Are the dimensions in the book correct for the top front bones?

If they are not then where can i get a correct plan - i tried mcsorely's web site but i cant see drawings for wishbones on there, just chassis only.

ta

I made mine different to the book(first edition) because I couldn't achieve the 5 degrees castor and keep the brackets in resonable contact with the frame, they finished up at 5.125" (4.75" 3.625 (4" book dimensions in brackets, other dimensions remained as per the book.
Wimmera

The book is wrong if you want 5.5 degrees of castor.
I worked out where I wanted to mount the brackets on the chassis and then made bones to suit. The main point is that the lateral centreline of the upper ball joint should lie 20mm behind that of the lower.

Mick

I can guarantee that this design does give self centring steering, I worked it out to be 22mm setback to gine 5.5° Castor (not 5.3° as the book states, it meant 5'30" which is 5.5°)
Rescued attachment Wisbone Modification.JPG

..and how it looks in practice
Rescued attachment Castor lines.jpg

What if you wanted to fabricate these wishbones to suit the wider sierra track. Would it theoretically be possible to increase the length dimensions keeping the others the same?

Having said that i guess it would be useful to know the increased length needed to increase track width, so that it matched a Sierra IRS Rear end! Anyone know?

[Edited on 22/11/04 by ChrisS]

And to add to ChrisS question - does it change when using Sierra uprights and sierra track width?

I thought the Sierra modified upright used adjustable top hats which could change the castor?

ChrisS,

Of course, there's no reason not to keep the bush tube width the same and extend the wishbone length. It's what I've done.
Although it may be worth noting that MK make the bones wider aswell as longer. I guess this may be because the leverage on a longer bone is greater so it's maybe better to widen it too- who knows! Wouldn't matter if it was wider too though- just means you need to place FU1/2 further back (I guess!).

Andy,
I seem to remember Mark Allanson posting awhile ago that with the Sierra you wanted 25mm off-set instead of 22mm with the Cortina.

Rob,
You *can* use the MK adjustable top hats but they don't actually change castor, they change something else (KPI?) that gives the illusion of changing the castor! This was an argument awhile ago.
The problem with them is that they change other things too. I've got them and may change.

Better still is to use top hats with a centre BJ hole and then set the other things up correctly by other means.

Phew!

James