Matth93
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| posted on 23/2/17 at 06:35 PM |
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I have just copied this from the MK build manual.
Changing the camber you should only screw the top ball joint in/out of the wishbone and keep the mushroom in the SAME location each time. The
mushroom is there to adjust castor and should normally be set such that the top of the ball joint is as far forward as possible.
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Camber Dave
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| posted on 23/2/17 at 07:11 PM |
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quote:
Originally posted by Matth93
The hole that the ball joint bolts into on the mushroom should be as far forward as you can get it (so leaning the top of the hub backwards) to give
you some castor although on my car it doesn't give enough to get self centering on the steering
It is quite correct to arrange the most offset between the wheel centre and the hubs's axis of rotation does give some castor.
However unless the upper ball joint is 3 to 5 degrees behind the lower one insufficient caster will result.
I had this problem on a Dax Rush about 10 years ago. The Dax manual also quoted the same as the MK
However the castor gauge showed the truth. New top arms fixed it and gave the owner stability and confidence.
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SJ
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| posted on 24/2/17 at 07:57 AM |
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IIRC The mushroom doesn't change castor as moving it doesn't change the position of the top ball joint in relation to the bottom. Castor
angle is the variation from vertical of a straight line drawn through the centre of the top and bottom joints.
I modified my top wishbones by putting rose joints on instead of poly bushes to allow the wishbone and therefore top ball joint to be moved
backwards.
This does make the steering much better and increases feel, though even with around 7.5 degrees of castor self centring is still fairly weak on the
Indy.
Not sure why - several people have said this is is due to chassis flex which could be right. Personally I think there are probably also other geometry
issues in play but not sure what. The car self centres great when going backwards!
Either way the rose joint mod is a fairly easy and cheap mod to do and improves the steering feel a lot.
Stu
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MikeRJ
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| posted on 24/2/17 at 01:23 PM |
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quote:
Originally posted by SJ
IIRC The mushroom doesn't change castor as moving it doesn't change the position of the top ball joint in relation to the bottom. Castor
angle is the variation from vertical of a straight line drawn through the centre of the top and bottom joints.
Correct, it does not change the castor angle as this is fixed by the ball joint centres. However it does allow a small change in trail (distance
between tyre contact patch and steering axis centre) by effectively moving the wheel back or forward, and trail also helps with self-centring.
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SteveWallace
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| posted on 24/2/17 at 05:01 PM |
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quote:
Originally posted by flanders
anyone got a picture of the secondary bolt fitted?
This is mine just pre-IVA. The silver looking round thing just below the mushroom is the allen key headed bolt that I used.
[img]
 
Description
[/img]
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flanders
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| posted on 24/2/17 at 05:51 PM |
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Ah ok I get it! So just drill right through the. Upright and the mushroom, the I take it there a locknut on the other end of the bolt inside the
upright?
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SteveWallace
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| posted on 24/2/17 at 08:51 PM |
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That's right. There's a nyloc on the other end of the bolt. A bit fiddly to get on but it went through IVA without comment.
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