"Vimto" (smudgey)
08/12/2014 at 10:16 • Filed to: None
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"Vimto" (smudgey)
08/12/2014 at 10:16 • Filed to: None | 0
| 17 |
Hi guys,
As some of you know I have a 2007 Mercury Grand Marquis LS. I just took a 600 mile roadtrip and noticed that between 55 and 70 mph, it STILL has a lot of shake going on.
Backstory: I bought the car in February with 74,500 miles. It had BF Goodrich tires on it that looked very old, but had decent tread. I live in Pensacola away from my parents, and when the car's A/C computer failed, we decided to swap cars and they would get it fixed while I was working and at college. Then, we would trade back the next time I was at home.
Well, the shop that replaced my A/C pointed out to my Dad that the tires were dry rotting, and suggested they be replaced because they could have failed him on the highway. I should mention that with the Bf Goodrichs, there was no shake or vibration at any speed. As a result, without telling me, my Dad had the guy put on a set of Fuzion ZRi's (same size, 225/60R16) and had them balanced. My Dad had the car for a month. The day I took the car out I noticed the shake. So I had it re-balanced. Still shakes.
Took it back to Pensacola, had it re-balanced again. Guy and this shop says the balance was way out. Not as bad, but still there.
So, other than balance, what can cause this? Alignment? Damaged wheels?
Chris_K_F drives an FR-Slow
> Vimto
08/12/2014 at 10:19 |
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Sounds like it could be a bad wheel bearing. I had a similar situation with my 2000 Corolla.
Wishin & workin for an E39 M5
> Vimto
08/12/2014 at 10:19 |
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Tie rod ends, driveshaft wobble or worn out couplings.
CalzoneGolem
> Vimto
08/12/2014 at 10:19 |
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Balance
uneven wear in tires
wheels out of true
damaged tires
damaged wheels
damaged shocks
damaged springs
worn out bushings
That might be it.
Sir_Stig: and toxic masculinity ruins the party again.
> Vimto
08/12/2014 at 10:19 |
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Sounds like they didn't balance the wheels when they replaced the tires.
Arch Duke Maxyenko, Shit Talk Extraordinaire
> Vimto
08/12/2014 at 10:20 |
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Alignment, ball joints, tie-rod ends, shitty pavement.
mr_gofast
> CalzoneGolem
08/12/2014 at 10:22 |
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mud or debris on the rim or wheel causing imblance., tie rod ends loose, loose wheel hub???
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Vimto
> CalzoneGolem
08/12/2014 at 10:23 |
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That's a good starter for ten. Thanks.
thebigbossyboss
> Vimto
08/12/2014 at 10:25 |
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Alignment. My car used to shake at highway speeds. After alignment it stopped.
Meatcoma
> Vimto
08/12/2014 at 10:25 |
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Ujoint failure, non catastrophic - SOON!
edit: although after reading more of your post and noting that it is only a 2007, I'm betting it's not ujoints.
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CalzoneGolem
> Vimto
08/12/2014 at 10:25 |
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Oh yeah alignment for sure but you mentioned that.
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CalzoneGolem
> mr_gofast
08/12/2014 at 10:27 |
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the possibilities are endless!
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Vimto
> Meatcoma
08/12/2014 at 10:28 |
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This car has had a pretty easy life. It was owned by an old man in Orlando for 7 years before I bought it, and I don't beat on it.
DoYouEvenShift
> Vimto
08/12/2014 at 10:31 |
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Defect in one of the new tires maybe. Or whoever is balancing them isnt very good at it. Bent wheel could also cause this. Driveshaft out if balance maybe.
However, since it started with the new tires, and they've been balanced repeatedly already. Im gonna say probably a bad new tire. Do you feel the whole car shaking or mostly the steering wheel? Did he buy them from a national chain type place? Take the car to them and tell them you suspect a bad tire. It happens, nobodys fault really. You could also ask for a roadforce balance. Those machines will tell the operator if the runout is too great and will suggest a new tire. Good luck.
M54B30
> Vimto
08/12/2014 at 10:35 |
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could your driveshaft be out of balance? I had to get a driveshaft on a Grand Cherokee rebalanced, hard to find shops that can do it
Takuro Spirit
> Vimto
08/12/2014 at 10:40 |
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Could be a u-joint or a bent driveshaft.
I would suspect the cheap tires though. Have them Road Force balanced if they haven't been already. That's the best way to rule them out.
You can tell a Finn but you can't tell him much
> Vimto
08/12/2014 at 13:27 |
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It could be wheel/tire related or it could be driveline related. Or you could have a little bit of both going on. IIRC the vibrations at the lower end of that speed are commonly associated with driveline problems (U-joints, CV joints, driveshaft imbalance) and speeds at the higher end of your range are associated with wheel/tire imbalances (weight imbalance, out of round, soft spot on tire).
MotoIQ has a pretty interesting read on speed dependent wheel vibrations. It is worth reading the whole article and there is probably some good information in the comments too.
The short answer, Eric says in typical-engineer fashion, "If there is a significant imperfection in a rotating wheel assembly, it can be amplified when the wheel's rotational frequency coincides with the "wheel hop" resonant frequency of the unsprung mass, which naturally occurs at highway speeds."
Let's start the Engineer to English translation with the first part of that. If there are once-per-cycle imperfections, such as a mass (weight) imbalance, out-of-roundness or a variation in the stiffness in parts of the rotating wheel assembly (tire, wheel, hub and/or brake rotor), rotating forces (often called "Road Forces") can be produced at the same frequency as rotation, with amplitudes relative to the imperfections. Eric continues, "At highway driving speeds the rotational frequency can coincide with the first natural frequency of the unsprung mass, causing resonance or amplification of the vertical component of the rotating force and potentially producing what is called a wheel hop."
As for the old tires getting replaced, that was the right thing to do. Tires have a shelf life, especially if they are outdoors and exposed to UV light.
Jedidiah
> Vimto
08/12/2014 at 15:18 |
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Sounds like bad wheel bearings if you can feel the shake in the steering wheel.
When it starts to shake, drive along with your foot lightly on brake and gas at the same time.
If it smooths out, then you know your wheel bearings are bad.