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99 cherokee, 6.5" lift question

T

The Badness

NAXJA Forum User
Location
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I have a 99 cherokee 4wd of course, I have the rough country 6.5 inch short arm lift that i am about install. I have a question though, How important is a SYE kit at this height? I'm on a bit of a budget, I dont do any crazy stuff with my jeep, just trail riding, do i really need one?
 
well on a 1996 or newer you almost always need one... you can shim the rear axle to tip the pinion up and drop the tcase 1"

BUT I doubt it will work. in fact I will bet you a beer that it will NOT work

if your truck was a 1995 or older, maybe...
 
LOL. Well, what's best and what's necessary aren't always the same. Here's what I'm running: 98 Cherokee, 6.5" lift, 6 degree shims on rear D44 axle, AX15, 231J with 1" drop (plus the thickness of the front control arm drop bracket braces), and stock rear drive shaft. There is some driveline vibration under heavy acceleration but not enough to be a problem in 6000 miles or so of use including Death Valley and Central Oregon back country travel plus some 75mph highway travel.

So, it can be done if you are fortuneate. Meanwhile, there is a 231J crawlbox in the works with a supershort SYE on the transfer case and rear driveshaft with CV joint. When it goes in the TC drop will be removed.

Good luck.
 
The Badness said:
I have a 99 cherokee 4wd of course, I have the rough country 6.5 inch short arm lift that i am about install. I have a question though, How important is a SYE kit at this height? I'm on a bit of a budget, I dont do any crazy stuff with my jeep, just trail riding, do i really need one?
Click to expand...


MANDATORY!!!!!!! Also for the sake of your kidneys I would get controol arm drop brackets.
 
The Badness said:
I have a 99 cherokee 4wd of course, I have the rough country 6.5 inch short arm lift that i am about install. I have a question though, How important is a SYE kit at this height? I'm on a bit of a budget, I dont do any crazy stuff with my jeep, just trail riding, do i really need one?
Click to expand...

It is very important to do it.

If you just drop the t-case an inch plus the thickness of the drop bracket braces and shim your rear, it will lead to pinion bearing failure as well as the output of the t-case giving up.

On the pre 96 years, the slip yoke was supported in a housing with a bearing that would help to keep it strait and dampen vibes.

96+, the slip yoke is entirely external with no support, and is not only more prone to vibration, but the vibrations are a lot more detrimental.


Early:
np231j_rear.jpg


Late:
0610_4WD_03_z%2BJB_Conversions_NP231_Mega_Kit%2Bstock_np231.jpg
 
cal said:
On the pre 96 years, the slip yoke was supported in a housing with a bearing that would help to keep it strait and dampen vibes.
Click to expand...

I don't get this.

The mainshaft output bearing in both 95- and 96+ t-cases lies in the output housing that bolts directly to the rear half of the t-case.

The extra tail housing on the 95- does not have a bearing in it IIRC.

So how is one stronger than the other or more susceptible to vibrations?

I've had a '91 with a 3.5" RE lift, t-case drop, and shimmed and it vibrated. Liveable, but it definitely vibrated.
 
MoparManiac said:
I don't get this.

The mainshaft output bearing in both 95- and 96+ t-cases lies in the output housing that bolts directly to the rear half of the t-case.

The extra tail housing on the 95- does not have a bearing in it IIRC.

So how is one stronger than the other or more susceptible to vibrations?

I've had a '91 with a 3.5" RE lift, t-case drop, and shimmed and it vibrated. Liveable, but it definitely vibrated.
Click to expand...

I seem to remember there being a bearing there. I even used to have a photo with a cutout that showed it (but I can't find it now..). I havent had a 231 apart in a lot of years though.

I ran an 87 with 6.5" lift with no sye and no vibrations some years back. Everyone has different experiences.. but we can be pretty sure what experience someone will have with a late model, 6.5" and no sye..
 
cal said:
I seem to remember there being a bearing there. I even used to have a photo with a cutout that showed it (but I can't find it now..). I havent had a 231 apart in a lot of years though.

I ran an 87 with 6.5" lift with no sye and no vibrations some years back. Everyone has different experiences.. but we can be pretty sure what experience someone will have with a late model, 6.5" and no sye..
Click to expand...

Ditto...can't remember the last time I tore apart one of those.

Yup 100% agree.
 
There is a bushing in the early tail housing.
 
cal said:
I seem to remember there being a bearing there. I even used to have a photo with a cutout that showed it (but I can't find it now..). I havent had a 231 apart in a lot of years though.

I ran an 87 with 6.5" lift with no sye and no vibrations some years back. Everyone has different experiences.. but we can be pretty sure what experience someone will have with a late model, 6.5" and no sye..
Click to expand...

On my 1999, I had about 7.5" in the rear on a AX15/NP231 with a super low pinion rear axle on a stock shaft. Against all odds, it did not vibrate, even on the freeway. It did, however, toast a u joint pretty fast.
DO the SYE - its safer :roll:
 
Well my '92 XJ was fine with shims at 4.5" and most peeps were like "Wait u don't have a SYE?" and I wasn't getting any bad vibes

Once I went to 6" though it destroyed my cardon joint in the rear driveshaft and then I had to do the SYE etc.

Since money is tight as it is for most Jeepskates and in todays economy just shim it 6-8 degrees and drop the tcase. I can sell u my tcase drop brackets or my '92 Cherokee Briarwood if u feel older is stronger like most of us on here! ;-P

If you want a 242 with stronger earlier output shaft bearings I can sell that to ya dude! Still cheaper that a SYE no doubt

Can u tell money is tight for me too?

Novak is making prototype billet stuff now for the 242 SYE's IF UR FEELING A SPLURG COMING ON...:spin1:
 
you can always run the tcase drop for a little while if you are low on funds...

I would get a Hack-n-Tap that uses a fixed yoke and go to the junk yard, get a automatic front drive shaft and install it in your rear
 
just got done instaling a sye on my 93. i am currently using a front drive shaft out of a 96 auto. and it is stretched to its max. i definately need to get it lengthened. but before that i ran the stock one with a t case drop, didnt have very noticeable vibes but went through u joints like crazy. mind you i have around six inches of lift (1.5 shackes and brand new 4.5 leafs)
 
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