Not Good Vibrations!

[tomplum]

I know everyone enjoys helping diagnose vibrations from the comfort of their own living room... 2004 XC70 105,400 miles. We get a vibration- much like a wheel balance issue. 65-74 MPH. Seems from the front - possibly picking some up when I sit in the back from the rear. Obviously, the speed we normally would like to cruise. I drive the car ~ 25% of the time- and really just enough to know it is different that normal. I went through and did the belt, timing belt, pump, trans flush, plugs etc at 102 K, and had new tires installed (Bridgestone Ecopia Duelers) the week after. The angle gear and RH axle shaft was replaced 14 months and 20,000 miles ago. (The shop had left the large clamp off the CV boot when they did the angle gear, it spun the grease out so that's why the shaft was replaced- showed a Volvo PN on the RO) I don't believe the car was ever quite as smooth after the angle gear replacement, but nothing like this. Upper mount, strut mounts and front trans mounts replaced at 68k.

I've tried different positions on the top mount since I had that off to to the timing belt job, preloaded to various degrees- not preloaded etc. I can't make a CV joint cry for help no matter how I try on tight turns/ accel /forward / rearward . I've only felt the 2 front drive shafts and rear prop shaft whilst being up on ramps, but feel wise- I couldn't determine an issue. While an assistant changes gears, park brake on and I am at the rear of the prop shaft -there is 3/4" rotational travel at the rear of the shaft as it changes direction. The sound when changing gears seems minimal- no big clunk anyways. On mounts, it looks like I am getting some movement at the mount near the lower crank pulley, though I can't really say that I feel a transfer of vibration through the mounts at other times. I've had the tire shop recheck balance.

Any thoughts on the above or a good direction to go from here? If there were a tire defect- what is the likelihood they would have caught it on the balancer? I may rotate next and see if the vibration changes, but beyond that I just don't know. Would the prop shaft normally get lubed after an angle gear replacement? Thanks in advance for thoughts on this. Tom

[tomplum]

An update. I moved the tires front to back and the vibration did change enough to warrant another balance. It had looked to be that one of the weights had come apart. The Firestone dealer gladly did them again , but I have to say it isn't a smooth as w/ the Pirelli's. These tires are not aggressive- yet do have more road noise. Food for thought for anyone tire shopping. My best guess is this tends to amplify a somewhat "normal" driveline w/ 100K on the clock. Any thoughts on this? Does the addition of AWD shafts tend to transfer vibrations around the vehicle more? Maybe there is the start of something wearing. I do know that the original rotors are getting worn and will get replaced w/ pads soon enough. Glad to hear additional thoughts on this.

[tomplum]

I have corrected the vibration. In hopes that this may help someone, the right front wheel bearing was the majority of it all. The nasty vibration that was becoming apparent at highway speeds is gone. Inspect how I may, I found just nominal looseness in the usual other suspects, but none in the hub. I had raised the car and had my other half run the accelerator in gear, and got a whisper of a noise from the RF bearing. When the hub was removed, a roughness could be felt in the bearing. I still wasn't convinced until the roadtest, but it worked out.

[sjonnie]

Yeah, I had a wheel bearing go bad on me that showed no signs of play, however I had noise to give it away.