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Thread: what causes old cars to vibrate at high speeds?

  1. #1
    22B Junkie
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    Having thought it over, I think I am happiest to hang on to the golf gti.

    With this in mind I would like to cure one thing which annoys me about it, and that is the vibration I can feel at certain resonance speeds.

    I have felt it before in older less solid cars, but didnt expect it from a vw.

    I can only conclude it is down to age. Metros seem to do it regardless, but other golfs I have had have not suffered this.

    I am wondering if people know the solution.

    I am guessing that the only part which would specifically wear which could create this kind of thing are the bushings in the suspension and steering which may have perished or simply just worn out with age.

    Wiould replacing the entire lot at the front with say powerflex bushes (cheaper than originals) be likely to stop the resonance?

  2. #2
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    Alloys with flat spots in them from age and being bounced over potholes & kerbs for 10 to 15 years...

    The wheel balancer can probably give the appearance of a properly balanced wheel, but it may not be round!! (My old Peugeot suffered from this, but I didn't understand anything about cars then - only that you had to change the oil & plugs.)

    I agree that the bushes will be worn too.

  3. #3
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    the car is a P reg with 120k on it.

    it runs perfectly and I am otherwise very happy with it.

    the rims appear also to be in excellent condition, and aren't low profiles (15s) that would be taking large knocks.

    Good advice though.

    I don't see the issue though with non round alloys, surely if the balance is there, they won't impart any vibration (unless you are going over bumps or round bends where the gyroscopic effect will make the other moments of inertia more prevalent).

    This vibration occurs on straight flat motorways.

  4. #4
    22B Junkie
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    its the armco youve driven into whilst being asleep

    Bushes..
    TCA's
    Lower Balljoints.
    Suspension
    Wheel Bearings.
    Steering Rack.
    Arbs

    Check them for a start..

    Dont put powerflex on, just OEM or aftermarket parts.

    David

  5. #5
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    I would have thought the same as you regarding the balance. But then I also thought that they are balanced at relatively low speeds and only to an accuracy of something like 5 grams.

    I found a fairly major flat spot on the back of one rim on the Pug shortly before I sold it. I didn't have the wheel repaired, as it balanced up OK, and I knew I was selling it in the next week or two but I always wondered about it. I would hope that the tyres would have enough "tolerance" to take out any minor inaccuracies in wheels, but when does something like this start to be "major"?

    Another thing that caused the Pug to shake on the motorway was that it would get one wheel in the ruts caused by HGVs in the left hand lane and the other wheel just not sitting in the other rut. (Hope this makes sense) The result was that the car would "bounce" in and out of the ruts. If you moved over into the middle lane, the problem reduced substantially.

    For some reason, this isn't anywhere near as bad in the Scoob. Maybe because I drive faster and spend less time in the lane? Or maybe the Scoob suspension isn't quite as worn out, or the tyres/track etc are sufficiently wide to sit fully in the ruts.

  6. #6
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    trouble is I dont know hwo effective these checks will be when the car isnt moving at speed.

    Is it really giong to be noticable?

  7. #7
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    That's the problem with problems like that on older cars. How much do you spend on them with diminishing returns?

    Some cars are OK until they develop some annoying feature (clutch judder, brake judder, wheel vibrations or squeeky alternator belts). You start to fix it and somehow the problem never fully goes away. You put more and more money in to the car and new problems crop up or the old ones return.

    In the end you get so pissed off that you sell it and wish you'd not spent so much on it.

    Not a cheary thought but I think most have been through this scenario.

    F

  8. #8
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    Pretty much all cars I drive are quite old, and Ive never experienced any such vibrations ??

    What sort of wheels are on the car, and more importantly do they have the spigot rings to locate them onto the hubs?

    Ive seen cars fitted with alloys, where the wheel bore was larger than the hub spigot without spigot rings fitted, and it can give a very strange vibration through the car, yet nothing is felt through the steeering.

  9. #9
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    car is totally standard.

    i wanted to keep it that way.

    It was fleet car and I have receipts showing its proper maintenance regardless of cost.

    Alloys are still standard and in good condition. I recently changed the tires and had all wheels properly balanced.

  10. #10
    22B Moderator
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    but are they round? balancing doesnt tell you that.

  11. #11
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    what causes old cars to vibrate at high speeds?
    Pat's backside?

  12. #12
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    Adam, this is actually 'old car drone' it is a natural consequence of unitary construction, over time the panels attached to the monocoque develop sympathetic resonances, the way to negate the effects are to change the way in which the frequencies are propogated through out the car.

    Not easy...

    I think the best way is to 'paint' the underside of the car with bitumen type paint.

    This at least changes a substantial part of the unitary and may just be enough, if not then it is the following in the this order..

    Bonnet. [glued additional damping avoiding just a mat, singular locus points.]

    Door. [same]

    Roof. [same]

  13. #13
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    so, in english, underseal has fallen off and you need a square of sound proofing on the bonnet, door (which one?) and the roof.

  14. #14
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    Ha ha ha PMSL nice one David,

    Only mycroft could come up with all that bullsh1t instead of just saying "its an old car with wobbly bits, slap some gunk on it until it stops"
    Way more important then cars.<br /><br /><a href=\"http://www.CRCintense.com\" target=\"_blank\">www.CRCintense.com</a>

  15. #15
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    the vibrations is purely in the steering wheel, not in the body as such.

    The pannels dont rattle at all and the dash doesn't vibrate.

    It literally is like unbalanced wheels, but is only between 90 and 95mph (on my private estate), the rest of the time there is no noticable vibration in the steering.

    The bodywork and interior trim is as solid as if it were brand new.

  16. #16
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    Fill all the gaps up with expanding foam?

  17. #17
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    unbalanced brake discs

    when were they last replaced?

  18. #18
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    DW, thanx for providing an idiots translation, really appreciate that...

    But sadly too simple, the underseal may be entirely intact and a square of sound proofing is not what I said, the idea is to change the frequency, not lessen its amplitude as eventually the intrinsic frequency will overcome this and the car return to its' noisey ways...

    A simple pad will mean that instead of the panel vibrating at 120hz [the most irritating frequency] it instead will find another frequency, just as loud, just different... for the moment.

    Frequncy damping [true] is about banding.

    So if the Golf has a swage line in the door, then an additional strip along its' length is probably the best manner to effect this, it is important to take the damping right into the 'corners' of the door returns.

  19. #19
    V-Bird
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    Originally posted by Pavlo:
    unbalanced brake discs
    How does that happen?

  20. #20
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    because the brake discs are balanced from the factory in the unworn state, with those small clip in weight things. After 1000's of miles of wear they may not be balanced as they were, in the same way that tyres can become unbalanced as they wear.

    Paul

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