That aluminum bracket is 1/4" thick aluminum....
Here is a link to the weld in bungs for 3/4 x.058 tubing.. They come in both LH and RH threads...
QS Components Inc. Quality Racing Rod End & Components
Here is a link to the rod ends... LH & RH also... Be sure to order jam nuts with these...
QS Components Inc. Quality Racing Rod End & Components
Here is the link to the 3/4" x .058 chromoly... its at $3.64 per foot right now...
4130 Chrome Moly Round Tube - 4130 Chrome Moly
Here is a link to a 5/8" hub for a go kart wheel.. this will bolt onto the wheel and the axle will slide thru it...
5 8" Front Wheel Hub Plain Go Kart Racing | eBay
Parts list..
(4) 7'-0" pieces of 3/4" x .058 chromoly
(4) 3/8 x 3/8-24 Economy Male RH Rod End
(4) RH jam nuts
(4) 3/8-24 RH Weld-In Bung .058
(2) 3/8 x 3/8-24 Economy Male LH Rod End
(2) LH Jam nuts
(2) 3/8-24 LH Weld-In Bung .058
(1) 1'-0" piece of say 1" x 1/8" thick flat
(1) 1'-0" piece of 5/8" alum rod
I usually build um 6' long on the bottom bars... use the pieces you cut off the 7' pieces to fit perpendicular between the bottom bars..
Also, use the cut off pieces of 3/4" to hold the axle for the go kart wheel.. That axle will be out of the 5/8" alum rod and you can just drill a hole and pin the axle to hold it in.. Go kart wheel bearing should be 5/8" on both sides... You will also use the extra 3/4 chromoly to make spacers to center the go kart wheel in the bar...
Top bars on the wheelie bar will need a RH at one end and LH at the other.. The bottom bars I use RH on both sides where they hook to the pinch bolts...
The flat bar is for welding on top of the bottom bars in front of wheel to allow adjustment and connecting point for top bars..
I hope I'm making sense, I'm just kinda rambling on and on... :lol:
Disclaimer... May need more parts depending on how many times you plan on phuckin up.... :lol: