Section : Wheels and Tyres

Chronic vibration at speed

Posted By : Paul Hewitson, 19-Jan-2007, 01:39pm

• Chronic vibration at speed

  Posted By : Mark Astley, 19-Jan-2007, 04:36pm

  Hi Paul,
  
  I would think that a flat spot on what should be a round brake disc could well give you the vibration as it would not rotate smoothly, as to the wheel balancing, I don't know of anyone myself, but you could ring Sports Car Supplies at Whickam and ask who they use.
  I know Mark Ramsey at vehicle services in Chester-Le-Street recently fitted wires to his vitesse, he changed the tyres so must have had them balanced somewhere local to him.
  Give me a shout if you want numbers and I'll pass them on to you.
  Yours
  Mark
  

• Chronic vibration at speed

  Posted By : Michael Charlton, 19-Jan-2007, 05:40pm

  Hi
  
  I have : a MK3
  wire wheels
  
  First of all any good tyre fitter can balance wire wheels it doe not need a special fitter/balancer , so long as he has the centre locater fitter into the wire hub then he should be ok.
  Ive had a few sets of tyres fittted and the wheels re balanced with no problems
  Went to Le Mans Classic and around the track at speed with no problems
  How old are the wheels and splines?
  Are they knock ons? or bolt ons?
  If knock on s read further
  The splines can get worn and give misalignment
  It has been known with worn splines to allow the wheel to then rotate on the splines if they are worn and the knock on spinner can loosen and the wheel drops off
  Now, if the previous owner allowed this to happen and the wheel drops off , where does the front end land??
  On the disc does it not , and when one brakes when the wheel drops off........you get a flattened edge after skating down the road
  Does that shake the old grey cells?
  
  Mike
  Syks

  • Chronic vibration at speed

    Posted By : Paul Hewitson, 20-Jan-2007, 07:06am

    Mike,
    
    The wheels are knock on, I have heard the horror stories about the vagaries of the splined hubs and I guess that the scenario you just described would account for the flattened spot on the brake disc.
    
    I have no idea how old the wheels/hubs are, the wires are in pretty shabby condition but when I was working on the wheel bearings the fit between the wheel and the hub felt pretty firm (although I have nothing to compare it to). I guess that this leaves me with two questions
    -> how can I tell whether the splines are overly worn (other than by waiting for the wheel and car to part company) i.e. is there a prescribed depth that the spline should be?
    -> if the scenario you paint is a goer then, aside from replacing said misshapen brake disc, is there anything else that I need to have a look at?
    
    Cheers
    
    Paul

    • Chronic vibration at speed

      Posted By : Anthony Davey, 20-Jan-2007, 10:45am

      Hi, As other people have said my first point of call would be to try and get them balanced, and watch them do it for this reason. If the spokes have not been adjusted correctly or have been alowed to slightly distort you will find that what appears to be a perfectly serviceable wheel will need excessive wheel weights to balance them or will not balance at all. I say watch them do it if you can as i had some bolt on wire wheels on my MKIV and suffered the same problems. All appeared to be ok when you visually inspected the wheel and tyres but what you can't see without undue danger is what the wheels are doing as you drive. The spokes had moved out of adjustment over time which is a characteristic of wire wheels especially when cornering hard, which is why older wheels need to be inspected regulary. When they were on the machine in a tyre fitters you could see the wheel centre was no longer in line with the rim on 3 out of 4 wheels, resulting in a lateral movement of 1.5" on the worst wheel as it was rotating! The end result is either send the wheels to a specialist to rebuild or probably the more cost effective option buy new ones i'm afraid. Incidently associatd with this was that the front wheel nuts would work lose over time and distorted the studs slightly which only compounded the error and was only noticeable when you rotated the hubs without wheels on. I don't mean to be the prophet of doom but if the car is still on the road get it checked as soon as.
      
      All the best
      
      Tony
      
      I also agree that the flat spot on the brake disc could well have been caused by he wheel coming off in the past and I would also check the chassis outriggers onfront and behind the wheel in question for signs of contact with the road.

    • Chronic vibration at speed

      Posted By : Chris Taylor, 20-Jan-2007, 10:49am

      As regards splines, with the wheel in the correct position but without the spinner done up, can you feel any slop in the wheel when trying to rock (in all directions), and also when trying to rotate the wheel against the hub (needs someone else to keep the brakes applied). There should be only the slightest amount of movement of the wheel.
      If there is visible distortion of a brake disc, then I would hazard a guess that that is the source of your vibration. You should always replace discs in pairs.
      Also worth getting the wheels balanced (they may have been thrown out of balance by the running with the vibration caused by the discs!) and checked for running true.

• Chronic vibration at speed

  Posted By : Michael Charlton, 20-Jan-2007, 02:04pm

  As you have said they are knock ons.
  1.The splines on the hub adaptor can wear and have round apex s
  2. The splines on the hub can also do the same
  3. There should be no movement when rotating once the knock on spinner is tight.
  4. There is also the scenario that the wheel/ hub should sit flat on the spline adaptor as there has been instances where the adaptor /nuts/studs have been the wrong size and they/one have been resticting the seating when knocked on.
  
  If you remove the wheel look and see if there is any chafe marks where the nuts holding the adaptor on sits inside the wheel hub where the spokes are laced
  
  Other than that I'm up to negotiations on some pristine second hand ones with new tyres/tubes
  
  Mike
  07788911742

  • Chronic vibration at speed

    Posted By : Steve Cureton, 21-Jan-2007, 08:58am

    It could be something as simple as a faulty tyre, check carefully for buldges and distortons all around te tyre inlcuding the inner side walls. I once had a bulge on the inner wall which was dificult to spot but it was giving me all sorts of shake and vibration problems. I eventually found by jacking up each corner in turn and getting a fixed point just clear of the tyre so I could check the gap remained constant as I slowly turned the wheel, I used a foot pump in the open position with the 'pedal' almost touching the tyre. I hope that makes sense, hard to describe meaningfully.

    • Chronic vibration at speed

      Posted By : Paul Hewitson, 24-Jan-2007, 06:02pm

      Guys,
      
      Thanks for all the help. I took said wheels to local tyre bay who reckoned he could balance them and two out of the three he looked at (I was short on time so got the spare and the front pair checked) were distorted - one badly so, the other servicable. He rebalanced the good and not-so-knackered one and the vibrations have calmed right down.
      
      In view of the other recs I also plan to replace the brake disc and see where that gets me, guess I will be checking everything else in that corner for any other damage.
      
      
      Cheers
      
      Paul H