Major differences between the np231 and the np242
- -The difference in horsepower is 22, with 265hp in the np231 and 243hp in the np242.
- The 3.4L engine is lighter, more fuel-efficient, and has a smaller turning radius than its 4.6L counterpart.
- Speeds up to 145 km/h are possible with an automatic transmission on both models; the manual transmission can reach 190 km/h on the 4×4 version of each model.
- The NP232 has a higher payload capacity at 3 tons, which is 2 tons more than that of the NP242.
- The NP231 is the only version that has external locking hubs.
- The NP231 is lighter by 150 pounds than the np242.
- The NP232 has a higher rpm maximum at 6,800 rpm while the np242 stops at 6,250 rpm.
- The np242 has more 2nd and 3rd gear ratio options for a lower gear range but it costs more than the np231. The 4×4 four-speed np231 and 4×2 four-speed np232 share the same valve body and input shaft with minor changes to each.
Which transfer case is better 231 or 242?
The NP231 and 242 transfer cases are very different with 231 being a part-time transfer case while the 242 is full-time. The 242 is better suited for trail riding and hauling a load due to it being full-time.
The 231, however, has more low-range gear options than the 242 but lacks low-end torque compared to the 242, which is better suited for going uphill or pulling a trailer. The 231 does have external locking hubs which come in handy when you get stuck.
Are all NP231 transfer cases the same?
No, there are nine different versions of the NP231 transfer cases. The five different serial number prefixes and four different part numbers were created to keep track of the different variations made on each transfer case. The part numbers are located on a sticker inside the transfer case.
Each version is designated with a letter that is placed after the serial number. There are nine versions of the NP231 transfer cases: NP231, NP231A, NP231B, 231C, 231D, 231E, 231F, 231G and 231H. Here’s how to tell them apart.
NP231 is from 1983 through 1989 = no locking hub provision and no low range gear reduction option (3.91:1) NP231A is from 1990 through 1994 = has internal locking hubs and a 3.91:1 low range gear reduction (PN 80073-C1).
The 231C started production in mid-1994 and was built through 2000 with external locking hubs and a 2.72:1 low range gear reduction (PN 3593789) and an optional 3.42:1 low range option (PN 80073-B2 or PN 3593792).
Then a factory overdrive was added as an option to the 231C at the end of 2000 (PN 3593829). This combination of options became the standard for the NP231C starting in 2001. External locking hubs and a 2.
How much power can an NP231 handle?
The 231 can be swapped into most of the Jeeps that came with a 242 – it’s lighter and has less torque multiplication so there is less stress on components – and can handle up to 265 hp in a 4×4.
The 231 can handle more power than the 242 transfer case, but should never be used if you’re running more than 250 hp. Plan on using an upgraded driveshaft if you install a 231 in a Jeep with larger tires than stock, due to its lower gearing.
What kind of oil goes in a NP231 transfer case? The NP231 requires 68w90 gear oil in the rear and 75w140 in the front.
Will a 231 fit my YJ?
If it came with a 242, yes. Earlier models of the 231 will not fit in with out changing the mounting brackets but if you get one from a 92+ wrangler or an XJ it should be a direct swap for most people.
Which transfer case is better internal v external lock?
External locking hubs are useful when trying to get unstuck for pulling trailers on loose terrain or for general maintenance purposes.
The external locking hubs are more reliable than the internal locking hubs but tend to engage at speeds of 5 mph and higher. This can be a disadvantage when trying to get unstuck in deep mud or snow.
The internal hubs tend to engage at speeds of 1-2 mph, which is a disadvantage when trying to get stuck. External lockers are best used on vehicles with automatic transmissions due to the fact that there is no chance of damaging the transmission if the vehicle gets stuck in gear.
Internal locks are best suited for manual transmissions because if you try using an internal locker on an automatic transmission, you will damage it while shifting gears as well as breaking axles from lack of lubrication and heat buildup.
