2" Lift Vibration

[loki45]

Well, I measured on the Diff cover and the Tranny like you guys said and here's what we got:
Joint out of back of transfer case: 4*
Pinion: 9*

 

[garr]

I just picked up an 01 XJ front drive shaft for $50 in excellent shape, I purchased spicer part # 211229X, Does this part work with the 01 front shaft?, The dimensions of the part that houses the centering ball are smaller on 211229X than on the Part that was on there.

 

[Mtb Jak]

hey im in adkj too

I got a RE one inch transfer case drop, if your interested.

Im doing the Hack and Tap right now and I dk this is hard to me :gonnablow

 

[RCP Phx]

Same difference - point is, the J model transfer cases seem more prone to vibrations.

Still havent figured out what you meant by this,they are all J cases except the pre-chrysler years.

 

[J-Roc]

The output shaft is NOT longer,the housing got shorter leaving more of the shaft unsupported!

not the case according to Mr. Woods

Pre 95

Post 96

http://www.naxja.org/forum/showthread.php?t=80289&highlight=242+machine

Don't do a hack and tap... otherwise it will end up looking like that. I wanted to do the same thing with my 96 np242 but now I am thinking otherwise. New model 242's are definitely a pita!

 

[comanche91]

Well, I measured on the Diff cover and the Tranny like you guys said and here's what we got: Joint out of back of transfer case: 4*
Pinion: 9*

Well, I measured on the Diff cover and the Tranny like you guys said and here's what we got: Joint out of back of transfer case: 4*
Pinion: 9*

Are you talking about the u-joint working angles? If so, sounds like you have a problem here - 5* difference. Ideally, the working angle of the rear diff joint should be 1*-2* lower than the front (non-SYE), so when accelerating and the pinion comes up the working (or operating angles) of the driveshaft are nearly equal. Before you do anything, like dropping the t-case (never recommended), etc., read the driveline measurement instructions on Tom Woods' site, get an angle finder, measure your rear driveshaft slope, tranny and diff angles as compared to parallel, and calculate your u-joint working angles. Most likely your diff pinion will need to be lowered with leaf spring shims.

 

[loki45]

Are you talking about the u-joint working angles? If so, sounds like you have a problem here - 5* difference. Ideally, the working angle of the rear diff joint should be 1*-2* lower than the front (non-SYE), so when accelerating and the pinion comes up the working (or operating angles) of the driveshaft are nearly equal. Before you do anything, like dropping the t-case (never recommended), etc., read the driveline measurement instructions on Tom Woods' site, get an angle finder, measure your rear driveshaft slope, tranny and diff angles as compared to parallel, and calculate your u-joint working angles. Most likely your diff pinion will need to be lowered with leaf spring shims.

Thanks everyone. My mechanic says he can't get my 6* shims in to point the pinion down. That seem odd to anyone?

 

[comanche91]

Thanks everyone. My mechanic says he can't get my 6* shims in to point the pinion down. That seem odd to anyone?

I got mine here:

http://jkwoffroad.com/offroadproducts.php

 

[MasterShakeXJ]

i just dont see why you would need to do any sye with only 2 inches of lift? did you get an alignment after you did your lift?
6* shims for a 2" lift???

 

[comanche91]

i just dont see why you would need to do any sye with only 2 inches of lift? did you get an alignment after you did your lift?
6* shims for a 2" lift???

I don't see anything about a SYE, and do agree 6* shims might be a bit much - I needed 4* w. a 3" lift on my MJ. He needs to shoot his driveline angles with an angle finder, calculate the u-joint working angles, then buy the appropriate shims.

 

[loki45]

Tranny pan is 4.4*, Diff is 9. Driveshaft angle is 13*.

 

[lancey3]

This is a way over posted thread. Shim it, if thats not enough t case drop. Case closed. An SYE at 2 inches is overkill imho.

 

[comanche91]

Tranny pan is 4.4*, Diff is 9. Driveshaft angle is 13*.

I'll just ignore the previous post. :wierd:

These were my readings after a 3" lift (91 MJ LWB):
DRIVE SHAFT SLOPE: 8* DOWN
TRANSMISSION ANGLE: 6*
PINION ANGLE: 9*

Okay, if your driveshaft slope angle is 13* (seems high, mine was only 8*, but my driveshaft is a lot longer), the front u-joint operating angle is 8.6* (13 - 4.4). The rear u-joint operating angle is 4* (13 - 9). You have a 4.6* difference between the front and rear joints. You want the two u-joint operating angles close to the same, or the rear a degree lower that the front to compensate for the pinion rising up during acceleration. So if your readings are correct, I would think a 3*-4* max shim is all you'll need. Make sense?

 

[loki45]

I'll just ignore the previous post. :wierd:

These were my readings after a 3" lift (91 MJ LWB):
DRIVE SHAFT SLOPE: 8* DOWN
TRANSMISSION ANGLE: 6*
PINION ANGLE: 9*

Okay, if your driveshaft slope angle is 13* (seems high, mine was only 8*, but my driveshaft is a lot longer), the front u-joint operating angle is 8.6* (13 - 4.4). The rear u-joint operating angle is 4* (13 - 9). You have a 4.6* difference between the front and rear joints. You want the two u-joint operating angles close to the same, or the rear a degree lower that the front to compensate for the pinion rising up during acceleration. So if your readings are correct, I would think a 3*-4* max shim is all you'll need. Make sense?

Yup Yup. Thanks all.

 

[wjp]

Tell me how you make out . I want to do a 2" lift for my 2000 cherokee. I wanted to go 2" hoping I would not get vibes, but that doen't seem to be the case. I don't want to spend the coin on an SYE.


Thanks,

Jim

 

[garr]

Tell me how you make out . I want to do a 2" lift for my 2000 cherokee. I wanted to go 2" hoping I would not get vibes, but that doen't seem to be the case. I don't want to spend the coin on an SYE.


Thanks,

Jim

I lifted my 2001 XJ 2" & had bad vibes, My Driveshaft guy recommended I try a shim before going for a SYE & DS, We tried the shims & the vibes did get better but were still very bad from around 30 to 38 MPH. I gave up & installed an HD SYE, $60 Front Driveshaft & 3* shim; All vibes are now gone!!.

 

[comanche91]

I lifted my 2001 XJ 2" & had bad vibes, My Driveshaft guy recommended I try a shim before going for a SYE & DS, We tried the shims & the vibes did get better but were still very bad from around 30 to 38 MPH. I gave up & installed an HD SYE, $60 Front Driveshaft & 3* shim; All vibes are now gone!!.

Yeah it seems the 1997+ models are much more susceptible to vibes even after modest lifts. I fought vibes for about a year on my MJ after lifting at the same speed range. Turned out to be the diff. I had regeared right after the lift and the pinion backlash was basically zero, there was none, and it caused driveline vibes. Changed the gears myself like a dumbass. Never again.....:flamemad:

 

[CJ's98XJ]

I would start with the inexpensive stuff first. Try dropping yur TCase.

 

[MasterShakeXJ]

ive never understood the t-case drop. you lift your jeep for more ground clearance. and then lower one of the most important parts of the jeep. doesnt seem logical to me.

 

[lancey3]

ive never understood the t-case drop. you lift your jeep for more ground clearance. and then lower one of the most important parts of the jeep. doesnt seem logical to me.

You gain 3-4 inches of clearence through suspension and you lose one from the crossmember then you gain 2 or so in tires.