Welding Tips and Tricks

i have plans to build a swing arm for my quad and instead of spending 600 dollars on a aftermarket one that i dont like i thought id make it on my own. if i use aluminum it will bend like a noodle this part thakes the most strain of anything besides the shocks and so i am going to use steel im thinking ill get some thick walled inch and a half 4130 round tube and build it out of that but before i do this i need a better tubing notcher, but anyway i currently weld mig but would like to learn tig can a tig hold up to some pretty thick stuff and if so what tig should i get, this will not be the first thing i make if i do tig, i have plans for it and i have made several models out of pvc piping so now im down to making it and like i said i am not looking for this to be done anytime soon the dunes where i ride are closed till october. the plans are in the shop right now ill put them up later, so what steel should i get it needs to be steel and inch and a half and should i tig weld it and i am needing tig anyway so what one should i get needs to do aluminum and steel this is the old one that i am currently powder coating

these are the plans to build it and the half scale model

one basic problem is the amount of unsprung weight.
that makes a lot more work for the shocks and especially on light weight vehicles it causes handling issues.

i would look at where the factory one fails, look at improving that design and keeping the weight to an absolute minimum by using good design.

Aluminum swing arms won't "bend like a noodle". Most motorcycles and quads use ally arms quite successfully. The unit in your picture is one too.

The brackets look "dodgy" but that can also be attributed to "use" and "mistreatment" as much to design. Thick walled 4130 will be 3-4x heavier than stock. What's the point? As pointed out, unsprung weight is a problem for steering geometry and handling.

TIG or MIG doesn't matter. Both can be equally strong when applied correctly. Most stock swing arms and motorcycle frames are MIG welded because its much, much faster, can be automated easily, and can be dialed-in to near perfection.

Only issue I see is the calculated / engineered issue. Liability is a bitch! AtV are by nature an abused devise. But there often off road use only, another grey area. Weight of device/ plus weight of rider. Terrain ridden, flat track, ramps, ? Lots of variables. Any advice given would need more specifics. Unless backed up by the details it would be at best a guess.