GT40 Radius Arm vs SLA Rear

[Henk]

First, sorry if this isn't in the right section for being not-necessarily-GT40-tech.

I'm scratch designing and building a mid engine 'pickup', and have always loved the rear end chassis and suspension setups on the GT's.

My original plan was double wishbone front and rear, but putting the pushrod suspension on the chassis and mounting the wishbones etc properly on node points of the chassis is a bit of a struggle.

The GT40 style (used on plenty of others i know, but i'm sure this is the most common application these days) however would work really really well on the chassis.

However it's not something you see used 'these days', is there any reason for this, apart from being somewhat prohibitive due to size? What are the downfalls?

double wishbone is almost certainly the easiest to work with and most adjustable, camber compensation, roll centre location, squat/dive and so forth!
However I assume that in a 2D view the radius arm setup can be viewed as double wishbone?

By the way is there a more correct name for the suspension design?

 

[Mike Pass]

The long forward links on the GT40 type setup move in an arc which pulls the upright forward or backwards and this alters the F/R angle of the lower (and upper) wishbone which changes the toe in. If you think of this setup as a very wide wishbone with the pivot axis (the line through the ball joints) at a fairly large angle to the car centre line. The toe in on the rear on the GT40 type setup can be set by moving the inner end of the reversed lower wishbone backwards and forwards (as on the GTD) or by lengthening or shortening the long links which run forwards to the chassis.
The normal double wishbone has the pivot axes parallel to the car centre line so there is no change in toe in as the suspension moves up and down. The GT40 suspension is easy to create and the acceleration and braking forces are taken directly fore and aft to the chassis with low bending forces on the back of the chassis. The wishbone setup causes a bending effect on the back of the chassis as the acceleration and braking forces are applied at the outer end of the wishbones. However the geometry is better with double wishbone and with very stiff modern chassis it is the way to go.
I usually call the GT40 type of setup a trailing link system but I don't know if this is technically correct.
Cheers
Mike