5.9 dd transfercase

[alteredxj]

ok so heres the deal i have a stock 5.9 i use for my dd i live in Vermont and my sales route has me on muddy job sites. i already have a built xj for off road so im keeping the 5.9 stock for now my question is i have a 242 tcase and both driveshafts out of a 98 4.0 grand, what would be the advantage of going to the 242 vrs the 249 i have now other than burnouts.

[Green Mountain ZJ]

Better mileage, less wear & tear on front end, and it is easier to turn tight corners (like when you are parking it). If you can live with that don't worry about it.

You have the newer version of the 249 that locks the front and rear axles in in 4low. The earlier versions allowed the front and rear axles to turn at different rates. It becomes a problem when you have one wheel in the air. The newer version still does this in 4hi but it is advantageous with AWD. Hope that helps.

[Casey L]

If your 249 is in good condition keep it. I loved mine in New England snowy roads. A viscous coupler limited slip for a center differential is a very efficient setup. The same setup is used in luxury AWD cars.

However my 249 is junk now, and 231/242's are much cheaper than a $500 viscous coupler.

[J B]

Better mileage, less wear & tear on front end,

Nope and nope. He can run the 242 in 4FT and it will have the same wear on the front end and mileage as the 249.

All of the parts still spin (even if you had it in 2WD), so no reduced wear or better mileage.

The 242 has the advantage of having a 50/50 torque split, instead of the late 249's 90/10 split in high range.

But, the 242 has an open center diff in 4FT, whereas the 249 has a viscous coupling that will send at least some power to the axle with traction.

So, there are plusses and minuses to both scenarios. Personally, I'd go with the 242. It has low lock as well, so if you needed locked 50/50 split, you could get it in a pinch....and you'd have 50/50 open split the rest of the time.

[Sporer65]

I would keep the 242 until the 249's VC goes, then swap. That way you can get the most out of the 249 and not get rid of a good transfer case. Then when you have 242, you can keep 4FT for those snowy situations.

[J B]

If you have the 242, might as well keep it in 4FT. No reason to use anything but 4FT and 4LO.

[alteredxj]

thanks for all the info it is a big help i will keep the 249 untill it causes a problem the 242 is safely tucked away in storage until needed.

i dint think it would change the milage as you are still turning all the same componets even when in two wheel. also if i try to lanch it it will not hook as well in two wheel

[Green Mountain ZJ]

Nope and nope. He can run the 242 in 4FT and it will have the same wear on the front end and mileage as the 249.

All of the parts still spin (even if you had it in 2WD), so no reduced wear or better mileage.

It WILL actually get better mileage. This is because there is less resistance. When you are turning corners and the wheels are turning at different rates there will inevitably be some kind of bind. This is the reason for the viscous coupler and although it makes driving in 4wd more acceptable it does have the resistance. In 2wd the parts will still be turning but with less resistance. Better mileage and less wear and tear result.

[J B]

It WILL actually get better mileage. This is because there is less resistance. When you are turning corners and the wheels are turning at different rates there will inevitably be some kind of bind. This is the reason for the viscous coupler and although it makes driving in 4wd more acceptable it does have the resistance. In 2wd the parts will still be turning but with less resistance. Better mileage and less wear and tear result.

No. Your theory is sound, but in practical terms, that's not what happens. Only if the VC in the 249 is toast and locked up will it possibly make a difference. The VC transfers more torque based on the difference in speed between the front and rear driveshafts. When you turn, there is some speed difference, but it's very little. The difference is more the sharper you turn. Being that driving around doesn't require the type of tight turns you'll see in parking lots, etc. you'll not see a noticeable difference at all.

In 2WD, there's no less resistance, and all of the same parts are turning. A buddy of mine had a '93 ZJ and tested this exact theory. Watched his mileage closely for the last several hundred miles on the 249, and then installed the 242, stuck it in 2WD, and monitored it for the next several hundred miles. ZERO change in his gas mileage. On top of that, the VC in his 249 was locked up soild for all those miles.

The only advantage to having the VC is the fact that it will allow seamless daily driving, while still being able to transfer some torque to the axle with traction. With a 242 in 4FT, one tire off in the mud, and you're stuck. All of the power will be routed through all of those open diffs to the tire with the least traction.

That's what I don't like about the late 249...the 90/10 torque split means that you basically have to lose traction on the rear before any significant power gets sent to the front.

If the early 249 with the 50/50 split had low lock, it would be the ultimate transfer case to have in a street driven, but sometimes offroaded vehicle (just speaking from a function standpoint here, not a strength standpoint).

The 242 has advantages, but better fuel economy is not one of them. Now, if you had locking hubs up front and could actually disconnect some rotating parts, then you'd be getting somewhere.

[wonder371]

cue ball has a nice Transfercase for sale, i think. (I think its a 242HD w/ a tom woods sye)

[jsteves]

If you have the 242, might as well keep it in 4FT. No reason to use anything but 4FT and 4LO.

What the hell sense does that make? Put it in 2 wheel drive unless 4 is needed, then he would have all options.

In slick ice and snow the 96-98 249 does very well. I would leave it in until it is burned up (My old man got about 120k out his 5.9 249).

[J B]

What the hell sense does that make? Put it in 2 wheel drive unless 4 is needed, then he would have all options.

In slick ice and snow the 96-98 249 does very well. I would leave it in until it is burned up (My old man got about 120k out his 5.9 249).

It makes all kinds of sense. You're driving all 4 wheels, even if it's in 2WD. You're just driving them through the road instead of through a driveshaft. Might as well get the benefit (4WD) since you're going to pay the price anyway (reduced mileage and increased wear on components).

[piku303]

That's what I don't like about the late 249...the 90/10 torque split means that you basically have to lose traction on the rear before any significant power gets sent to the front.

If the early 249 with the 50/50 split had low lock, it would be the ultimate transfer case to have in a street driven, but sometimes offroaded vehicle (just speaking from a function standpoint here, not a strength standpoint).

the early(93-95) 249 doesnt have low lock. the later one does(96-98).

[J B]

the early(93-95) 249 doesnt have low lock. the later one does(96-98).

I know that. Reread my posts.

[jsteves]

It makes all kinds of sense. You're driving all 4 wheels, even if it's in 2WD. You're just driving them through the road instead of through a driveshaft. Might as well get the benefit (4WD) since you're going to pay the price anyway (reduced mileage and increased wear on components).

yeah and put a lien on my house while you are at it.

[J B]

yeah and put a lien on my house while you are at it.

If you're stupid enough to sign the paperwork to allow it, I will.

[jsteves]

Have you ever drive a Jeep with 242? It is not nearly as good of onroad performer as the 249. It binds the front, skids the tires and is just all around kind of an annoyance. There is nothing to be gained by using it all the time. It is great to have for the slick months of the year because the binding, etc. is hardly noticable on slick surfaces and even if it was a small price to pay. But the rest of the year it kind of sucks on road.

[J B]

Have you ever drive a Jeep with 242? It is not nearly as good of onroad performer as the 249. It binds the front, skids the tires and is just all around kind of an annoyance. There is nothing to be gained by using it all the time. It is great to have for the slick months of the year because the binding, etc. is hardly noticable on slick surfaces and even if it was a small price to pay. But the rest of the year it kind of sucks on road.

Yes, I have and if it's in 4FT, then it's unnoticable. Perhaps you were driving it around in 4PT? Because that's exactly what you're describing. There's a reason they call it 4 FULL TIME. There's an open center diff in the 242 when in 4FT, and you should experience no binding.

If you do, then you're either not in 4FT, or that Tcase has an issue. End of story.

And for on road, I'd take the 242 any day over the late 249. With the late 249, you're basically in 2WD all the time, unless you seriously break traction on the rear so that you can send power to the front.....which means that you shift from basically RWD to FWD. Not that great.

[alteredxj]

well i can see no advantage of changing the tcase at this time it works perfictly and i agree that the gas milage wont change. most of my driving is highway as for off road i will use my xj. http://i179.photobucket.com/albums/w...Picture250.jpg i buoght the 5.9 to use at work get me to job sites and run in the snow. its way better than the ford exploder they offered me. and im saving miles on my 06 silverado

[Sporer65]

the early(93-95) 249 doesnt have low lock. the later one does(96-98).

That is why he said "If."

[jsteves]

Yes, I have and if it's in 4FT, then it's unnoticable. Perhaps you were driving it around in 4PT? Because that's exactly what you're describing. There's a reason they call it 4 FULL TIME. There's an open center diff in the 242 when in 4FT, and you should experience no binding.

If you do, then you're either not in 4FT, or that Tcase has an issue. End of story.

And for on road, I'd take the 242 any day over the late 249. With the late 249, you're basically in 2WD all the time, unless you seriously break traction on the rear so that you can send power to the front.....which means that you shift from basically RWD to FWD. Not that great.

You are an idiot. Trust me, I don't need you to explain full time and part time to me. I am fully aware of how the each of the t-cases works. If it makes you feel all warm, fuzzy, and gay inside then that is fine with me. Go spend some time on a trail instead of driving around the roads with your Jeep in 4 wheel drive to validate owning it.

[Green Mountain ZJ]

If you're stupid enough to sign the paperwork to allow it, I will.

Every time you post, I keep looking under your avatar where it says your post count and rep power. Thanks for helping me to understand why the mods put that there.

[J B]

Every time you post, I keep looking under your avatar where it says your post count and rep power. Thanks for helping me to understand why the mods put that there.

If you base your opinion on people's posts by their rep power, then you're an idiot.

[Green Mountain ZJ]

If you base your opinion on people's posts by their rep power, then you're an idiot.

It may not be a good indicator in all cases, but 550+ posts and no reps. You are either a post whore or full of shit. Maybe both.

[redline61]

In my old XJ with a 242, while in full time I could never feel any jerking or roughness. Even cranked one way I still couldn't feel it. I did like having the full time for the winter so I could just leave it and forget it. Either way I would just keep the NP249 until something goes wrong. Good luck.