Boxed control arms or anything else.

[li7in6]

More of a curiosity than something I plan on attempting to tackle in the foreseeable future. How do fabricators make fully boxed control arms (not boxing OEM pieces). I understand the concept behind them, but how does one go about welding and joining all the connections inside of a boxed structure you plan on closing without painting yourself into a corner, so to speak. This has farther reaching application than just suspension components, and I realize might be too broad of a question for a simple answer. And is more to do with experience and order of assembly. But I'd like to get a general idea of whats involved and how its planned for.

For instance, internal ribbing/support in a control arm. I can see how to fab the basic structure and internal supports, but how does one close the box and tie the supports into the "cap" peice without magically teleporting your welder through a steel plate.

One of the ways I can see it being done is using smaller plates and welding the outer shell as you go, possibly using a solid base plat for the lower and piecing together the top. Obviously you're plate work will need to be rather intricate (as with the Herbst TT lowers below)

Another way i can think is to have you're top/finishing/whatever plate have reliefs cut so you're internal bracing can come through and allow you to fuse it to the plate from the outside, but it seems like you'd have to be pretty precise with your cuts. though I guess fabbing suspension arms is pretty precise work in the first place.

From looking at the pics I've seen and looking at the weld burns/penetrations, it might be a combination of these and more.

How do they do it with apparently solid top and bottom plates? Are the arms just hollow?

Any help is appreciated.

pictures for 'how dey do dat' reference:

Assorted pics from Terrible Herbst, Mazulla, Atomic, Boneyard, Camburg, etc.

 

[DHPmike]

I make arms but out of tube. I have made plate and box arms. Its done by building a bowl of all the outer pieces and the braces, similar to making a steel fuel cell and adding anti slosh baffles. you cut lines in the top or drill holes where the braces are and then weld them up in the end.

It takes alot of jigging to get a part that nice every time.

 

[li7in6]

I make arms but out of tube. I have made plate and box arms. Its done by building a bowl of all the outer pieces and the braces, similar to making a steel fuel cell and adding anti slosh baffles. you cut lines in the top or drill holes where the braces are and then weld them up in the end.

It takes alot of jigging to get a part that nice every time.

Yea, thats pretty much what I was visualizing. I don't think I'm near the level in welding/jigging to try one, but I might play around with it on scraps.

 

[DHPmike]

its a PITA to make a jig for any complicated part like a control arm. Thats what I do is make arms, BUT its a major PITA to make the opposite side matching jig. Then its also a PITA to make both arms the same.

Most of my drop arms are made on the same jig just flipped over because they are pretty much flat. Most of the time theres about 4 times as much time spent making the jig than the actual part.


I use 8mm thick AR500 armor plate for my jig bases then I have to get a hole cut on the CNC plasma where I can weld in a sleeve for the mount that holds it on my stand. Then theres other holes for bushing sleeves etc. I try to make the upper jig on one side and the lower jig on the other.

I also have a 12"X36" lathe to make the bushing sleeves and I use DOM tube in various diameters and thicknesses for those. I use ONLY Energy Suspension graphite impregnated polyurethane bushings. I make the inner and outer sleeves myself.

My braces, tabs and most of my bag plates are 3/16" or 1/4" HR plate. some of them where the bag will be in a certain place and not moved I make from armor plate.
I also try to use factory balljoints when possible. sometimes they have bolts that are in the way so I use some other factory one or a screw in one.

its alot of planning.

 

[li7in6]

Thanks for the insight. Where did you learn this kind of fabrication?

 

[DHPmike]

Ive been studying suspension since I was a kid. First it was dirt cars and trying to figure out how to make a regular dirt car suspension turn better. This was back in the late 70s when all dirt cars except sprint cars ran 55-57 frames. Then they went to Camaro from 70 to 82. I realized at an endurance race that the chrysler cars from the 70s and 80s had torsion bars and could be cranked up on the right and down on the left. The rule was to use stock suspension. spring clamps and rubber spacers were ok.

Then in the mid 80s I lowered a 66 Ford truck by installing a Torino frame clip in the front and stepping the frame in the back. This was learned working at my dads shop putting Camaro clips under old chevy trucks. we could do one in a few hours. they would bring the truck with no motor, no front end sheet metal and the camaro clip and the motor in the back.

well my 66 had a front bumper that was 2&1/4" off the ground all the time, no adjustable suspension. I then helped several minitruckers lower their import minis and some domestics.

I started building suspension parts when I built a Mazda Limo for a friend. I started building several minis at a shop I opened in 1994. I started building control arms with corrected balljoint angles in 1998 and started building control arms commerically in 2003.

Ive built hundreds of sets of arms since then and had success and some failures. Ive learned that testing it the best thing you can do.


I dont have any experience with lifted suspension tho..

 

[ckblum]

DHPmike you should look into fabricating some long travel control arms. I bet with your experience you could crack out a wicked set and theres a pretty big market with all the Toyota's and newer Ranger's.

 

[DHPmike]

I may get into that at some point. Im covered up in drop parts right now. Im going to expand at some point in that direction but Id like to get some 4x4 guy in my shop before that.