Rear toe in - excessive at 12-15mm

Discussion in 'Steering, brakes & Suspension' started by steve_4802, Dec 11, 2016.

  1. steve_4802

    steve_4802 Active Member

    Messages:
    269
    Location:
    Sunshine Coast
    Hi team,
    My rear end has excessive toe in, with a difference of nearly 15mm between the front and rear of the tyres. I've checked myself with a tape and also had a professional measurement with lasers a while back, and my go to mechanic was the one who flagged the problem with a simple measurement originally.

    I haven't really started working on the back end so not very familiar with it all yet, but I wanted to see if anyone had any ideas what it might be and more importantly, how I can rectify it.

    I'm told I'm beyond the limits of normal adjustment and it can't easily be brought back into alignment. The result is accelerated tyre wear (but still getting about 40k kms) and the safety risk of reduced traction at the back-end.

    What could be the problem? Could the diagonal arms be slightly bent, I'm told this could be part of it and that it's worth flipping them from one side to the other to see? Alternatively, could it be related to the fact that the car is lowered by about 50mm? It's just been lowered the usual way be resetting the splines on the rear torsion arms. It's worth noting as well that I do have fairly large amounts of camber, not sure if this is a hint?

    Love to hear anyone's thoughts on this one.
     
  2. Barry

    Barry Well-Known Member

    Messages:
    2,336
    Location:
    Abbotsford NSW
    That would be my guess
    I have heard of it happening before
     
  3. cbus

    cbus Well-Known Member

    Messages:
    10,639
    Location:
    sunshine coast
    Plenty of toe adjustment in rear and it should be close to zero( cant remember exact number?
    Between zero and 1 mm in.
    Will handle like crap on corners?
    Camber adjustment is limited.
     
  4. steve_4802

    steve_4802 Active Member

    Messages:
    269
    Location:
    Sunshine Coast
    cbus, I'm already at the end of the spring plate slots. Is there anything else that can be adjusted or would I need to resign to shims to straighten from there?
     
    Last edited: Dec 11, 2016
  5. David H

    David H Well-Known Member

    Messages:
    2,847
    Location:
    newcastle
    Mmm. Pivot in a circle. Toe in shouldn't move that much with lowering. Same pivot. If radius arms bent 'side swap' may decide what has happened. I'm thinking something on the outside/ end of pivot. Post torsion arms. That just leaves wheel bearings/end arm pivots but doesn't account for 15mm. Consistent both sides or just one.? Prior accident? Chassis? Torsion bar outer carrier?
    Just guessing!
    Had a Datsun 240z that had elogated holes in its A arm lower bolt position. Used to randomly adjust camber going into corners! Was an interesting drive!
    David H
     
    Last edited: Dec 12, 2016
  6. steve_4802

    steve_4802 Active Member

    Messages:
    269
    Location:
    Sunshine Coast
    Hi David,
    It's about 7mm each side (so 15mm when measuring across both sides together.)

    More clearly, for each side the difference between offset at front and rear of tyre is 7mm. Toe in
     
  7. cbus

    cbus Well-Known Member

    Messages:
    10,639
    Location:
    sunshine coast
    Sounds strange.
    When I dropped 23mm rear ( 1 outer spline) I bolted to same position and toe hadnt changed when checked on aligner.
    Cant suggest why yours is at max.
    Maybe just pull torsion cover for quick look at rubbers or bring up a notch on the outside spline and check inner as well if you have a gain on front and 23mm raise on rear is in order.
    Check the ones on arm.
    Bends in arms causing excess camber are very difficult to detect unless removed but someone may have a suggestion for checking in situ other than the camber readings.
    Cant sus lack of adjustment.
    Those with more experience of big drops may have an answer.

    I would expect camber is near 3 degree both sides?
    Such would be compensated for with a few mm of toe to reduce wear but plucking a number I would only
    expect 1-3. Pure guess.

    Will think on it but nothing obvious comes to mind.
    Think there was a change from early to late in spring plates.
    Maybe someone has done a swap??
     
  8. steve_4802

    steve_4802 Active Member

    Messages:
    269
    Location:
    Sunshine Coast
    Further thinking possibilities on the train to work. If the spring plate was sitting too far in on the torsion bar that would also cause excessive toe in, right? Say, if there was a washer or something missing. In looking at the exploded view there seems to a bush inside the spring plate. Hypothetically, if this was about 2mm too thin it would explain about the amount of toe in I'm seeing I reckon? Similarly, I see the spring plate has tubular extensions each side to interface with the spline of the torsion bar, say about 1 inch each side looking at the exploded view. Is the spline plate centred on this tube such that the inner and outer extension is the same, and if not, is it possible the spline plates have been put on the wrong sides?

    Just throwing ideas out there. As there is excessive camber too, it kind of seems possible that the forward end of the spring plate could be the problem. If it was too far in that would explain the excess toe in and camber. If nothing is amiss, I'm also thinking this could be the tidiest and neatest way to shim it too, with perhaps a washer at the inside of the spline plate where attached to the torsion bar. Of course, I'd rather identify the cause of the problem than resort immediately to shims.
     
  9. steve_4802

    steve_4802 Active Member

    Messages:
    269
    Location:
    Sunshine Coast
    Some good point there cbus, thanks.
     
  10. cbus

    cbus Well-Known Member

    Messages:
    10,639
    Location:
    sunshine coast
    Im no expert but it seems very basic.
    Assume in / out set of springplate is limited by length of spline.
    Wouldnt be mucking with shims there.
    Rooted rubbers on torsion could cause problems as they centre the spring plate.
    Well worth replacing regardless as very cheap.

    Dont know if the slots are such that the plates could be swapped either side .
    Or if so that it would make a difference in settings/ adjustments.

    Camber does change radicaly with lowering.
    Meant to be a method of twisting arm to get some adjustment but havent tried it .
     
  11. steve_4802

    steve_4802 Active Member

    Messages:
    269
    Location:
    Sunshine Coast
    I think you may have guessed right cbus. I redid the back end to lift it a little and did a diy wheel alignment today to see how it all ended up.

    I replaced the spring plate inner and outer bushings while in there. Wheel alignment shows it's bang on now and within tolerance. Bearing housing is in most forward position which gives right alignment for me.

    The old bushings looked to be in good shape, but my best guess would be that perhaps they were over tightened by the cover plate pushing them a bit too far in. Nothing else I can see that might have caused my excessive toe in.

    Anyway, glad it's all where it should be now. Safer and can look forward to less tyre wear.
     

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