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Are my shocks bad?

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by DirkAshburn, Apr 6, 2020.

  1. DirkAshburn

    DirkAshburn Junior Member

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    Hello everyone. I recently bought a used 2011 Prius. The rear (especially rear right) vibrates when the car hits 45-50mph (most evident at this speed). I can see the rear end window actually shaking. It smooths out over the highway where the road is smoother.

    I've had it looked at several times by my local shop. They said the tires were cupped, so we replaced all 4. They inspected the tires and everything that connects to it and everything was fine. Balanced and aligned. Problem is the same.

    Could it be the shocks? How can I tell if they are going bad? I have the tools I could replace those myself.
     
  2. tankyuong

    tankyuong Senior Member

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    Sounds like shocks
     
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  3. DirkAshburn

    DirkAshburn Junior Member

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    I forgot to mention (and dont see a way to edit?) it's at 114k miles.
     
  4. sam spade 2

    sam spade 2 Senior Member

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    Could be a bent wheel or a bad wheel bearing......or shocks.
    Sounds to me like you need a different shop.
     
  5. Jim Swart

    Jim Swart Member

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    Yup.... time to replace them.
     
  6. Montgomery

    Montgomery Senior Member

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    Bad bearing or shocks I'm guessing also.
     
  7. 2012 Prius v wagon 3

    2012 Prius v wagon 3 Active Member

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    Yes, really. Such a typical sad story: "OK, we'll test this and that, replace a bunch of things for you, did not help, can't figure it out, $600 later, shrug. We're professionals. Says so right on the invoice. Maybe you'll have better luck with people who can't even see your car, but can read your description on priuschat."

    Since you isolated it to the right rear, I would have at first swapped wheels left to right, which may have saved you some $$ and them some confusion. You may still want to swap, just in case it is a wheel problem rather than a tire / mounting / balancing problem.

    I'd then check for worn suspension components. A worn bushing may result in an instability which gives you that vibration. And yes, maybe shocks.
     
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  8. Borninblue

    Borninblue Active Member

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    Both my rear bearings were shot for my Gen 3 at 140K for what it’s worth.
     
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  9. edthefox5

    edthefox5 Senior Member

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    Bent wheel.

    I went through hell on my G2 trying to find shaking. Vibration. New tires new struts all around same thing. Finally out of exasperation went to another tire place. Car up on the lift 10 minutes tire guy says you have some bent wheels.

    Here's what you should do. Take the car back to the tire shop. Put it on the lift. Spin both rear tires they should have no run out (wobble) whatsoever. None. Even the slightest wobble will be felt at speed. Wobble is bent wheel.

    It is the premiere way to check for bent wheel. Spin all the tires on the back. Fronts dont spin freely.
    Swap the front tires to the back and spin them and watch closely. I will bet you have a bent wheel maybe more.
    Its really easy to bend these they are tiny light wheels.

    My G2 had 3 bent rims. One bad 2 not so bad. First tire shop never caught it $1500 later.

    Apparently my wife loves hitting pot holes real hard.:X3:
     
  10. 2012 Prius v wagon 3

    2012 Prius v wagon 3 Active Member

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    And if you have a bent wheel, and are able to swap wheels around by yourself, that will make it easy to confirm and isolate. A bent wheel on the front will be easily felt through the steering wheel, and will be very different vs. what you're feeling on the right rear.

    It might seem that the mounting and balancing, with new tires would mean there cannot be a problem, but there can. The wheel might be dynamically balanced, which means the mass is balanced, but if the wheel is bent, the tread itself may be non circular or may be wobbling as the wheel goes around.

    Road force balancing is a step up from regular dynamic balancing, and would catch such a problem. This link has a good explanation of what it is and when it may or may not be warranted.

    When is Road Force Balance Overkill?
     
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  11. DirkAshburn

    DirkAshburn Junior Member

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    Thanks guys, going to get the wheel checked for bend tomorrow. Will update!
     
  12. DirkAshburn

    DirkAshburn Junior Member

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    Got it back from the shop. No wheel damage whatsoever. They took it to another shop nearby that did a 'road force balance'. That seemed to have done the trick, the vibration is severely reduced. They checked the shocks as well, said they are fine. Anyway will see if this did indeed fix it after a driving it more.
     
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  13. tweedle99

    tweedle99 Member

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    I replaced mine at 100k. They look perfectly fine, no leak or wet spot. Once i took them out, they dont even extend back out anymore. According to other threads, internal leak which can't be seen
     
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  14. DirkAshburn

    DirkAshburn Junior Member

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    Yeah I'm going to go ahead and replace the rear shocks too, they are on order.
     
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  15. 2012 Prius v wagon 3

    2012 Prius v wagon 3 Active Member

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    Were they performing well (i.e., providing damping in the suspension)? Do you know what it means when they don't extend? There is a good chance they were fine, if the lack of extenion was the only thing you noticed being wrong.
     
  16. edthefox5

    edthefox5 Senior Member

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    Got it back from the shop? You did not watch them do the rear wheel spin?
    I would have.

    The fact that force balancing improved it tells me there’s something not right with a wheel.
     
  17. 2012 Prius v wagon 3

    2012 Prius v wagon 3 Active Member

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    I agree about the road force balancing. Great, accurate details in that link I posted above, but basically a regular balance (dynamic wheel balancing) ensures that the mass of the tire is balanced, but does not even try to see if the wheel is round and straight. The road force balancing takes it to that next level, also factoring in variable stiffness in the tire. Much more involved.

    The fact that you had this problem with the old tire, and also with the new tire suggests that the tire was not a problem. Not likely that the old and new tires are both bad in the same way, so they're probably both good. And if it really got better with the road force balancing (seems odd to me), then it might be a wheel issue. If the wheel is slightly out of round, the strategy would then be to set the tire so its most compliant part is aligned with the highest point on the wheel so the two are offsetting.

    So I hope your problem is solved, but I would not bet money on it.

    BTW, sometimes something as simple as having some debris on the wheel-to-brake rotor interface, or not torquing the lug nuts carefully, etc. can cause a wheel to have some wobble to it. In that case, simply removing it, cleaning both surfaces, and reinstalling carefully will fix things. Much tougher to deal with something like this if you're not sure of the competence of the people touching your car.
     
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  18. tweedle99

    tweedle99 Member

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    They seemed OK. Car only bounced once when pushed down on the back.

    When i got them off the car, i compressed the shock w/ the floor and it never extend fully back so there was no more dampening.

    I did the same w/ new shock and it extend back to full extension in a few seconds. I've read that a lot of ppl saw the same thing when they replaced their rear shocks.


     
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  19. 2012 Prius v wagon 3

    2012 Prius v wagon 3 Active Member

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    They are probably fine for normal use. If you plan to do a lot of off roading or track racking, off-road racing, or street racing through the potholes of Detroit, you should probably replace them.

    Bounce test and no other problems means they are doing their job, which is to provide damping.

    Contrary to what you said (I bolded above) the fact that one does not extend means that the Nitrogen gas has probably leaked out. If all the oil is still in there (has not leaked out, leaving a trail) it will provide damping except for in the extreme conditions I listed above. So the damping is still there. Failure to extend means the gas has leaked out, but not necessarily the oil.

    Shocks + struts are typically charged with Nitrogen gas. The pressure keeps any bubbles small. Usually that does not matter, but when the car is used in extreme conditions, enough bubbles could be formed from rapidly driving the oil through the damper orifices that the gas pressure would help keep them in check. Side effects of that gas is that the strut rod will extend when the strut is removed, and it also adds a small amount of additional effective spring stiffness.

    And "a lot of ppl" are very often wrong, about many things. Most don't know much more than how to use an iPhone, where they efficiently get their knowledge from other such people and spread it to others.
     
  20. tweedle99

    tweedle99 Member

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    There was no oil leak but definitely no gas left. In my case, since the shock is not extending, the only dampening is done by the spring. Potholes are not the only obstacle in our daily driving. Parking lot w/ closely spaced speed bumps are more common down here in Texas.

    The "a lot of ppl" was not about their knowledge but more what they observed of their old shocks.