Bigdp55

Hi I installed a 4.5 RE lift and I had to put in a sye for the rear driveshaft so I have a new driveshaft. Now I have the issue with the front driveshaft vibrating. If I install a T-case drop kit will it help with driveline vibrations? I know I should go get a new font driveshaft but I would rather hold off until spring.

JeepingDan

How are the U joints in the front shaft? I'd look at that first before thinking about a drop kit. Any little binding in the caps will cause issues after a angle adjustment.

Bigdp55

The U joints were checked and from what I was told by a mechanic is that they were fine and he suggested to me that I should get a t case drop

bad_idea

No.

If you have a SYE, then that means you should have double cardon driveshafts on each axle. Means the driveshaft will have two u joints w/in inches of each other at the transfer case, and another u joint at the axle end of the driveshaft. The pinion shaft of the axle and the driveshaft should be damn near straight to each other. If not, then that will cause vibrations.

Does your steering wander? If your caster is way out, your front driveshaft angle is too. They are directly related. Front driveshaft angle is adjusted by shimming LCAs at the body mount, or longer arms can be used if it needs major adjustment.

Rear driveshaft angle is adjusted with shims between the leaf spring and the spring perch.

Ozalid

Hi, did you do your own SYE install ? If not what did it cost ? I have a 3-1/2" lift with a transfer case drop. But I still have vibration at 25mph ..I may have to go with an SYE....Don't really want to...

bad_idea

I did my SYE for about $225 or so. Used the PORC full SYE kit.
Used a front XJ driveshaft of appropriate length. Measured length needed, and found the right length one at the scrapyard. Used my stock front shaft in the rear temporarily until I sourced one from the boneyard.

I set the pinion angle when I welded the spring perches on the 8.8 I swapped in. If retaining your axle (most common), then you will need to shim axle to point at TC. Shims can be had on Amazon for $40 or so.

The cost was negligible, compared to the headache of installing it. I pulled the transfer case out of the jeep to install the SYE. Didnt want to lay on my back under the jeep. Either way, you have to tear the whole transfer case apart. Took me about 6 hours start to finish. I'm fairly well skilled and have all needed tooling available. For the novice, I would likely double that time estimate.

SexyDexy

I would pull the front driveshaft off and take it for a test drive.

Even though the u-joints appear to be okay, the centering ball yoke needle bearings could be toast causing the vibration.

Bigdp55

If the bearings were bad wouldn't the shake be worse if I used 4wd? BTW I have a np231 TC. I do need to get an alignment done the guy who installed the kit did do a tape measure alignment but the steering doesn't wander.

bad_idea

I would guess (emphasis on guess) that the vibration would be less when in 4wd. My ASSumption being the vibration would go away in 4wd because power being applied to the bearings would take the slop out.

Bigdp55

When I use 4wd the vibration stays about the same. Either way I'm getting an alignment before I do anything else so hopefully that might help a little. I'm planning on putting in a adams driveshaft to replace the front one some point soon. I'm just wondering if I could just get away with a TC drop and alignment for now then an adams this spring?

SexyDexy

Make sure your pinion angle matches your CV driveshaft angle.

Bigdp55

My rear driveshaft is at the correct angle but since my front driveshaft isn't a double cardan the angle wasn't altered.

Bigdp55

I would like to say thanks to everyone for the information. I hope my vibration issues won't cost me a fortune to correct.