Frame question

[bobs66440]

For my fuel tank mounts, I just welded nuts into the frame...



[URL=http://s814.photobucket.com/user/bobs66440/media/T%20Bucket/IMG_20131231_091743185_zpsb579d720.jpg.html][/URL]

 

[fluidfloyd]

Jason, here is a picture of the K member in my frame that may help you.



This is the best shot that I have of the welded bungs. They go through the frame and are welded on both sides.



Jim

Jim,

I'm assuming you are referring to the suspension link bolts being through both sides of the frame rail. That is a great idea. By threading your weld in bung you have plenty of thread engagement for a single shear application. And if you just want to slide the bolt all the way thought then you can just add a washer and self locking nut. Lot's of ways to build these cars safely with minimal extra work. I do like your free articulating non binding suspension. I'm sure you've never been around any door slammer race cars,...or have you!

George

 

[fluidfloyd]

For my fuel tank mounts, I just welded nuts into the frame...

That too will work!

 

[TriodeLuvr]

Jack...Those just swell up in the frame hole and lock themselves in place. That still doesn't eliminate the drilled hole in the frame from being a stress riser.

George, couldn't this be placed into the hole and welded around the flange in the same way you described? How is this different?

Jack

 

[fluidfloyd]

George, couldn't this be placed into the hole and welded around the flange in the same way you described? How is this different?

Jack

Jack,

I don't really see a problem with that. You would need to chamfer your drilled hole deep enough to clear the radius under your flange. You need to have that flange flush to the frame surface when you weld it. It's probably easier then machining flanged bungs in the smaller bolt sizes. With bigger bolt sizes that carry higher loads like suspension etc I would probably machine them. The flange diameter to threaded bung diameter is a pretty big ratio. My concern would be a high load trying to flex that big diameter flange causing to to crack out. For the lite loaded applications I say go for it. Thanks for posting the drawing.

George

 

[TriodeLuvr]

Press this into your drilled hole in the frame and TIG fuse the larger flange diameter to the frame.

George, this is why I thought the weld nuts from McMaster would serve exactly the same purpose. It sounded like you were describing a part that would leave a flange above the surface. Maybe I don't understand the meaning of "TIG fuse." All my welding experience is with gas (and many years ago).

Jack

 

[fluidfloyd]

George, this is why I thought the weld nuts from McMaster would serve exactly the same purpose. It sounded like you were describing a part that would leave a flange above the surface. Maybe I don't understand the meaning of "TIG fuse." All my welding experience is with gas (and many years ago).

Jack

Jack,

Unless I had to have a flat frame surface I would just press in the flanged threaded bung till it seated. If the load was going to be a structural or stressed application I would either TIG weld it using a 1'16" or a .045" filler wire. If it was a lite load application I would just TIG the flange edge to the frame material using only the heat of the tungsten arc and the flange material. I could even use Silicon Bronze and really turn down the heat on the welding machine. Now if I needed a true flat surface I would chamfer the drilled bolt hole and the edge of the threaded bung. Press it in till it's flush and TIG well the "V" groove with a low amperage setting. Hopefully this will clear the muddy water for you. If not please let me know and I'll get you a drawing to look at.

George

 

[TriodeLuvr]

Now if I needed a true flat surface I would chamfer the drilled bolt hole and the edge of the threaded bung. Press it in till it's flush and TIG well the "V" groove with a low amperage setting.

I think I've got it now. You're referring to a chamfer that extends all the way out to the OD of the flange. By chamfering the flange as well, the two fit together flush. That says a lot for not using a large OD flange. So, for less critical work, maybe the McMaster parts could be turned down. For suspension mounts and the like, as you say, it would probably be better to machine your own.

Thanks for explaining everything, I'll need this type of frame work myself in the near future.

Jack

 

[fluidfloyd]

I think I've got it now. You're referring to a chamfer that extends all the way out to the OD of the flange. By chamfering the flange as well, the two fit together flush. That says a lot for not using a large OD flange. So, for less critical work, maybe the McMaster parts could be turned down. For suspension mounts and the like, as you say, it would probably be better to machine your own.

Thanks for explaining everything, I'll need this type of frame work myself in the near future.

Jack

Jack,

If you mean by turning down the insert flange OD to match the threaded shank then that would probably be OK for a true flush fit. If you mean to cut the radius from the underside of the flange so the flange will sit flat then I don't think I would like that as it would tend to be weak in that corner. I have used these type inserts in 10-32 and 1/2-28 thread on round tube. I still TIG welded the flanged edge with silicon bronze as they flanges wouldn't really seat up on the tube radius very well. I was using them to anchor small aluminum levers in Top Fuel cars for fuel shut offs and chute release cables. If I didn't weld them they would sometimes begin to spin when tightening or removing the fasteners. Sometimes they just didn't want to buck up tight in 4130 tubing. And I wanted to eliminate a possible point for a crack to start. Those cars are so violent and flex and move around so much that I just didn't want to take that chance.

George.

 

[RPM]

Why not just weld a simple tab on the frame and run a bolt through with a nut?

 

[Screaming Metal]

http://www.colemanracing.com/Weld-Nuts-P3980.aspx
http://www.on-b.com/doc/nuts.aspx

 

[Screaming Metal]

Jack,

If you mean by turning down the insert flange OD to match the threaded shank then that would probably be OK for a true flush fit. If you mean to cut the radius from the underside of the flange so the flange will sit flat then I don't think I would like that as it would tend to be weak in that corner. I have used these type inserts in 10-32 and 1/2-28 thread on round tube. I still TIG welded the flanged edge with silicon bronze as they flanges wouldn't really seat up on the tube radius very well. I was using them to anchor small aluminum levers in Top Fuel cars for fuel shut offs and chute release cables. If I didn't weld them they would sometimes begin to spin when tightening or removing the fasteners. Sometimes they just didn't want to buck up tight in 4130 tubing. And I wanted to eliminate a possible point for a crack to start. Those cars are so violent and flex and move around so much that I just didn't want to take that chance.

George.

Yep, on that moly tubing, I've seen the tire shake during a run or the bounce after the chutes open stress the frame enough to start cracks....

 

[TriodeLuvr]

http://www.colemanracing.com/Weld-Nuts-P3980.aspx
http://www.on-b.com/doc/nuts.aspx

Good links, thanks!

 

[fluidfloyd]

http://www.colemanracing.com/Weld-Nuts-P3980.aspx
http://www.on-b.com/doc/nuts.aspx

There you go! Looks like a lot of choices to be had. Doesn't look like much over 1/2-13 thread but that's probably as big as you would ever needed for lite weight non structural uses. I did notice on the lower link that they only seem to have course threads available. Mainly out of back ground and habit I use fine threads most of the time. Everything we build does get AN or NSA fasteners. Most cars don't really need them but race cars should. Thanks for the links Screaming.

George