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Hello AI, I have a 2011 Scion tC with a 2.5 L, four cylinder engine and ~65k miles on it, it is stock besides some window tinting. Over the past year or so the car has developed a very strange, uh, wiggle? Shake? Shimmy? Something that is disconcerting. My best attempt to describe it is this: above a certain speed the rear of the car feels like it moves as though I just jerked the steering wheel to correct something. The critical speed depends on the road surface, on some roads I can do 75 mph with no problem, on others it'll begin to move oddly at 35. It's even lane dependent, some roads are fine at 45 in the left lane, but not the right. It's worse/more pronounced when the road is wet, and when I'm going around a left turn, and I think even when it's cold but that part is new. There's no steering wheel feedback at all when this happens. I've driven behind the car and it really does look like the driver has spaced out a bit and then jerked the wheel a bit to catch up to whatever turn they were supposed to be making, the back end moves rather noticeably. Initially it was just a weird movement when taking left turns at speed, like a flyover interchange, in the rain. Now it's pretty frequent. Stuff that probably isn't within "normal" car use: I drive over a lot of speed bumps. Like 10+ a day. I work on a military base and the gate lanes have at least five rather aggressive bumps in both directions. It can get to 20 times a day if I leave for lunch or a meeting or whatever. I probably need to replace the shocks, but I also don't think just the shocks could be responsible for this issue? My wife is hard on vehicles. Particularly the rear passenger tire, which she runs into curbs with some frequency. Many years ago someone in a parking lot backed into the passenger side of the car, but everything was repaired. Beyond that it's just a daily driver vehicle. I appreciate any insight into what might be causing the problem, and how I get it fixed.
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Nov 6, 2021 07:05
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| # ¿ May 14, 2024 20:40 |
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You are correct that I am not a car expert. I am an engineer, I have a couple of degrees in nuclear engineering that included some mechanical adjacent education for power plant operations. In theory I should be able to understand most of what makes a car go, but having an education in the fundamentals doesn't translate to actual working knowledge of the system very well. I've worked on my vehicles before, but nothing more involved than replacing rotors/pads. This may have been around longer than a year? Time has been weird since the pandemic started. I know that I've had the car aligned, front and rear, and the tires on the rear replaced since the problem showed up. At one point in time there was a seriously uneven wear on the rear passenger tire but it's been "addressed" before. The current wear seems slightly asymmetrical? I can't actually tell. Rear tires:   I don't know if the car came with a sway bar, but I considered installing one to address the symptoms but that won't solve the actual issue and I'd rather do that.
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Nov 6, 2021 21:18
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Thank you for all your help, I was able to begin this whole investigatory process much better informed than I otherwise would have been. Bushings and joints are all fine. Turns out that both the struts and shocks were totally gone and the oscillation was probably because the suspension wasn't able to damp any of the road issues. This was combined with a pretty rough front alignment, which seemed to be pushing everything around even though it felt very much like it was the rear of the car that was haunted. Replacing the suspension bits with the help of a coworker and getting new tires and an alignment has resulted in a 99.95% reduction in ghosts haunting the car, and the remaining 0.05% is probably just regular road induced movement that I'm hyper-vigilant to and would ignore in any other car. It's much nicer to drive now. I'm not certain what caused the front alignment to be so bad in the first place, but that's an issue for another day. E: Holy cow this was from a year ago wtf.
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Nov 27, 2022 23:29
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A twist, the car is still haunted. But only a little. Normal driving has no issues, and several locations that used to be problematic are not. But the OG location for the ghosts to appear still causes problems. A flyover from one highway to another, a left turn that both ascends and descends in elevation. And I generally drive pretty aggressively anyway. Those signs about 40 mph are bullshit, you can easily do 60 and not even load up the suspension very much. My coworker thinks it might be pillow ball joint problems in the rear of the car.
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Feb 4, 2023 17:45
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Applebees Appetizer posted:Odds are if the front struts were shot the rear ones are too, might wanna start there. New struts in the front with blown shocks in the rear are gonna make for a weird handling car The rear ones were replaced at the same time as the front. We did the whole coilover in the front and the shock in the back, the old springs are still back there though. You are correct, they were all absolutely shot.
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Feb 5, 2023 02:02
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