I'm just about to mount my suspension brackets to the chassis. I've designed a jig inspired from some fine examples in the photo archive (thanks lads).

However, in calculating the relative horizontal (when viewed from the side of the car) positions of the top and bottom wishbones to achieve a castor angle in the region of 5.5 degrees I need to be sure that I'm using the correct vertical distance between the top and bottom wishbones at the upright ends.

(I'm using book chassis and bones dimensions and intend to gusset the brackets if they end up too far off the frame rails)

I've seen some drawings that show the 5.5 degree angle measured with the bones laying parallel to each other (when viewed from the front of the car) which equates to a distance between bone ends of about 182mm.

But when using cortina uprights it would appear that the bones don't end up parallel but instead converge towards the chassis centreline implying a longer distance than 182mm?

Anyone got a (book) completed front suspension setup with 5.5 castor, who could measure the distance between two fixed points at the ends of the top and bottom wishbones for me please?

Does that make sense?

Cheers
Gary

[Edited on 16/11/04 by GaryMeades]

Rescued attachment FRONT JIG.jpg

Dougies jig plan will give abou 2°30' castor unless you modify the top wishbones. I fell into this trap, so redsigned the top bones. It worked out OK because I was unhappy about moving the brackets to a precarious perch hanging on for grim life off the edges of the uprights - no amount of gusseting will remove the angled leverage that this would give.

I have posted this before, but it does give the 22mm setback to give the castor, and now my car is driveable I can now say, hand on heart, that it does self centre nicely
Rescued attachment Wisbone Modification.JPG

The distance between the upper and lower ball joint centres is aprox 225mm. At this distance a 22mm offset will give you 5.5 degrees of castor as Mark says.

Mick

quote:

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Originally posted by Mark Allanson
I was unhappy about moving the brackets to a precarious perch hanging on for grim life off the edges of the uprights - no amount of gusseting will remove the angled leverage that this would give.

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Thanks guys, for your help.

Gary

If you are going to make your own wishbones then you can adjust the dimensions to fit the 'L' and 'FU' members.

Mick