I am curious as to what the differences and or advantages to the different types of T cases on XJ's Mine is a 99 with a np231, seems to be the one you want. My friend is looking at a 89 XJ with a 242, I hear its full time 4wd, does that mean hes going to get alot worse MPG? Is it a bad t case? Any info would be great thanks guys.
Differences in T cases on XJ
- Thread starter NoTrax
- Start date
From JU.
TRANSFER CASES
The transfer cases used are all chain driven with aluminum housings. NP stands for "New Process" which is the brand, if you will. The newer ones are NV instead which stands for "New Venture". It is the same transfer case just a different name.
NP207 - "Command-Trac" part-time only - 2.61:1 ratio low range - used 84-87
NP231 - "Command-Trac" part-time only - 2.72:1 ratio low range - shift pattern 2H - 4H - N - 4L - used 87-01
NP228/NP229 - "Selec-Trac" - 4Hi(full-time) - N - 4Lo (part-time) - used 84-87
NP242 - "Selec-Trac" part-time OR full-time - 2.72:1 ratio low range - shift pattern 2wd - 4part-time - 4full-time - N - 4LO - used 87-01
242 is not a full time 4wd t-case. I hope this helps.
TRANSFER CASES
The transfer cases used are all chain driven with aluminum housings. NP stands for "New Process" which is the brand, if you will. The newer ones are NV instead which stands for "New Venture". It is the same transfer case just a different name.
NP207 - "Command-Trac" part-time only - 2.61:1 ratio low range - used 84-87
NP231 - "Command-Trac" part-time only - 2.72:1 ratio low range - shift pattern 2H - 4H - N - 4L - used 87-01
NP228/NP229 - "Selec-Trac" - 4Hi(full-time) - N - 4Lo (part-time) - used 84-87
NP242 - "Selec-Trac" part-time OR full-time - 2.72:1 ratio low range - shift pattern 2wd - 4part-time - 4full-time - N - 4LO - used 87-01
242 is not a full time 4wd t-case. I hope this helps.
crimsonride
huh?
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- Murray
I'd have to say that the 4HI-Full Time is nice to have when here. Doesn't bind on the road so you can drive it when the roads have ice patches on them and such.
The 242 is full time selectable, meaning that you have the ability of full time 4wd if and when desired as well as 2wd AND ALSO the part time hi & low range of the 231. Think of it as a differential in your t-case; it allows the drivelines to operate in full time 4wd at different speeds for smoother performance around corners without the steering wheel "sawing" back at you like when in part time and the drivelines are locked together.
This is a great benefit for slick surfaces, rain, snow & ice. You can also use full time 4wd on dry surfaces without any adverse effect. Your gas mileage will not change that much at all since XJ's do not have disconnectable front hubs. This means the front driveline turns all the time anyways, so your mileage won't change much, if at all. Some earlier XJ's (pre 91) had an optional vacuum disconnect on the front axle but it was never packaged together with the 242 for obvious inability of "shift on the fly" reasons.
The strength difference between the 231 and 242 is not much at all considering how light weight the XJ is. The 231 is only slightly stronger. The ratings are listed on NVG/NPG's website.
I have 2 XJ's both with 242's because of the selectable full time advantage they offer. My overhead computer shows less than a 1/2 MPG difference between fulltime use vs 2wd use.
This is a great benefit for slick surfaces, rain, snow & ice. You can also use full time 4wd on dry surfaces without any adverse effect. Your gas mileage will not change that much at all since XJ's do not have disconnectable front hubs. This means the front driveline turns all the time anyways, so your mileage won't change much, if at all. Some earlier XJ's (pre 91) had an optional vacuum disconnect on the front axle but it was never packaged together with the 242 for obvious inability of "shift on the fly" reasons.
The strength difference between the 231 and 242 is not much at all considering how light weight the XJ is. The 231 is only slightly stronger. The ratings are listed on NVG/NPG's website.
I have 2 XJ's both with 242's because of the selectable full time advantage they offer. My overhead computer shows less than a 1/2 MPG difference between fulltime use vs 2wd use.