jon-d

I have a 96 grand that I should (need?) to install a SYE kit on. it has a 6" lift, so everything I read says I should have it installed. I also read that the only option for my transfer case (242) is a hack-and-tap, which apparently is not that strong. should I look to install a 231 transfer case?


the other thing...assuming the 242 is fine, I cannot find a SYE kit listed for a 242 at the places I have been looking. Anyone have one they can recommend?

dave1123

Okay, have you looked under your jeep to see if you actually need one? The reason I ask this is because my 97 with the 242 had a flange mounted driveshaft with the slip joint in the shaft itself so it didn't need a SYE.

Fred/N0AZZ

Tom Woods makes an SYE for that TC and a driveshaft.

jon-d

well Dave I don't know. a buddy of mine who is a mechanic and into jeeps tells me I need one. the shaft has a slip joint in it but I thought they all came that way. I am new to jeeps and picked this up a few weeks ago so I am going through it fixing the electrics and making it more off-road worthy. I don't want to be a burden on the other drivers when I do go out. I should take a photo of what I have and post it. I will do that when I get home tonight.


thanks Fred, I will look into Tom Woods.

jon-d

Fred, I found his web sight looks like $470 plus shipping - thanks!


so now I have some questions on the 242 vs 231 transfer cases before I dump money into this area of my jeep. I read up on them and it seems that the 231 is the better transfer case? also, correct me if I am wrong, but the 242 does not have the Viscous coupler, right? I really don't understand why one might be better than the other.

dave1123

The NP249 is constant 4wd with a viscous coupling to compensate for slippage between the front and rear shaft speeds when there is a difference, like for cornering. All it gives you is 4hi, neutral, 4lo.

NP231, usually found in Cherokees (XJ). it gives you 2wd, 4wd, neutral, 4lo, BUT 4wd is called part time because it should only be used on loose or slippery surfaces. There is no difference in the 2 shaft speeds.

NP242 has 2wd, 4wd part time, 4wd full time, neutral, and 4lo which is part time. It's the same as the 231 with the added feature of using it in full time 4wd which uses a differential type thing to replace the viscous coupling. The only problem with this is when in full time, if one wheel looses traction, it spins and you don't go anywhere. I proved this with my WJ. One wheel in ice and it just spins until it rolls off the ice, then it launches like NASA!

Some people say the 231 is the strongest of all jeep t/cases. It is pretty strong and is simple to fix. To answer your question about the viscous coupling, it's a sealed unit with a viscous fluid in it that allows the front and rear shafts to run at different speeds, turning the slippage into heat. If it gets too hot, it will burn out. It costs a BUNCH of bucks to replace and requires the complete disassembly of the case to fix. It's only used in the 249 t/case. In the 242, this slippage is accomplished with a planetary differential.

One mechanic told me the viscous coupling is like a torque converter filled with jelly!

jon-d

thanks Dave, your a wealth of knowledge. so for clarification the 242 locks in 4L for both the front and rear drive shafts? in other words its a real 4x4 that I can do some crawling with?

Cane

the difference is with the 4HI. on the 242 you have the option of going full time or part time. part time is what you described, both axles locked together, which is what the 231 also has. the difference is full time allows you to drive on pavement while being in 4x4, which the 231 can't do (it'll mess up your diff when turning)

i have no idea if one is stronger, but i love my 242. you can drive in 4x4 during the winter no matter the conditions without any chance of messing anything up. with the 231 you'd have engage/disengage the 4x4 each time you leave snow and get on pavement and vice versa. if you don't live where there is a lot of snow, it might not be appealing as much, but I really appreciate it up here. the only downside I know is that it's tricky to change gears and sometimes stays stuck and you have to wiggle it, give gas, coast, give gas again, and bam, it falls into gear. i heard it's a common "issue" with the 242, but lube the shift linkage properly or replace it and it'll be fine.

dave1123

Yes, it locks both axles together in 4hi part time as well. It's just 4hi full time that you can drive at any speed at any time. I've found full time makes it feel more stable in the rain or patchy snow.

jon-d

Thank you for the detailed explanation it really clears things up guys.

jon-d

Here is a photo of my drive shaft and case. Now that i thi k about it i am not sure how to tell if i have a 6" lift. I am gping off what the seller told me.

dave1123

Well, from the wear band on the sliding yoke, you can see where it used to run! AND yes, you need an SYE. The yoke isn't onto the splines by much anymore and will eventually cause vibration as it wears the splines.

Fred/N0AZZ

Yes that's quite a bit of it pulled out, its a wonder he didn't have problems with it before.

andrewmp6

Looks like not much is even holding it in anymore.

jon-d

ah geez fellas now i am scared to take it out of the driveway. slip yoke eliminator it is!!!