I’ve been procrastinating a fix for a vibration that is speed related on my xc90. It starts around 45mph and comes and goes up to 65 or 70… I broke some stuff ‘diagnosing’ it, and once I fix that I’m going to take the awd driveshaft out. I’m assuming a bearing is bad, any ideas? I want to repair the driveshaft because it’s really expensive to replace.

  • @mvirtsOPEnglish
    1•1 year ago

    1. Lol I thought it was the front left half shaft, took it all apart, destroyed the lower ball joint, took the lower control arm off to hit the ball joint out of it on the vise, put a new ball joint in, put the lower control arm on, torqued it to spec and lowered the vehicle. I thought it was just bad alignment until a shop told me the bushings are shot :/

    2. I looked at the driveshaft and there’s grease spray on the heat shield near the u joint in the middle. I think i got it to just barely move when I was under the car but I don’t have a lift so it was awkward and blocked by exhaust parts. I figure it’s worth taking it out to inspect, plus this car should drive just fine in fwd without it, so I can see if the symptom goes away…

    3. I can when I get around to it, not much to record for symptoms but can definitely get pictures.

    It’s like the car is handling fine, not and extreme shake or anything. You start to feel a subtle shaking like what some roads will feel like, but it’s speed dependent and happens everywhere. It could be that the driveshaft is out of balance, idk.

    Grease? What grease? :P yeah I need to grease everything. Is it possible that greasing all the joints could fix something like this? Also, I don’t think many of the joints have grease fittings but I also haven’t looked thoroughly.

    • Wrench WizardMEnglish
      2•1 year ago

      It happens! And busted bushings will cause a bit of vibration by their self! Although it would be constant I think.

      Anyway, breaking things is a great way to learn!

      The grease spray, is it recent or dried up? If a cap has somehow blown the grease out that would indeed cause a vibration as the needle bearings inside will eventually fall out of wack. Have you checked the caps around the U-joints?

      Other than that, can you describe the vibration? Is it a slow, steady hum almost or more of a grind? Does the vehicle bounce or shudder when this happens?

      The brakes can sometimes cause this as well. After a trip, walk around and feel your rims, or the calipers themselves if you can get to them. If they’re extra hot, or any one is much hotter than then rest you have a brake stuck which can be a simple fix!

      A loose lug nut would also be worth checking, are they all tight? Any signs of wear around them where the tire has shifted?

      Also, the cv joint, is it leaking around the boot at all? Transmission fluid perhaps?

      If you want to start with something simple (and free!) You can check your wheel alignment at home, here’s an article that explains better than I can!

      https://tiregrades.com/tire-maintenance/alignment/how-to-do-a-wheel-alignment-at-home/

      Iirc this is recommended to be done every 15k miles anyway. I’ve seldomly met anyone that actually follows it so strictly, not even myself so I’d recommend it even if it doesn’t resolve our issue.

      Whether you’d want to adjust it yourself if it is indeed out of wack is up to you. It’s much cheaper but alignment can be fickle. If nothing else it’s free!

      I’ll get back when I have more time, hope this helps!

      • @mvirtsOPEnglish
        1•1 year ago

        Im pretty sure the grease spray was old and dry

        The vibration is low frequency shaking, no grinding, doesn’t interfere with driving really.

        I put a new lower control arm in on the left side today and it improved the handling issues some, hopefully when I do the right lower control arm it will be better. I noticed that the thing about torquing the bushings on the ground doesn’t apply to this vehicle… so idk why they broke when I was breaking things before, maybe the bushings were on their way out anyway.

        You do have me hoping that replacing the control arms may fix the vibration… hopefully I’ll know soon!

        Ah and I learned the hard way that when trying to get the ball joint in the control arm, if the knuckle has a mind of its own and gives you hell for an hour, make sure both sides of the vehicle are on stands so the sway bar isn’t ruining your day 😅 I’m so glad I got it done all at once, I’ve already scrapped one car because I left it taken apart for too long 😬 One is enough.

        I definitely want to check my alignment at home, thanks for the info!

        Good point I should check all the wheels…

        I haven’t gotten a good look at the joint in the drive shaft, which is part of why I want to remove it.

        Thanks for the advice! It helps a lot