Wheel wobble | FerrariChat

Wheel wobble

Discussion in 'Technical Q&A' started by Nickt, Dec 29, 2007.

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  1. Nickt

    Nickt Formula 3

    Feb 24, 2006
    1,741
    Iver, Buckinghamshir
    Full Name:
    Nick T
    My clutch cable went last week on my 78 RHD 308 GT4, I replaced it no problem (albeit it took 4 hours to get the old one out!).
    While the front wheels were off I also adjusted the wheel bearings, as there was a little play.
    Took it out for a drive yesterday and I have developed an intermitant really bad wheel wobble on braking.
    Any ideas? Wheels are tight and true..
    Cheers
    Nick
     
  2. yelcab

    yelcab F1 World Champ
    Consultant

    Nov 29, 2001
    13,673
    San Carlos, CA
    Full Name:
    Mitchell Le
    If it was not there before, then it it something you did. How did you adjust the bearing? There is a specific procedure called out in the workshop manual. Do you have one?
     
  3. yelcab

    yelcab F1 World Champ
    Consultant

    Nov 29, 2001
    13,673
    San Carlos, CA
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    Mitchell Le
    I looked it up. The free play spec is 0.6mm to 1.0mm, no less. There has to be some freeplay. Taking it all out is bad.

    1. Tighten it to 25 N.M
    2. back it all out,
    3. Retighten to 15 N.M.

    Measure play to spec. If you own a Porsche 911, you should be used to feeling what a 0.1mm clearance feels like in your hand.

    Good luck.
     
  4. Nickt

    Nickt Formula 3

    Feb 24, 2006
    1,741
    Iver, Buckinghamshir
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    Nick T
    Hi Yelcap,
    I looked it up after I posted the question! I set the bearings up by feel, on 70s fords and Triumphs you simply tightened the nut up till the wheel locked, then backed it off a bit, this is how I did mt Dino's! I wish I had left it alone now, it was fine before :eek:
    Thanks for posting the info :D
     
  5. 2NA

    2NA F1 World Champ
    Consultant Owner Professional Ferrari Technician

    Dec 29, 2006
    18,221
    Twin Cities
    Full Name:
    Tim Keseluk
    Certainly double check that they're on tight (not a pretty sight if they come off).

    Even if they're set up a bit loose they shouldn't wobble on braking.

    It is possible that toe-in may be off and tie-rod ends are worn.
     
  6. fatbillybob

    fatbillybob Two Time F1 World Champ
    Consultant Owner

    Aug 10, 2002
    29,265
    socal
    go back to basics. There are many places to mess up by lack of knowlwedge and just bad luck. So take everything back down to the hub. Follow the WSM to set the bearing preload spec.. Make sure all mating surfaces are clean!!!! Reinstall rotor. Make sure all mating surfaces are clean!! Check to see that you did not cock your brake pads or disturb them upon reinstall on the rotor. Make sure that any caliper shims are in the proper place. Reinstall wheel gradually applying torque over the 5 lugs like on a head gasket not all on one lug first. I am sure you now all of this but you need to take possibilities of error out. Do you still have a problem? Only on braking not on handling w/o brakes? Sometimes when you do things like this you can displace the pads especially when worn. sometimes you can cure this woble by rebedding in the pads. But make sure you are mechanically sound before you do this. A wheel falling off is a bad thing and will make you feel really dumb!
     
  7. Glassman

    Glassman F1 World Champ
    Rossa Subscribed

    If the wheel seems to turn true, I wonder of the brake caliper could be causing some problems? You did say it wobbles when braking.
     
  8. Ed_Long

    Ed_Long Formula Junior

    Nov 11, 2003
    686
    Salem, Oregon USA
    Full Name:
    Ed Long
    Are you sure that the outer bearing is seated correctly, and not cocked or bound? My experience is the same as your, I tighten them until the rotor is bound then back them off a bit to touch but make sure that the rotor and wheel spin freely with just a little drag.
     
  9. Nickt

    Nickt Formula 3

    Feb 24, 2006
    1,741
    Iver, Buckinghamshir
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    Nick T
    I don't knoew Mate, Its all going to have to come to pieces to check out. I just wish I had left them alone :(

    Ed I agree, but from the posts in this thread it seems that these cars are more sensitive and the correct torque is required.
     
  10. Mark 308 gt4

    Mark 308 gt4 Formula Junior

    Apr 24, 2006
    285
    West London
    Full Name:
    Mark Taviner
    Hi Nick,
    Did you swap your wheels from side to side?
    Did you trap a bit of muck between the wheel and disc flange?
    Did you knock a wheel weight off of the inside of the wheel?
    Silly question but did your jack lift on the lower suspention arm on the first lift, its possible with the being so low?

    I must say I would have done the bearings old school style the same as you, in fact I have done mine about two years ago and all was fine.

    Good luck
    Mark
     
  11. Nickt

    Nickt Formula 3

    Feb 24, 2006
    1,741
    Iver, Buckinghamshir
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    Nick T
    Heh Mark,
    1) No
    2) Don't think so
    3) No
    4) Why? This worries me, as this is where I didi lift the car!
    Just ordered a dial gauge and mag mount off ebay to set them up by the book.

    Cheers
    Nick
     
  12. Kingpin328

    Kingpin328 Formula Junior

    Nov 7, 2003
    433
    Just a thought - have you checked your rotors? My front right rotor is getting thin, when warming up it warps slightly, resulting in 'wobbling' under braking.
     
  13. yelcab

    yelcab F1 World Champ
    Consultant

    Nov 29, 2001
    13,673
    San Carlos, CA
    Full Name:
    Mitchell Le

    Sorry Nick, my bad. Spec is 0.06mm to 0.1mm. I missed a zero in there somewhere. I do have dial guage and a mag base, but sending it to you is now more trouble than it's worth because you bought a set.

    Good luck. Going back to basic will help. These cars are touchy bastards, aren't they?
     
  14. Nickt

    Nickt Formula 3

    Feb 24, 2006
    1,741
    Iver, Buckinghamshir
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    Nick T
    Aren't they just!
    stripped both hubs down today and rebuilt them, changed nothing, torqued up as per manual put wheels on everything back to normal.
    I have no idea what was wrong, maybe one of the wheels was slightly out. Anyway, everything's cool except I noticed a rust spot under the paint on the drivers door. If its not one thing its something else.
     
  15. Mark 308 gt4

    Mark 308 gt4 Formula Junior

    Apr 24, 2006
    285
    West London
    Full Name:
    Mark Taviner
    I bet it was a lump of muck between the two flanges!
    Well done mate!

    bad luck with the rust, it always seems to creep back in the end. :0(
     

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