98', 242,30/ 8.25, first lift on it was 3.5 ", vibes were so bad i pulled the rear driveshaft off and drove it in front wheel drive until i soon did the hack & tap w/ a new cv driveshaft. like magic it was as smooth as a stock xj. used the hack & tap for 4 yrs w/ no problems at all until i recently installed a tj ruby 241.

 

I have a SYE but have not installed it yet. I had pretty good vibes with a 3.5 in. lift that netted me 4 to 5 in. in the back at first that has settled a lot and very minimal vibes now. My suggestion would be to load the back up with as much weight as you can for a while, it will settle. What helped me is that mine is not a DD. I’m still going with the SYE but not until I do the no lift shackle boxes and I guess new shackles. Which is another suggestion I have is go with less lift than you want in the back then do shackle relocators, just sayin.

 

 

1996 auto np242 c8.25 3" lift stock rear shaft needed t case drop.

This lift went in with new u joints and had vibrations on acceleration and deceleration unless it was full of gas and tools. T case drop cured the vibe. I did not measure the actual lift amount when new (2012?) but I think it has settled and I could remove the drop.


1989 auto np231 d35 6.5" lift stock rear driveshaft with t case drop. Worked fine. No vibes.
Actual lift measures 8" over stock

Changed to manual, np231 with sye, ford 8.8 rear and used 33" collapsed length front driveshaft from 1980 chev 1/2 ton.

 

'88 3.5" lift with a swapped c8.25 rear and HP30 front. Just running the Rusty's HD crossmember that gives a 1" drop over stock while maintaining stock clearance. I have a SYE Tcase sitting for when I do swap over but no vibes as is.

 

Later models (97 and up) tend to have vibrations at smaller heights compared to other models. My 99 had vibes with a 2.5 inch lift until i dropped everything back to 2 inches.

 

I used this hack an tap and it uses a stock front drive shaft . https://www.ironrockoffroad.com/prod...nator-kit.html
It is simple to install it only took me about 3 hours and that includes a few beers .
I have a 4.5" lift . so now my xj uses the same drive shaft front and rear .

 

 

PORC SYE from Amazon and front XJ shaft, ~$200 total. Took me 3-4 hours to install with basic tools. Where are you getting $750?!

I'm at 5" of lift w/ 8.8 rear axle. No vibs. I did the lift, SYE, and rear axle all at the same time. No clue if it would have been ok without the SYE.

 

 

h & t from iron rock offroad, get the guide for centering the hole to be drilled. drive shaft was custom built from a drivetrain shop in baltimore. but lots of places out there to get the driveshaft built.

 

1994 ZJ 4.0 4" lift 242 no SYE and 33s. Minor vibes but I can just barely feel it.

 

1999 Cherokee Sport, 4.0L I6
NP231 transfer case
C8.25 rear axle
G2 SYE
3" Rough Country lift w/ new full spring packs

The SYE did not solve my vibrations. It in fact made them worse in my estimation. Vibs are not good. I'm sure my bearings are taking a beating. It sounds like a lawn mower at highway speeds.

Some looking at it revealed that the rear pinion is 7 degrees off from the transfer case output. No good, that needs to be zero. I considered shims, but at that big of an angle, the shock mounts will bind/break. Also not good.

At the beginning of April I'm having a local off-road shop re-weld the spring perches and shock mounts to correctly point the rear pinion at the transfer case. I already have the parts. The labor will cost me around $350-$400 (I'm pretty awful at welding, otherwise I'd do it myself.) I am taking this opportunity to install high-clearance shock mounts (link). If I have to get new ones anyway, I might as well raise them. Putting in beefier spring perches too. Again, might as well.


-T.

 

How attached are you to the 242? You can pull a 231 at Pick n Pull for $139.99, PORC SYE on Amazon $175, and XJ front shaft $35 (for rear).

Buy TC, do SYE and any other maintenance items while you have it on the bench. Then swap it for the 242. I understand the 242s command a decent price used, so you should be able to recoup a fair amount of your investment.