcase/np205 doubler, an automatic, and 37s.
I like stock based axles for cheap and plentiful 4.63 gears, but not for $450 5.13 gears.
Knowing that many ultra4 buggies are being built with overdrive autos and 2.0 or 3.0 transfercases often kept in low range through rock and speed sections (to avoid stopping to shift from low to high) I decided to hit up an RPM calculator.
With 4.63 axles and 1.96 transfercase, my effective single low range axle ratio would be 9.0478. Seems low, but at 70 MPH I'd only see 4500 RPM (assuming a .85 overdrive; I couldn't find that info anywhere). In reality, I doubt I'd ever hit 70 unless for the sole purpose of saying I could.
Keep in mind, I wouldn't be commuting in this rig, but I want to be able to park my tow rig and drive this to and from trails and perhaps into town on wheeling trips. More importantly, for places like Moab, this would be a necessity.
Anyone think this is a bad idea? To me it seems like a good way to put the gearing and heat burden somewhere other than a $1000 transmission, while retaining stronger and cheaper axle gears (and gears for which I can potentially carry a apart third).
I figure any Toyota guys with a doubler in a street legal rig could perhaps lend some insight. Last rig had a 22r and a single 4.7 case on the same axles and I felt it was too low half of the time and even in a samurai, would barely pull in high range.
