[JerseyRepresent]

I installed the PORC sye today with a front xj drive shaft. Got everything buttoned up and it seemed good to go. Everything shifts fine so off i go for a test drive. Get around the block and the vibes are worse than they were before. Jumped on the highway just to test different speeds and vibes are all around much worse than they were before the SYE. How is this possible? I know i should put shims in the rear to get the correct pinion angle but is it possible that without them and with the SYE the vibes got worse? There is also a ticking noise while driving. Crawled under the jeep and nothing looked out of the ordinary and nothing was hitting the drive shaft or anything like that. I am so bummed out right now cause i spend a bunch of time working on the heep and now i am worse from where i started. If any one could point me in a direction on where to start i would be eternally greatful. Anyone from NJ got some free time on their hands tomorrow and wanna give me a hand? Thanks so much...

Ps. Its a np231j transfer case with a AW4 tranny..

[xjfever]

For the SYE to work correctly the pinion angle has to be close to perfect. Also did you test the front shaft for straightness and proper balance?

[JerseyRepresent]

After some research i am going to venture a guess and say my pinion angle is all jacked up. What size shims are the norm for my set up? I havent checked the front shaft but its on my to do list for tomorrow. Going to pull the front and drive and see if it helps. Then do the same with the rear. I am pretty sure its the pinion thats causing it. You think if i put my T case drop back in it will help at all?

[shawnzoman]

The drop may help, but you definitely need to get some shims and get those angles right. The pinion yoke should be pointing directly at the output shaft of the transfer case. Also remove the front shaft and drive it around just to rule that out even though an SYE shouldn't mess with the front shaft angles. It's a 10 min job and can't hurt.

[1990JEEPXJ]

how much lift?

[xjfever]

Pinion Angle Alignment - 1 This shows how to measure the angles, it's for a TJ but the only difference is you will need shims instead of adjustable control arms. I don't know how much lift you have but if it is 5" or more the front could be the problem since you have the low pinion d30. I would bet on the rear pinion angle being the problem though.

[JerseyRepresent]

I put a re 3.5 kit on. I got 4.25" lift up front and about 5" in the rear. I agree and think shims are the soultion. Anyone have any tips on where to start with shims. What degree?

[xjfever]

Most likely a 4* shim will put you where you need to be, but it may take a 5* or 6*.

[berg]

I have the same lift. I have 4 degree shim with a HnT SYE and it is PERFECT.

Also.... How long have you been running the lift? The reason why I ask is that mine hasn't really settled that much. I installed it in Oct '09. I'm sitting 5 in the rear and 4 in the front. I installed a spacer in the front to level it out.

[JerseyRepresent]

I was thinking either a 4* or 5* shim too. The lift has only been on since the begining of june, so just about 2 months... I pulled the front shaft this morning and got the same results as yesterday when i took it for a test drive. Then i pulled the rear shaft and drove in 4hi and it was fine. So i am 99% sure that the shims should cure it. Either that or the shaft has to get rebalanced because it was picked out of the JY. But like i said i think the shims should fix it.

I read some posts that said it was ok to drive on the front shaft only if you must as long as you dont abuse it and be careful. I have to drive about 75 miles later today, all highway, and i am going to have to do it with out a rear shaft. I will keep the speeds on the highway no higher than 60 just to be safe. Anyone think this is a horrible idea?

[xjfever]

You should be fine running with just the front shaft. Lots do it after the SYE install while waiting for a custom rear shaft.

[JerseyRepresent]

Perfect thats just what i wanted to hear from the resident expert. Thanks for all the help guys.

[Eggdashure]

Just as an FYI, I had the same problem. Right after I put the SYE on my vibes we're worse than ever. I had a 4* shim and brand new U-joints. What had happened to me is that when I installed the new U-joints, I managed to break one of the U-joint C-clips and pushed the joint partially through the other side. This small offset of balance made the thing vibrate like mad at all speeds. I tossed on an old C-clip and it rode smooth as glass. Just my experience.

[robsjeepxj]

Put the front shaft in the back and see if it's any better. Also you should rebuild the rear shaft anyway especially since you got it from a junkyard that thing could have been sitting there for years the u joints are probably shot. Check the slip joint part for play too. Besides the rear shaft gets used 100% of the time so rebuilding/balancing it is good investment. You needed the shims before that's nothing new you probably just have need to rebuild the shaft or if it's bent or the slip joints shot to get a new one.

[ar4130]

Measure you driveshaft and rear pinion angles as stated above. Sounds like you need at least a four degree shim.

Install them so that they become part of your leaf pack with new centering pins and make sure you put them in the right way (fat side to the back).

When i first installed my shims I put them in the wrong way and threw my angles way off. I installed them with the fat end foward as if it was a spring under set up. Took me a few days before i realized it and turned them around. I ended up using a six degree shim and it was perfect.