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Discussion Starter · #1 ·
After I installed the 2.5" RC lift I took it for a drive and noticed there was a vibration. I've read a lot on the forums that this issue might happen so I bought some washers and dropped the transfer case 1". I marked the slip yoke to see how much difference before and after the t/c drop, but it was the same. Took for a drive to see if there was any change and it was exactly the same. I still need to upgrade my wheels and tires so I'm looking for an economical way to smooth out the vibrations. Thanks in advance.
 

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My first suggestion is to get a real transfer case drop kit, which consists of two pieces of 1" square tubing with three holes drilled in each at the correct spacing to accept the skid plate bolts.
Then check your motor mounts and transmission mounts.
When does the vibration occur? Acceleration or deceleration? What gear(s)? What RPM?

Is that a CherryBomb muffler acting as a cat?

Good Luck, L.M.
 

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'89 YJ 4.2 with MC-2150 Carb & HEI, 2-1/2" Ex. AX-15, NP231 SYE, Adams shafts, F&R ARB, 3
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Post a pictre of your entire rear driveline so we can see the TC and Pinion angles. As level as possible when you take the pic
 

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Discussion Starter · #6 ·
My first suggestion is to get a real transfer case drop kit, which consists of two pieces of 1" square tubing with three holes drilled in each at the correct spacing to accept the skid plate bolts.
Then check your motor mounts and transmission mounts.
When does the vibration occur? Acceleration or deceleration? What gear(s)? What RPM?

Is that a CherryBomb muffler acting as a cat?

Good Luck, L.M.
The vibrations starts around 15-20 mph, I didn't take it out over 45 mph and the vibration was pretty much the same as it is when going slower. Seemed to be slightly worse when decelerating.
 

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'89 YJ 4.2 with MC-2150 Carb & HEI, 2-1/2" Ex. AX-15, NP231 SYE, Adams shafts, F&R ARB, 3
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Always hard to tell from a pic, but it looks like your driveshaft angles are out of alignment, Pinion is pointing to transfer case, transfer case is pointing straight back. slip yoke driveshafts like to be on paralell angles where SYE's work better when the angle is closer to what you have now. I would check into those with an angle finder. A decent one can be had for around $10. Easily fixed with a set of shims, removing the one's you may have installed already may be causing your issue. I can't see the leaf sprins and ubolts to really tell
 
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After I installed the 2.5" RC lift I took it for a drive and noticed there was a vibration. I've read a lot on the forums that this issue might happen so I bought some washers and dropped the transfer case 1". I marked the slip yoke to see how much difference before and after the t/c drop, but it was the same. Took for a drive to see if there was any change and it was exactly the same. I still need to upgrade my wheels and tires so I'm looking for an economical way to smooth out the vibrations. Thanks in advance.
In addition to the above info, check the u-joints for wear. The slightest angle can cause a worn u-joint to vibrate.
 

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Need to shim Axle. Angles are off.

4487155
 
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Need to shim Axle. Angles are off.

View attachment 4487155
Or, drop the transfer case more. Maybe add a 1" motor mount lift. The ultimate cure will be a slip yoke eliminator.

How much of a lift does the Jeep have? A TC drop will work up to a 2 1/2" spring lift.

Good Luck, L.M.
 
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