FYI - Large wheel clearance and upper wishbone orientation
Posted: 22 Aug 2006, 23:41
Extracted from Syncro-Doublecabs forum
I would imagine that whilst castor can be corrected on the radius arm bush positioning nuts, king-pin inclination angle and possibly scrub-radius might be affected by this. Main thing si they're the same either side though!
Kudos to Dennis Haynes for putting his finger on why I'm not having front tire clearance issues on the current van, unlike my last.
Dennis mentioned that the upper control arms can be installed 'backwards'. One arm fits either side, BUT the mounting for the upper ball joint is off center by around 3/4 inch. So you can install the arms with offsets forward or rearward.
Rearward puts the centre of the ball joint close to the shock bolt, forwards is well ahead of it.
Dennis said that his initial setting of the drag link for correct castor is about 11 threads up for the nut. I have a couple of threads showing, and the upper arms are both offset towards the front.
So the whole setup is biased forwards almost 1.5 inches forward, which is pretty much what my fender lip clearance is on this van. I'm guessing this was a factory setup since both sides look untouched from new (ie rusted in place now) I looked in Bentley and didn't see any mention of which way to install the upper arms, but I suspect mine are incorrectly done.
However it looks like the castor setting was done properly. So I'm happy with this abundant clearance for big tires.
Since the arms are symmetric top-bottom, and are intended to used either way up, depending on which side they are on, I can't see a problem with this installation. So I'm keeping it this way, and anyone contemplating putting big tires on may want to set the arms up with the offsets forward and redo the castor/drag link. I can't see any problems with this setup, but any advice is welcome.
So skip measuring the drag link like I suggested, just peek over your tire and see if the ball joint is ahead or in line with the shock bolt.
Tx again Dennis, Tim
I would imagine that whilst castor can be corrected on the radius arm bush positioning nuts, king-pin inclination angle and possibly scrub-radius might be affected by this. Main thing si they're the same either side though!