Hello
The rotting rear axle support has been a constant problem on my Fourtrak as it has with many. After various patch up jobs and welding fixes I decided to start from scratch and have a go at making a whole new one. Not a new idea I know but I added my own addition to try and make this part easier to get in and out for repair.

(1) took exhaust off to allow better access
(2) released handbrake cables at front of Fourtrak where the bracket holds both cables
(3)Loosened the 2 bolt on the brackets rising up at an angle from the axle which hold the drop link going to the axle support.
(4) Loosened the two bolt on the brackets on the S bend axle support pipe.
(5) Cut the brackets of the old S bend support pipe and kept for future use.
(6)Measured the lengths, bends and dimensions of the new Axle support to fabricate from box section staYing as close as possible to the original S bend pipe.
(7) Cleaned the remains of the S pipe from the inside of both sides of the chassis at the heavy collar support.
(8) Marked the dimensions and angle bends of the new pipe on a piece of ply so as to use it as a guide when welding up the new one.
(9) Using the guide cut and welded the new box section support.
(10) Purchase the heaviest Bolt/Nut that would allow nut to slide down into open end of box section with angles cut off - pics will explain.
(11) Fit the new box section so as to make sure it fitting inside chassis, allowing the old brackets cut from the old support to be welded on the straight part of the box section - pics will explain
(12) when sure box section right fit take out and weld the nuts down in about 10-15 mil inside open end of box section. Only set back in here so as to allow a good weld to hold.
(13) then refit exhaust brackets and brake line bracket and the oval shape bracket that allows the two handbrake cables to be held below the new support. Just spot weld these before a preliminary fitting of the exhaust to make sure in right places. The box section is a different shape to the old curved pipe support so brackets may be in slightly different places.
(14) When content the exhaust brackets and other brackets mentioned are right take out, weld properly and paint new box section support.
(15) Fit exhaust properly
(16) Reattach handbrake cables at front of the Fourtrak below where handbrake comes through the body.
(17) Now when fitting permanently use the two large bolts. These will be passed through the outside of the chassis on both sides so as to go through and screw into the bolt welded in the open ends of the new box section support. You could fill the new box section with waxoil or grease at this stage although due to the bolt through the chassis no water will get into the inside of the box section.
leave loose so as to a allow it easier to fit the two bolts in the brackets at the axle side and the two at the new box section support side.
(18) When the fitted and pulled tight the large bolts can be tightened on the outside. They will need to be pulled very tight so as to pull the box section against the chassis on both sides and tighten on the now hidden bolt to make the support as strong and solid as possible.
(19).**********IMPORTANT The bracket holding the brake line will have to be welded once the support is in situ so make sure battery leads are loose and off terminals for this if you are using an arc welder which I was***** IMPORTANT
Pictures will hopefully explain things I have not explained that well above.
Hope this helps as many as possible with solving this long running issue.