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T case lowering kit vs SYE

N

northern jeepin'

NAXJA Forum User
Location
Quebec
I'm looking into buying a 4.5 lift kit for my 98 xj. Some brand say that you need a SYE others offers a tcase lowering kit. I don't really want to buy a expensive SYE and cv drive shaft. Would the vibration will be acceptable with t case kit?
 
I have a 4.5 RC lift and i wish i would have gotten the sye at the same time.

The t-case lowering kit is nothing more than some poly spacers with metal inserts. when you lower the case you are actually not lowering it as much as you are changing the angle of the whole drive train. and when you do this you actually make your front drive shaft angle worse esspecially with a lift. this causes vibes in the front end as well as can contribute to the dreaded death wobble.

you can make an sye by doing the hack and tap method do some searches on this site and im sure you will find a write up on it
 
I had my RE 4.5 kit on and had a TC drop and some angle shims, it was drivable little vibes nothing big. But I eventually got an SYE and MAN what a difference, I recommend one it drives aloot better.
 
idk what you guys did wrong, but i have a 4" custom lift and i lowered my TC an inch and a quarter and my drive lines went back to almost stock placement... then i pulled up my carpet and lowered the body side transfercase lever mount 3/4"... my very mild drive line vibes dissappeared. and my level works just like it did stock... dont get me wrong im sure a SYE will work better but my t/c drop worked as expected, and was a super cheap mod... the 1x2 tubing was free, drilled the hole's, think i paid 2 dollars for bolts, and .75 cents for rubber plugs to plug up the old holes after i drilled new ones in the body.
 
The correct answer is, it depends. No two Jeeps react the same to a lift...even more so for the last generation XJ's (97+). These are particularly prone to vibes due to a design change in the output shaft portion of the transfer case.

As for if you're going to need an SYE or not, probably. The only way to determine this is to lift the Jeep, then drive it and see what it does. If the vibes are minimal, then a 1" tcase drop will probably suffice....however the higher up you go the greater the chances of needing an SYE get.

It may seem like a lot of money, but in the end it's totally worth it. What transfer case do you have? If it's a NP231 (without the full time feature) then you have several options for a reasonably priced SYE.
 
Indeed different with every jeep. I lifted my 87 8 inches and dropped the t case 1 1/4 and had zero vibe. I did go through quite a few seals though on the output shaft! I'm doing the homebrew sye that is a sticky in this forum. I strongly suggest doing it. Its only around another 100 dollars.
 
i've check it out for the homemade sye and the instructions and yokes are for a 231. does it means the 242 have the same output shaft than the 231 ? I have a 87 xj pionner can i use the front drive shaft out of it?
 
I have a np242 in my 98 but an old 231 in the 87 ( which is just good for pieces now!) would it be better to simply swap it? it have 275 000 km on it but was still running fine
 
northern jeepin' said:
I have a np242 in my 98 but an old 231 in the 87 ( which is just good for pieces now!) would it be better to simply swap it? it have 275 000 km on it but was still running fine
Click to expand...

If i'm not mistaken, the spline counts are different between the years, so I don't think a direct swap will work. I could be wrong however.

Since you have a NP242, you have about two options for a SYE. The Rubicon Express Hack n Tap, which runs approx $200 in the end, or a Tom Woods set up, which is a heck of a lot more. I have the Hack n Tap set up on my Jeep (I have a 242) and I just helped a buddy of mine last night do one to his NP231...very easy to do, and you can use a driveshaft from any automatic 4.0 XJ (Doesn't matter the year)...which makes finding a driveshaft easy and pretty cheap from the junkyard.
 
cool, thanks for the info guys, i'll try to do the hack and tap. It's a pain in the ass to get parts and peoples who knows xj's here in eastern qc! most of the people don't even know what xj mean !!!!!!!!!!!!!
 
I never understood tcase drops. You lift your Jeep to gain some clearance and your just going to negate that by dropping your transfer case down???

Spend the money and do an SYE....
 
i guess that you could say that thats the "concept"? of lifting anything. but not everyone has the money right away to do certain things to their vehicle like you do.
 
MaxxXJ said:
i guess that you could say that thats the "concept"? of lifting anything. but not everyone has the money right away to do certain things to their vehicle like you do.
Click to expand...

True. Which is why many, including myself, install a tcase drop to help ease the vibes and buy some time to save money for an SYE.
 
UNCC_99XJ said:
True. Which is why many, including myself, install a tcase drop to help ease the vibes and buy some time to save money for an SYE.
Click to expand...

X2
In most cases a T case drop will work or get you by till you have thee money for a SYE. SYE is much better then a T case drop 99% of the time they are just kinda pricey so most people wait.
 
Weird I have an RE 4.5 lift and I have no driveline vibes at all. Im going to 6.5 inches soon and then I am going to start thinking about an SYE. To the OP, did you experience driveline vibes with your RC 4.5 lift or is that just what the company said?
 
i waited untill my AAL'd rear leaf pack destroyed my rear driveline u-joints, that way i wasnt replacing a good driveshaft.

im glad i did, i couldve gotten 2 more days outta that driveshaft! i still had grease in there, but thats it, no bearings. QUITE clunky...
 
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