Chippy
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| posted on 3/9/06 at 09:17 PM |
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Offset Sierra Bobbins??????????
Hi All, something that I don't understand about these offset bobbins/inserts. The angle of the caster is through the two pivot points,
("ie" bottom balljoint, and top balljoint). If you mount these in an offset what diference does it make, as I see it the two pivots stay
in exactly the same place, so the caster would be the same. Maybe somebody clever can tell me why they work, (if they work), as I can't see that
they would.  "Confused" Thanks Ray.
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StevieB
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| posted on 3/9/06 at 09:22 PM |
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Surely if you change from the offset searest the front to being nearest the rear, you change the pivot centre for the wheel in relation to the centre
line of the top/bottom ball joint?
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DIY Si
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| posted on 3/9/06 at 09:26 PM |
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Makes bu88er all difference. You need to move the ball joint itsef, rather than were it attaches.
“Let your plans be dark and as impenetratable as night, and when you move, fall like a thunderbolt.”
Sun Tzu, The Art of War
My new blog: http://spritecave.blogspot.co.uk/
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StevieB
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| posted on 3/9/06 at 09:30 PM |
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It has to make a difference - if you move something, it has an effect. It might be a negligible effect that you wouldn't notice though
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mookaloid
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| posted on 3/9/06 at 09:36 PM |
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it does make a difference - just think how supermarket trolley wheels work, or motorbike front wheels.
I agree the castor angle (the line between the ball joints) doesn't change but StevieB has it, moving the axle in relation to the line has an
effect.
Actually if you put a castor gauge on the car and then change the position of the insert then the castor gauge reads differently, I have not seen this
myself but I was told this very recently by someone who sets up cars professionally.
I know this is a contentious issue but I would suggest that anyone who is in doubt actually tries it to see.
HTH
Mark
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DIY Si
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| posted on 3/9/06 at 09:37 PM |
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Moving it can affect the cmaber as it will tip the upright in/out, but castor is the angle between the joints themselves, not where they attach to the
hub. To alter castor you have to alter one or both of the wishbones in some way.
“Let your plans be dark and as impenetratable as night, and when you move, fall like a thunderbolt.”
Sun Tzu, The Art of War
My new blog: http://spritecave.blogspot.co.uk/
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StevieB
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| posted on 3/9/06 at 09:39 PM |
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I quoted the MK build manual in saying castor/camber because I can never remember which is which.
Way to pick fine points!
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DIY Si
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| posted on 3/9/06 at 09:42 PM |
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Camber's in/out, castor is forwards/backwards. Well, that's how I remember it anyway. Easy to confuse stuff like this, as generally, once
it's set you can forget about it!
“Let your plans be dark and as impenetratable as night, and when you move, fall like a thunderbolt.”
Sun Tzu, The Art of War
My new blog: http://spritecave.blogspot.co.uk/
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StevieB
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| posted on 3/9/06 at 09:45 PM |
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The way I see it - my mushroom caps were such a tight fit, they're staying where they are!
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Guinness
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| posted on 3/9/06 at 10:11 PM |
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This has been discussed a couple of times before. I don't really understand it myself, even having followed the threads. I think I'd
have to understand more about suspension geometry first, but here is the link
http://www.locostbuilders.co.uk/viewthread.php?tid=20700&page=3
Rorty attached an cad sketch showing the effect of rotating the mushroom insert on the end of the axle.
HTH
Mike
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