Balance a tyre at full speed ?

Discussion in 'Wheels, Tyres, Brakes & Suspension' started by maxima, Apr 14, 2014.

  1. maxima

    maxima Hardcore MB Enthusiast

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    10 yrs ago I was told by 2 shops (one of them being MB franchise) that they do not balance wheels past 70 mph..

    Now I am back to the square one contemplating new tyres..

    Obviously performance tyres have all sorts of speed indexes up to 300 kmh..

    Could you guys tell - whats the situation these days? Are there shops willing to balance tyres at speeds over 120 mph? Do they have capable equipment for that?
     
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  2. st13phil

    st13phil MB Club Veteran

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    The balance of a wheel does not vary with speed, only the out of balance force varies - with the square of the speed.

    There's no reason why a competent operator with a properly maintained and calibrated balancer can't balance a wheel well enough that the residual out of balance force at (say) 150mph would not be a problem.
     
  3. OP
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    maxima

    maxima Hardcore MB Enthusiast

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    ok.. but then why some tyres vibrate at specific speeds and dont vibrate at other speeds?? I had that quite a few times in my life..
     
  4. C43AMG

    C43AMG MB Club Veteran

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  5. V12

    V12 MB Club Veteran

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    Because they haven't been balanced properly.
     
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  6. DSM10000

    DSM10000 Hardcore MB Enthusiast

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    You are not looking at the whole picture though.

    A wheel and tyre may be balanced but there are a lot of other components to which they are attached such as suspension arms subframes etc. These will have have different frequencies at which they, individually or as a system will vibrate and this will be speed and road surface dependant.
     
  7. OP
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    maxima

    maxima Hardcore MB Enthusiast

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    yes. this is one way to see the things. they called it metaphysics 2500 years back.

    the other way to see this is that - there is a particular tyre which makes a wheel out of the balance and vibrates on speed around 80-90. Whatever place whatever rim whatever balancing machine.

    One might go back to fundamental phylosophy works asking why do we exist. How do we know if the tyre exists. What is tyre. What vibrates - tyre or the world around the tyre.. I quite understand all of that and more..

    What I dont understand why the bloody balancing machine cant be rolled to the 80 mph to see if it will vibrate.. Who was that idiot who made that limitation and made the garages and/or (?) the machines manufacturers to obey this crap..

    Just for you to understand - I had 16 cars in my life and made hundreds of thousands miles on the roads of very different quality often in physically and emotionally taxing conditions. I dont need Greeks to tell you when the wheel is out of the balance. We didnt have wikipedia back then. You either know what you do or you dont. Now everyone who is literate can think that he knows something being read it on the internet.. Yeah..

    God bless Ancient Greeks anyway.
     
    Last edited: Apr 14, 2014
  8. ARTiSAN

    ARTiSAN Member

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    I've had this happen a couple of times where a wheel starts to vibrate on the car at a particular high speed. Taking it back and getting it rebalanced (or going to a better workshop) always cured the problem.

    Re running the machine at much higher speeds may be a safety issue. I don't know that for fact but I could well imagine health and safety having an impact.
     
    Last edited: Apr 14, 2014
  9. Aoraki

    Aoraki Hardcore MB Enthusiast

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    Why spin the wheel to 120mph when it can be balanced at 5 or 10mph? As has been said previously, it's the competence of operator and quality of machine.
     
  10. hotrodder

    hotrodder Hardcore MB Enthusiast

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    Spinning the wheel and tyre faster on the balancing machine won't make any difference. Balancing machines measure the forces that result from imbalance and as was said earlier balance (or imbalance as nothing is ever perfectly balanced) doesn't change with speed. The forces that result from imbalance increase with square of speed but they do so in all directions i.e. spinning it faster doesn't make it wobble more, just faster.

    Crankshafts spin a LOT faster than the cars wheels but are only balanced at a few hundred rpm and something for a high revving racing engine doesn't necessarily need to be spun up faster than a road car crank to make it 'more balanced', it just needs to balanced to tighter tolerances.
    There are various different balancing grades which are about how much imbalance is likely to be tolerable for example... ISQ Quality Grades | G40 G16 6,3 G2,5 G1 G0,4 | Rotor Types Examples

    Hunter GSP9700 Wheel vibration Control System solves wheel vibration and tire pull problems that balancers and aligners can't fix covers various types of vibration including those outside the scope of wheel balancing kit and as said there's also operator error i.e. get the wheels balanced somewhere else
     
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  11. markjay

    markjay MB Club Veteran

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    Strange but true:

    Properly balanced wheels do not vibrate at any speed.

    Badly balanced wheels always vibrate at the same speed - around 30-50mph. The vibration will go away once this speed is exceeded.

    If your steering wheel vibrates at 120mph, wheel balancing is not the cause.

    This is what I was taught some 30 years ago, when the only way to become a car mechanic was through apprenticeship.
     
  12. Benzowner

    Benzowner Hardcore MB Enthusiast

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    We all rely on the machine at the garage and its operator to balance the wheel, this is then reattached to the car which also has many items which revolve with the wheel, the main item being the disc which we have a habit of grinding away with pads :( They must, at some time, go out of balance. I remember, when I was younger, wheels were balanced on the car, would this resolve the issue? I am not sure. As has been stated already, balance is balance whether at 1mph or 150mph, if it is not balanced correctly, higher revolutions/speed will show it more.
     
  13. cb1965

    cb1965 Banned

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    My previous car had a vibration at 60 - 70mph. Re-balanced the front wheels and it went away..... that does not fit with your theory.... so what gives?
     
  14. markjay

    markjay MB Club Veteran

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    Actually, it does.... the speed range I mentioned may need to be expanded to 50-70, I was quoting the figures from memory, and that was many years ago.... but the point is that it always happens within the same speed range. It will not show at lower speed, and it will disappear once a higher speed has been reached. And this is regardless of the speed at which the wheel was balanced.
     
  15. markjay

    markjay MB Club Veteran

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    Incidentally... that's for 'the Internet':


    'The machine spins the assembly at very high speed to determine the heaviest point, and signals the operator where and how many weights to place on the opposite side to compensate.'


    The spin is needed in order to establish the location of the heaviest point.... but its location will be exactly the same regardless of the speed at which the wheel is being rotated. The wheel just needs to be rotated fast enough to locate the spot.

    So the wheel is either balanced, or it is not.... i.e. it is not balanced for any specific speed.
     
  16. cb1965

    cb1965 Banned

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    Thinking about it 50 -70 is the only speed range I have experienced wheel balance issues over the years so you're right :thumb:
     
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  17. DSM10000

    DSM10000 Hardcore MB Enthusiast

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    And the winner for todays "Random stream of conciousness award goes to.........":D

    It has nothing to do with metaphysics but, as pointed out very ably by a nummber of members, it has everything to do with Physics:wallbash:
     

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