Hi,
anyone have any suggestions as to how I can accurately check the castor angle? Cheers
Jon

Realistically, you will neeed a full alignment system to do it accurately, a good guide is http://www.locostbuilders.co.uk/viewthread.php?tid=17148

I thought it would be the old string technique. I feel better knowing someone else has used it to good effect. What is the effect on the handling if it ends up being miles out? I guess the only cure is to reposition the wishbone mountings.

I made my wishbones with 22mm setback, checked my pickup points with a laser jig at work and all was spot on.

I put the car on the Hunter alignment system, and came up with 3°55' on the LH and 4°15' on the RH. I should have ended up with 5°30' but I think that the bushes settle after driving, brake testing (SEVERE!!) etc. The self centring is fine and could dislocate a careless thumb at speed. The Cortina in its natural state has only 1°30' of castor, and I have only heard of self centring complaints from builders using Sierra uprights, Perhaps Uncle Rons drawings were not that far out for the upper wishbones after all?

I found using an inclinometer very usefull. It allows you to position and clamp the suspension brackets whilst taking a castor reading.

The inclinometer is rested against 2 equal length strips of ali that are drilled so they sandwitch between the upright and the balljoint nuts.



Castor Angle Measurement

Make sure the camber and tracking is set before taking measurements.

[Edited on 14/4/05 by GaryM]

Maybe this is why mine seems miles out. I haven't set the tracking or camber yet. This is all new to me! If the castor is out what is the result? I imagine it might make steering heavier and bugger up the self centering.
I was checking the castor in much the same way as the photo with the inclinometer but using a spirit level and I was about 10mm away from the required 22mm. I suppose I should set everything else up first. The last thing I want to do is to have to move my brackets. Any thoughts/opinions most welcome.
Cheers
Jon

I wanted to have my wishbone brackets positioned centrally on the chassis tubes so I had some top wishbones fabricated with a greater rearward offset to get the required castor.

Providing you've got the clearance (around your shock) you could try this if you find you've got insufficent castor.