Had a friend who brought their 04 Jeep over complaining of a vibration. Took it for a drive and defiantly has a vibration under acceleration and above 35mph. One of the rear U-Joints appeared to have a little play in it, but decided to go ahead and replace both U-Joints on the rear shaft. Got it all back together and there is still a vibration. The new U-Joints did seem to reduce the vibration, but it's still there. Next I decided to remove the rear drive shaft, and took it for a quick drive in 4-hi and no vibration. Opened up the rear diff and found there was some water that got it somehow. After getting the fluid drained and everything cleaned up a bit, noticed some pitting/gouges in the spider gears. Also, noticed one of the spider gears had quite a bit of play in it. I'm inexperienced when it comes to differentials and what is acceptable, but both of these findings tells me they have have some problems. My question is, would the spiders gears being chewed up and the fact that one of them appears to have quite a bit of play be the cause of the vibration problem? I tried to get as good a pics as I could.
Driveline Vibration
- Thread starter Billy06
- Start date
Rubicon88
TJ Addict
Rubicon88
TJ Addict
How much play in the backside of the T-Case? You've eliminated the rear DS but that also opens the door for two other possibles.
The diff and the t-case.
With the DS attached the backside of the T-case will turn.
The diff and the t-case.
With the DS attached the backside of the T-case will turn.
Not sure I fully understand what you're asking, sorry. Yes, with the drive shaft attached the transfer case will turn. Or is does in the current state, which is with it on jack stands and in neutral. The play in the spider gears is probably minimal. Both the top and bottom spider gears have a little play in them depending on the orientation of the gears. The cross-pin shaft moves around a little as well if I spin the tires by hand. That movement is more up and down and not side to side, if that makes sense. Not sure if that's normal or not?
I've read that the pinion angle can cause vibration, but this is a stock jeep, so haven't given that much thought as it being the issue.
It's stock height currently, but looks like it could have been lifted at one time. It has a rear track bar relocation bracket and has an adjustable front track bar, which is too long for the stock configuration, and appears to have a dropped transfer case. I'm still new to the TJ platform, so trying to figure this thing out without any info on it's history is a bit of a head scratcher.
I will take a look at those tomorrow. I checked the engine mounts and they are good. It's an 04 that's in good condition with 75,000 miles. Don't appears like much ha been in regards to preventative maintenance though.
If it has the remnants of a lift on there that is an issue. The tcase drop will give you the acceleration vibration you are describing so I would start there. You will want to remove the track bar bracket in the rear to allow the axle to be centered which will help the driveshaft as well.
Good post, an axle that isn't centered introduces another angle into the equation.
Don't rule out shaft balance, but normally that is present at higher speeds.
It's possible a lift was removed and pinion angle wasn't reset, be all over that.
You are doing good, and it was really cool all you did to help him.
Thanks, just trying to help him out the best I can and hopefully learn something new along the way. Lucky for him I'd rather be in my garage than just about anywhere else. I'll check if the rear axle is centered. I had to re-center the front axle due to the aftermarket track bar and it was way off center. Looking at the back, it didn't appear to visually be very far off, but I'll give it a closer look.
Back to my original post, the top and bottom spider gears do have some material missing off them. Not sure if I would call it pitting or gouging, but could this be part of the vibration problems or a whole different problem? Also, when you spin the gears around by hand the cross pin has some up and down movement, and not sure if that is normal or not, and if not, could that be part of the vibration issue as well?
if we can get Rob the gear guy to pull up he would know better than me I certainly wouldn't be comfortable seeing that scarring... I can't get him to pull up on the menu when I use the @ signal.
So, I was able to talk to one of the previous owners of this Jeep and got a little history on it. At one time it had a 4" lift on it, which explains the transfer case drop on it. Whoever removed the lift left the adjustable front track bar, rear track bar relocation bracket, and the transfer case drop. From what I was told, it's had the vibration problem since the old lift was removed. At this point, my friend decided to just put a small lift back on it. Might do what I just did to mine, which was the Pro Comp 2" springs and Rancho shocks. I'm going to go ahead and replace the damaged spider gears, then put the small lift on. Hopefully that cures the remaining vibration issues, as I can't identify any other issues that would be causing it.
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