So I'm designing a jig for my front suspension mounts & note that the book claims a castor angle of 5.3 degrees but the wishbones as designed give exactly half that (pointing to calculator trouble in the champion household.....)(or mine.....)
I further note that lots of folk have trouble with self centring at SVA. At last the point - what castor angle to people recommend. I apologise if this has been done to death before.....
PS I'm tempted to weld top supports back a bit and bottom supports forward a bit and make the top wishbone symmetrical - why should I not do this?
Thanks
Bob C

The book is full of errors Bob the main one being the placement of uprights FU1 and FU2 (rightly named ) which affects castor angle these have to be resited and the top brackets moved backwards, go to www.mcsorley.net where you'll find the info you need and a true cutting list etc.
Hope this helps.
Cheers,
Bob

or you could make your wishbones castor adjustable....
see my pics to see how i have done mine.
Tim

Isn't the castor in the book 5.5 degrees? I'd read it as 5'30", or 5 degrees 30 seconds. Too late for me now if I'm wrong .

In North America we have to use a different donor and custom wishbones so we don't get bit by this error. I'm pretty sure there's a very long thread on it here with some good tips on setting up the brackets and FU1 & 2.

One problem with moving FU1 and FU2 is you would also have to change the angle of the L 'assembly', unless you redesigned the wishbone.

Another possible option would be to simply change the design of the top wishbone, to give you the correct castor angle and make it fit the chassis as in the book. I.e. make it more offset. This is what i plan to do when i build. (Or can you not do this? Will it foul the dampers?)

There is a drawing of this design on my website. (see signature) Though you people who have built will probably see something wrong with the way i would do it!

Cheers

I changed the design of the upper wishbone to compensate for uncle rons bad maths

image attached
Rescued attachment Wisbone Modification.JPG

I also changed angle of top wishbone, using straight, not curved tubes. Didn't foul anything.

Excellent - I'm not going soft then! So we agree that 5.5degrees is a suitable castor angle?
Cheers
Bob

Bob,
One thing to remember for SVA time is that adding a bit of extra toe-out will amplify whatever self-centering you already have so if the examiner is not happy then bear this in mind. Ideally set it up before the test to have enough self-centering, you can worry about proper wheel alignment after the test.

By the way, my solution to the problem was to attach my mounting brackets farther back on FU1 and 2 and then do the same on LA and LB at the front. This left the upper top tube hanging off the tube a bit too much but this was solved by doubling up the chassis tube across the overhang. I could have altered the angle of the front assembly but this would have not given me enough engine bay length for the Rover V8 engine.

Cheers,
Craig.