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Thread: Tyre wear/wobbles/bump steer :(

  1. #1
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    Tyre wear/wobbles/bump steer :(

    Hey folks,

    I have my front left tyre wearing out on the outside edge of the tyre much more than the inside. I also have considerable bump steer/wobbles when i hit bumps on the bitumen.

    I have always had a tiny bit of bump steer as i have a small lift and taller tyres. As such i am fitting corrected caster bushes soon.

    However the new problem with tyre wear and wobbling crazy bump steer and the car kind of feels like it wants to drift all over the road is totally new.

    I have a pretty new steering dampener. Prying the bushes on the panhard rod and radius arms results in no excessive movement (in my opinion).

    Steering rod balljoints are all reasonably new (heavy duty steering arms). The wheel alignment seems ok - not sure if wheel alignment would result in wear on only one edge of the tyre anyway.

    I read an old thread or so on the forum about the wrong preload on swivel hub bearings could be the cause. I could check the bearing preload again but I did check for play in the hub by trying to rock the wheel back and forth and there is not movement left or right or up/down.

    With this pattern of tyre wear presumably the problem is just the camber? If so, what could be wrong with the swivel hub that results is such excessive tyre wear on the outside edge, yet results in no play when rocking wheel/hub?
    I am unsure how lack of swivel hub bearing preload (slightly worn bearings) could the extent cause these kind of problems - after all the hub is connected with a couple of steering arms to keep it from unwanted movements...

    Thanks for any opinions!
    97 Disco 300Tdi, front & rear diff locked, hybrid turbo, full width intercooler, cranked front & rear arms,
    2” dobinson coils, terrafirma shocks, HD steering arms, diff guards, rocksliders, domin8r winch, tank guard

  2. #2
    Judo's Avatar
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    Possibly more than 1 issue at play but the bump steer does sound like swivel preload to me. You can’t check it by rocking the wheel though. You’re checking for play in the wheel bearings by doing that.

    The workshop manual has the procedure and it exists in a few threads on here too (do a search), but it’s something like jack up wheel and use a stand, remove wheel, remove steering rod and drag link. Check how easily the hub swivels. (You’ll have to search for the correct setting). Adjust by removing shims at the top of the hub assembly.
    - Justin

    '95 Disco 300TDI - sold
    '86 County 110 Isuzu
    2006 Range Rover Vogue td6

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    JDNSW's Avatar
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    The tyre wear suggests incorrect toeout. The wobbles are almost certainly free play somewhere in the steering or supension. Two checks.

    Firstly, get someone to saw the steering vigorously back and forth while you check by vision and feel for any free play in the steering and front suspension. Look at the steering box anchorage, the pitman arm to pitman shaft, all tie rod ends, both ends of the panhard rod, both swivels, and both chassis and axle bushes on the radius arms.

    There should be no movement anywhere, except slight compression of rubber, and definitely no clicking anywhere.

    Secondly, jack up each front wheel, and see if you can move it either vertically or horizontally by grasping each side (and then top and bottom) of the tyre and rocking it. There should be no movement with the steering locked. If there is, work out where it is - if it stops with someone's foot on the brake, it is a wheel bearing, if it is only in the vertical attempt, it is swivels.

    Note that there is almost certainly more than one source of free play. Most likely to be the main culprit are the panhard rod bushes or tierod ends, but there are plenty of other places that can contribute!
    John

    JDNSW
    1986 110 County 3.9 diesel
    1970 2a 109 2.25 petrol

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    Quote Originally Posted by JDNSW View Post
    The tyre wear suggests incorrect toeout.
    Thanks guys!

    Wouldn't it be too much toe-in causing wear to the outside edges of the tyre?



    Anyone know what the correct toe-in degrees/mm difference between front and back is meant to be? Something i can measure with a tape measure...
    My workshop manual says "X-Y= 0 to 2mm" with x front measurement between tyres and y back measurement between tyres.
    But 0 would mean no toe-in and 2mm would mean slightly toe-out... :/
    97 Disco 300Tdi, front & rear diff locked, hybrid turbo, full width intercooler, cranked front & rear arms,
    2” dobinson coils, terrafirma shocks, HD steering arms, diff guards, rocksliders, domin8r winch, tank guard

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    Easy thing to check is actual wheel bearings.
    Mine seem to get slightly loose every few months(haven't logged them, but maybe 6 months/15K klms). I've marked the last one I did recently and keep an eye on when it'll need checking.
    Easiest job to do compared to the other possible issues likely causing the wobble.

    I did my swivel preload a while back, total PITA of a job in reality. idiotic brake pipe location, mine has oil in hubs, so messy job. Swivel bearings looked good(I actually did it for both preload check and to check the condition of the bearings swivel pin).

    If you have a hub nut socket, a quick check of wheel bearing nut tightness could eliminate some steering kickback, if they're a tad worn.

    When you say " ... I could check bearing preload again... "?
    Do you mean, wheel or swivel?
    What could be wrong is worn swivel bearing/s and/or pin.

    One other thing I noted not mentioned is the steering shaft.
    For the past 2 years, I've been meaning to pull mine and give it a check over, maybe a clean up, grease/lube if possible .. but they can wear(unit and or rubber coupling) check splines and bolt that secures it.
    Play in the steering shaft seems to be magnified 100x through the steering wheel when it comes to a bit of kick back.
    Arthur.

    '99 D1 300Tdi Auto
    '03 D2 Td5 Auto

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    JDNSW's Avatar
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    If it is the same as the 110, and since the geometry is the same, I'm sure it is, toe out is what it is supposed to be. Most cars have toe in, which means wheel alignment specialists have been known to apply toe in rather than out. And, in the not impossible situation of a slightly bent axle housing, the toe out needed to prevent uneven tyre wear will be different, probably more toe out.

    Note that measuring toe out or in is a complete waste of time if there is any free play in the tie rods ends on the track rod, wheel bearings, or swivels. (And care is needed if the wheels are bent)
    John

    JDNSW
    1986 110 County 3.9 diesel
    1970 2a 109 2.25 petrol

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    Quote Originally Posted by AK83 View Post
    When you say " ... I could check bearing preload again... "?
    Do you mean, wheel or swivel?
    Thanks.
    Yep, I set the swivel hub bearing pre-load about 50,000kms ago.
    The steering and tyre wear have been ok for about 12 months, but it has taken a few hits offroading in that time so something has changed in the suspension/steering.

    Anyone know if an adjustable panhard rod is worth it for only a 2 inch lift?

    I have checked for play in the tierod ends (pretty new), panhard bushes, radius arm bushes etc - all seems ok. As i mentioned i am replacing the radius arm bushes soon anyway.
    97 Disco 300Tdi, front & rear diff locked, hybrid turbo, full width intercooler, cranked front & rear arms,
    2” dobinson coils, terrafirma shocks, HD steering arms, diff guards, rocksliders, domin8r winch, tank guard

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    Quote Originally Posted by JDNSW View Post
    If there is, work out where it is - if it stops with someone's foot on the brake, it is a wheel bearing, if it is only in the vertical attempt, it is swivels.
    Awesome, great tip! I will try the brake test tonight and see if the swivel bearings are at fault.
    97 Disco 300Tdi, front & rear diff locked, hybrid turbo, full width intercooler, cranked front & rear arms,
    2” dobinson coils, terrafirma shocks, HD steering arms, diff guards, rocksliders, domin8r winch, tank guard

  9. #9
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    Okey dokey.

    So i checked for play in the wheel bearings and swivel hub bearings and there is only a tiny amount in the wheel bearings that i will sort out soon.

    I also checked for play in the steering joints, arms, mounts etc. Also, checked the toe-out/in and it is set as approx 0.

    The only thing i haven't checked yet is the swivel hub preload.

    On thinking about the problem i removed the front left shock absorber to see if it works and it is stuffed!! No resistance to compression and a really slow expansion/rebound.

    So my next question is: If we assume that tyre wear was caused by incorrect wheel alignment... how much bumpsteer/wobbliness can not having a shock absorber at one side on the front cause?
    97 Disco 300Tdi, front & rear diff locked, hybrid turbo, full width intercooler, cranked front & rear arms,
    2” dobinson coils, terrafirma shocks, HD steering arms, diff guards, rocksliders, domin8r winch, tank guard

  10. #10
    JDNSW's Avatar
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    Quite a bit I would think, although I am not sure about the wobbles, unless these are not the usual wobbles, which are sideways, where lack of a shock would lead to vertical wobbles - which may feel much the same from the driver's seat.
    John

    JDNSW
    1986 110 County 3.9 diesel
    1970 2a 109 2.25 petrol

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