Solid Threaded Inserts

[kabuku6]

With my wide Mustang axle I've decided to take the path of utilizing longer support arms for my 4-link. This type of mounting isn't covered in the book, so my thoughts were to put a threaded sleeve in one of the vertical supports. (not "H", but an additional vertical support that I installed at the end of "K1, and K2".) Also adding in an "L" Br@cket on the front of the tube to sandwich a rod end between that and the threaded insert in the frame.

Br@cket.png

As far as using a threaded insert, all I can find in 1/2-20 are coupling nuts, and they aren't very locost, or do they look like anything special. A thought that comes to mind is using some 3/4in tube with .156 wall. (I found some at http://www.stockcarsteel.com) which gets me down to .438" and the hole size for 1/2-20 threads is 29/64, or close enough to .45" an easy step up.

What is the consensus, on the strength of that setup? Is threaded tube going to be strong enough? My thought is that I could pean one end of the insert to create a type of stover nut, or just red-locktite the bolt into place.

Am I over thinking this? I feel like just welding a nut into the frame wouldn't have any strength in the unlikely event of twisting loads.

[davew]

I would use heavy wall tube that you can cut threads into, inserted into the frame, which will prevent the frame tube from deforming from the load and tightening stresses. Put a tapper on both ends of the threaded tube insert, which will increase the area for weld penetration. When drilling the hole in the frame tube, do not drill all the way thru the very last bit of the tube wall. You can then use a bolt and washer to hold the threaded tube in place while welding the opposite end. If the insert does not have to flush on both sides of the frame tube, I would extend the insert be on the frame tube, so you could get more weld around the OD. Finishing welding, and with the tapper tube end(s), it will allow you to grind the weld flush with the surface, and still have good weld contact around the insert. Once completed, go back and run your tap back thru the insert.

[Lonnie-S]

I think it's a very clever idea. Dave's proposed method (above) sounds like it would be very strong.

If it were me, I'd make the "L" shaped bracket "taller." That is, larger in the vertical dimension as we view your screenshot graphic. My reasoning is that I'd want to move its welds further away from the welding of the insert, and make sure the control arm bushing ends are fully covered by the bracket itself. That's just me.

Cheers,

[kabuku6]

Dave: It took me a couple reads to figure out what you meant by not drilling all the way through, Basically drill and half inch hole on one side so I can hold the insert with the bolt and washer?
Thanks for the input those all the points sound like good practice.

Lonnie: I just made a quick mock up to visualize, but that's good advice on the Br@cket size. Might go with something closer to 2" tall to spread out the weld.

Thanks fellas!

[Sean in CT]

I would find tubing with an ID smaller than the size you are drilling. The tubing get work hardened from the drawing process and is much more difficult to tap compared with a smaller ID that was drilled to size. At least that was my experience.

There are online machine shops, such as E-machine shop, that might be able to make the bushings you need for a very reasonable price. I have used them a bunch of times with 100% satisfaction, They have free CAD software too
Leaving a small flange on the non threaded side, will make it a lot easier to weld in place

[Lonnie-S]

@Sean in CT

Sean, is the shop you're talking about this one here?

If so, maybe you could do a little entry in the "Tools and Fabrication" section of the forums here. I'm interested in learning about them and I bet others would too.

Cheers,

[Sean in CT]

Lonnie. I have never used XOmetry, but their website pops up when searching for E-Machine shop

I use

https://www.emachineshop.com

sendcutsend is the other one I use

[kabuku6]

Don't know if I'm using it right, but I already had emachineshop on my laptop. A 3/4" tube with 1/2-20 threads was gonna cost me something like 30$ a part?

Otherwise, it's pretty easy software to get the hang of.

[anduril3019]

You can find a lot of stuff like this, brackets, bosses, gussets, etc., on the circle track, hot-rod, and off road supplier websites. A lot of it tends to be a little overkill for a light weight car, but I've found some nice pieces and saved some fabrication time by digging around a bit.

https://www.hrpracing.com/0-750-inch-od ... -20-thread

https://www.pacificcustoms.com/fabricat ... -road.html

https://aa-mfg.com/

[kabuku6]

Thanks for those links. Definitely some useful stuff in there. Looks like A&A has something I might be able to make work, at a price that makes sense too.