Independent Rear Suspension for Factory
The current generation Factory Five Cobras have an independent rear
suspension option. The earlier versions of these fine cars utilize a solid
axle ( sourced from Ford Mustangs ). The Factory-Five specific
rear suspension uses the same control arms, spindles, brakes, etc. as our
Universal IRS design, but differs from the Universal design in the location
of the coilovers and the overall design of the center section.
Similarly to the Universal IRS design, the IRS for the Factory Five
Cobras feature the following:
Gusset Removal - The gusset between the vertical 2x3 frame member (which runs behind the seat) and the upper 2x3 frame rail must be removed. A hacksaw will work but a power reciprocating saw makes the job easier. Replace this gusset with the round tube replacement gusset supplied in the kit. The new gusset is cut so that it does not sit as far toward the rear of the chassis as the original, allowing more room for the travel of the rocker arm. For the best effect of the new gusset, position it so that it intersects the chassis vertical and horizontal members as close to their outboard edges as possible and weld.
A 3" diameter notch must
be made in the original frame - for clearance. This hole is made in the
frame member directly below the reinforcment piece that was welded into
position in an earlier step.
Mark the position of the
3” notch on the side of the frame rail. The center is 1 5/8” forward
of the shock mount bracket (front surface), “A” and 2 ½” down from
the top surface of the original frame rail “B”.
Center punch at the crosshairs made by the "A" line and "B" line... Using a 3" hole saw will give the necessary clearance.
Using a 3” hole saw, drill
through the frame. Regular standard length hole saws are not deep enough
to do the job in one shot so be ready to drill from both sides of the frame
rail. Try to set the centering drill sufficiently protruding from the arbor
so that the centering hole is transferred to the inside wall of the frame
tube. This will allow the two 3” holes to connect in proper alignment making
a tidy notch in the bottom of the frame.
The resulting "cut-out" will look like this:
The 3" hole in the frame must be Deburr'd to assure a proper fit of the supplied 3" OD semicircular insert provided in the kit.
Slide the insert into the fresh cut to close the opening and restore integrity to the frame rail. Slightly squeeze (spring) the insert with a large pair of slip joint pliers ( if available ) as you slide it into the notch.
Weld all the seams surrounding the semicircular insert
Left Side Frame notch is complete... repeat these steps for the right side.