Swingaxle to IRS Conversions
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Sandrail IRS Conversion
Stock Bug IRS Conversion



We have come to the point where converting swing axle rear torsion housing to IRS has become necessary.  We have several good pans that are too good to throw away yet we do not want to run swing axle.  We also have our custom pan with custom torsion housing projects that need to have the IRS pivots installed.

We have done two types of IRS conversions.  The first was a tube frame sandrail with a custom torsion housing.  The second was a stock VW pan for a Baja Bug.  While some of the steps and the results are the same there are some very important differences between the two.  Mainly the stock conversion is a real pain, due to the amount of metal removal from the frame horns.

On with it already!


The first step is to make a jig that will hold the inside IRS pivot in place.  This was a simple part to make.  

The parts you need for this are:

bulletAn existing IRS torsion housing with IRS pivot in place
bulletAn IRS pivot bolt
bulletThree of the IRS pivot bushing centers
bulletA 5"x7" plate of at least 1/4" thickness or spare stock spring plate cover
bulletSome 1" tubing, 1"x1" angle iron, or thick flat bar,  (something that will not bend or flex easily)

I cut and drilled a plate that would bolt on to the spring plate cover and bolted it in place.  I then welded two of the spacers together to form a single tube.  I cut the third one in half to use as a spacer.  I then installed the tube and spacers on the IRS pivot with the welded tube to the inside and the spacer next to it with the bolt tightened up snug.

The next step was to make the connection between the plate and the tube.  At this point, whatever you have laying around that is reasonably rigid will work.  I used 2" by 1/4" flat bar.  Cut and fit the flat bar to form a U shaped connection between the plate and the tube.  Be careful not to weld to the spacer or you will not be able to get it out.


irsjig01.jpg (44391 bytes)  irsjig02.jpg (52353 bytes)  irsjig03.jpg (46794 bytes)  irsjig04.jpg (47825 bytes)

Sand rail IRS Conversion with this Jig


The first thing we needed to do when we started the stock conversion is to make a new jig.  The jig we made for the sand rail worked great, but did not clear the stock upper shock mount.  It would work one way, but not the other.  So we dragged out the IRS torsion housing again and proceeded to modify the jig.  We needed to extend the support arm so it cleared the upper shock arm on both sides.   After much deliberation on what we should use for the new arm we settled on what I tripped over.  A couple cuts, some grinding and a bit of welding and the new jig was ready to go.

irsjigmake4.jpg (26477 bytes)  irsjigmake5.jpg (19865 bytes)  irsjigmake6.jpg (28260 bytes)  irsjigmake1.jpg (25791 bytes)  irsjigmake2.jpg (22769 bytes)

irsjigmake3.jpg (22620 bytes)  irsjig1.jpg (18476 bytes)  irsjig2.jpg (17333 bytes)

Stock bug IRS conversion with the new Jig


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Last updated: February 27, 2014.

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