Hi All,

I have a mild, high frequency vibration at speeds over 60. It has a slight pulse too it. My thinking that since its higher frequency that its the drive shaft, as opposed to tires. It should be noted that I drove without the rear uppers but with the lift for about 4.5 years.

Here are some details:

- 2008 2dr with a 2.5" lift and stock rear drive shaft.
- Adjustable upper control arms, stock lowers.
- Pinion is pointed up, but it could use to be pointed up a little more (see photos below)
- I have 33" tires with 4.56 gears, so fairly high driveshaft speed.

Here are photos of each joint on the rear shaft. You can see that the rear is pointed a few degrees lower than it should be. So maybe it needs to be pointed higher? Or maybe the CVs got badly worn from running with the stock pinion angle, and pointing it up caused them to move into a different wear zone?

The front drive shaft is also stock. I mostly feel the vibration through the gas pedal and the floor, none in the steering wheel.

Guess my question is, do I need to go with an after market shaft, and if so, is the rear drive shaft angle adequate?





Thanks!

 

Speed related vibrations are almost always tire related. Probably have one or more out of balance. Your pinion angle looks fine.

 

Just a couple random thoughts ...

I had a similar vibration and it turned out to be the balljoints.

To test your driveshaft idea, pull one and drive around without it (yes, you can pull the rear and drive around in 4WD).

To test tires, rotate your spare around. But check tires visually for damage--especially cupping. Cupping could be caused by one bad shock absorber, but present on multiple tires as you rotate them through that position.

 

x2 on pulling each shaft and going for a drive, should help to confirm/eliminate them.

You could also go out to Tom Woods driveshaft website and check both the JK and Tech Info areas. Lots of good info to read through, including a few charts of driveshaft angles for stock and aftermarket shafts.
Stock - pinion roughly parallel to tcase output.
Double cardan - pinion pointed up towards the tcase output.
Just from the pics, the angle doesn't look bad at all. (compared to many I have seen on here...)

 

Ball joints can't cause a vibration, but loose/worn ball joints will let you feel a vibration that is caused by a rotating part like unbalanced tires or a bent axle shaft.

 

I'm not going to argue the point. I told you that I had the same problem OP describes, and I told you what i had to do to fix it. That fix has been good for 20K+ miles now.

 

I had a vibration just like that. It sounds like a classic driveline vibration.

I would check the following:
1) a stock cv drive shaft isn't meant to have the same pinion angle as a u joint shaft. Make the angle more like stock greater differential between pinion and shaft.
2) is there any play in either front or rear DS? If so, replace
3) is pinion loose?
4) check you transfer case yoke front and rear for play
5) take front shaft off and drive then rear to pinpoint the issue

Or

Take it to a driveline shop for a test drive and opinion.

 

Figure out the issue? Same symptoms as OP just started. Begins to hum/vibrate (also audible) at 60 then smooths out after 80. Very distinct feel unlike a tire being out of balance.

 

I ended up replacing the front drive shaft with one from Tom Woods (amazing quality). The slip joint on the stock one was worn. The CV and u-joint were pretty decent really.

That got rid of most of it, but still have another smaller one that I am trying to track down.

 

Brought mine to shop. They did say my pinion angle was a bit off so they adjusted the caster. Vibration still there but now ride is flighty especially the front. Then removed front shaft and no more vibration so they are suggesting to replace both front and rear with aftermarket DS (South Bay Driveline in San Jose). Another shop is recommending Coast Driveline. Any experience with those compared to Tom Woods or JE Reel?