BigRedRubi

Background....Jeep is a 09 Unlimited with 4" lift and 34" AT tires. I had the gears swapped to 4.88's and it now has a small vibration that starts at 50 mph and stays consistent as the speed increases beyond that. I pulled the rear drive shaft and all of the vibration went away. Visually, the factory rear shaft looks ok. It does not have adjustable control arms, but the pinion angle looks good. I assume a new drive shaft is my next purchase. Any other thoughts? If I have to go to a new double cardon shaft, is the pinion angle good for that style shaft or will i need to get adjustable uppers?


8.7 degrees on housing.

9.1 degrees on shaft.

resharp001

Possible to source another factory shaft for uber cheap in that area, or borrow a friends? In my area you can buy new take-offs for $50-100. Those factory CV joints are pretty forgiving in the rear. That would be the easiest way to determine if it's the shaft itself, or if something with the pinion flange/pinion ain't right.

I wouldn't go throwing money at an aftermarket DC shaft just yet if it were me, and here's why. You have to remove that pinion flange and install a yoke. In order to do that, you're removing the pinion nut. If you remove that pinion nut, I'd imagine whoever did your regear could then claim "oh, the pinion nut was removed and now the preload is all jacked....WE DIDN'T DO THAT!" I'd just hammer out if this is a coincidence with the DS, or if it's a bigger issues with the gear install. My opinion at least.

You might just try taking it back and complaining about that vibe which was not present before. At least it would be documented then too.