Alright, once the jig is made, converting a swingaxle to IRS is easy. Our first
need was to convert a sand rail. I removed the spring plates and torsion
bars and cut away the bracing that would interfere with the installation of the
I then assembled the jig and the inner IRS pivot and installed it
on the torsion housing. The IRS pivot was welded in place and the jig removed. The jig gets
flipped over for the other side and the welding procedure is repeated. If
the IRS pivot is being welded onto a stock frame horn, the outside of the horn
needs to be cut away to allow for the pivot to slip inside a little bit
The rest is assembly. Install the torsion rods and either the IRS spring plates,
or the modified swingaxle spring plates. Bolt on the arm and
you are done.
If you want to remove the IRS stub that is common on the stock IRS spring plate,
the swingaxle plate can be used after simple modification. A drilling and cutting jig
can be made with a stock IRS spring plate, and a piece of cardboard, or thin
sheet metal. Trace
the shape and hole positions from the IRS spring plate and trace onto the
swingaxle spring plate. Be sure to flip the pattern over on one of them
since the holes are different from left to right.
The original holes are slotted to allow for alignment. If the car is to
be driven on the street, or there is a need for adjustment after installation is
complete, then the
holes can be elongated with a die grinder. A trip to the alignment
shop would be smart.