Vibration at High Speed

[cliffordl]

At speeds in excess of 70mph my car suffers from fairly alarming vibration through the steering wheel which if "driven through" does ease off. Any thoughts on the cause?
   
   Cliff.

[nikbj68]

Yes. You`re driving too fast! [:p]
   Ahem...Seriously though
   It sounds like a wheel balance issue, which simply having the wheels balanced at the local tyre centre may not cure. The answer is to have them balanced on the car, see the website of VIBRATION FREE of Bicester.
   I can`t vouch for the company, seems a bit dear to me, it was just the first site I found to illustrate the theory...

[A-Snake]

I would suggest finding a firm that has a Hunter Road Force balacing unit. This will explain the process.
   
   http://www.gsp9700.com/pub/features/intro.cfm
   
   "Road Force Measurement
   
   Road Force Measurement? is new to the automotive service industry. This new measurement identifies tire and wheel uniformity, which has been measured for years in assembly plants and manufacturing facilities. Road Force can be used to solve uniformity related tire and wheel vibrations. Tire/wheel assembly uniformity can only be measured under load.
   
   The load roller on the GSP9700 performs a computer simulated "road test". It measures the tire/wheel assembly to determine how "round" the assembly is when rolling under a load. If a tire were not exposed to the road surface, then balance would be more than sufficient. However, not all tires roll round under a load. For example, an egg-shaped tire/wheel assembly can be balanced about its axis, but an egg-shaped tire-wheel loaded against a surface would not give a smooth ride.
   
   To understand the effects of radial force variation on vibration, a model of a tire can be used. The sidewall and footprint can be understood as a collection of springs between the rim and the tire contact patch. If the "springs" are not of uniform stiffness, a varied force is exerted on the axle and causes it to move up and down as the tire rotates and flexes. This movement creates a vibration in the vehicle unrelated to balance.
   
   The GSP9700 load roller applies a force of up to 1400 pounds against the rotating tire/wheel assembly as it performs the Road Force Measurement?. The GSP9700 measures loaded radial runout of the tire/wheel assembly within 0.002". It plots data points as the component is rotated and calculates the radial first harmonic of the tire/wheel assembly and the first harmonic of wheel runout. The peak-to-peak value (Total Indicated Runout) and second, third and fourth harmonics of Road Force are also calculated and used for diagnostics. These measurements are all displayed on other screens.
   
   The measurements of loaded radial runout are converted to Road Force Measurement in pounds, kilograms or Newtons using the following equation:
   
   (Loaded Radial Runout) x (Tire Spring Rate) = Road Force Measurement"
   
   After having my wire wheels 'trued' I found a location that had the Road Force equiptment. The vibration is gone.

[Robin A Woolmer]

A very good point & worth knowing the facility exists to deal with these problems.
   
   Robin

[shep]

Is this vibration on an alloy wheel or a spoked wire wheel? If the latter, I have experienced the same problem which proved to be due to incorrect mounting or the wheel on the balancing machine. The wire wheel centre relies on the hub and spinner picking up on two separate faces. Most balancers locate the rear of the wheel with a cone on their machine, but ignore the front face on the wheel which is normally located by the taper inside the spinner. They tend to clamp the wheel using a large flat washer which is no good. I ended up sacrificing an old spinner by boring a hole through the centre, allowing the spindle on the balancing machine to pass through. The spinner then became the front location, keeping the wheel true to the spindle. Wheels then balanced up much better. If I haven't explained it well enough please let me know and I'll try to find a diagram of the fitting.

[AC Ace Bristol]

Andy
   
   You are spot on, Majority of wheel balance /tyre specialists do not know how to correctly balance a wire wheel and do not have the correct adaptor/s.
   
   Suggest any one experiencing balance problem in the UK, either visit
   MWS Wheels or contact Longstone for nearest details of nearest approved supplier / tyre specialist for correct balancing.
   
   You will notice the difference immediately. If the tyre Co you visit hasn't the correct facility don't waste your time and money, they could balance Ho, Ho, Ho! time again and again and get different results, However they would be consistant in that the wheel/s were never properly balanced and never will be, without the correct tools and expertease.
   
   Same applies in any Country, Visit a recommended wire wheel / tyre company and get the job done properly and pay for it once only.
   
   Good Luck.
   
   Keith