Technical Suspension Gurus: Sway Bar question

OK. Looking for advice.
I posted this on my '49 Merc build thread but need a few more eyes on it.
I need to modify the stock sway bar to work with my new lower A-arms. First thought was to bend it until it might work, but I'd still have to make something to connect it to the Lower A-arm link pin. I'm not wanting to change the tabs on the powder coated arms.
New plan-

This should work fine if I cut the last bend off and:
A) Weld a tab to the bar for the link pins to bolt to. Or,
B) Use the bracket I made (shown), slip it over the cut bar, and drill through/bolt to the bar with two 1/4" bolts. Cutting through spring steel might **** a little.
There is a little "play" between the bar's OD & the tubing's ID. Probably could put some PTFE tubing or something in there to take up the space & make quiet & smooth. Or,
C) Cut the bar about another 2" shorter (about 4" total/side), drill/tap the end, and use that to bolt a Heim end to it, which would be the top end of the link pins.
These are listed in order of ease, and parts available. Welding to the bar is frowned upon, but it would be right at the end, and I doubt it would cause a problem. I'd prefer to use stock style GM link pins with rubber bushings (I have a new pair), so A & B are my first choices. C would be easy to do (except for drilling the ends), but I'd have to find some 3/8" female rod ends, and since they all seem to be 3/8-24, they won't screw on the 3/8-16 link pins. So, I'd have to get new fine threaded bolts for those. A trip to get hardware is about a 30-mile round trip for me.
B is the way I'm leaning. After some web searching, I see drilling through the bar is done quite often. And I'm ***uming that shortening the bar will make it stiffer, which I don't see as a bad thing (it's only 3/4: dia). I'm not expecting to do any autocrossing, or other high-speed cornering, mostly just cruising low, but not always slow. Thoughts?

 

My front bar has tabs welded on the ends for link pins and works fine.

 

As a former suspension validation engineer, do not ever weld on an anti-sway bar (or any other spring). The weld creates a stress riser that will result in a fatigue crack and failure much sooner than you would like. You would be better off to heat the ends up to a bright orange heat and hammer them flat and then drill a hole for your link mount.

 

OK. Hadn't thought of that. But, doesn't heating it up take the temper out of the spring steel? I don't want to have to send it off somewhere to get re-tempered.

 

A clamp on link is pretty common on older race cars.

 

There are times when I really wish the argument in me didn't come out...so I'm going to suggest you think about this, most bars have a flattened end with a hole. The bolts is usually 5/16 or 3/8" and it's rubber mounted. You're overthinking it. If you can take up the slack slop or looseness, I like (B). Simple and effective. (A) won't end the world and again, welding isn't as much the problem as much as the way it's cooled is. (C) to much like work if you ask me, but would sure look expensive and fancy.

 

@Oneball I thought of that, and Googled clamp on sway bar ends/brackets and didn't find much. I'll dig deeper.

 

Something like this could work.

 

Yes it will, but you aren't using the bar as a spring at the ends where the links attach. The "springy" part is in the center between the mounts were the bar twists back and forth.

Clamps are a better solution. Look into the roundy-round dirt track guys. Lots of anti-sway bar options, links, clamps, mounts, etc.

 

What's the diameter of the sway bar?

 

@Algoma56 3/4"

 

I went for it and cut the last bend off the bar. Slid my homemade bracket on to show what I'm thinking.

Nothing is tightened or lined up, and I'm thinking I should gusset the tab onto the tube (because-overkill).
This looks like it will work fine to me. The only question is how to attach the tube/tab onto the bar. I was thinking drill/bolt through would be best. Welding might cause temper issues, but I don't think it's a super high stress area. As stated by @FrozenMerc, the spring action will really come from the straight part of the bar, between the first bends. Anybody? Bueller?

 

That Looks nice to me and I wouldn't hesitate welding The tab to the bar, but I'm a knucklehead.

 

I'm not personally a fan of either 3/8 heim ends or clamp-on end links. I've used both, and they proved to be regular replacement/maintenance items in semi-daily street use. Granted, some roads I travel aren't the best, so YMMV. Good race car bits though...

Your last pic looks fine, weld it on, although I would gusset it a bit.

 

If you don’t want to weld, how about grinding a couple of flat spots or grooves in the bar and drill a tap the tube for a 1/4 inch bolt . Think set screw , and lock tight .

 

@Crazy Steve I raced asphalt circle track in the mid '80s-early '90s and never saw a clamp on end before today. Of course, I was running street/super stock, not late model or dirt. I Googled and found them. Probably would have worked, but I don't want to have to check/retighten/etc. The Heim ends would also work, but the more rubber in there, the softer the ride (it's a street car).
I have since gusseted w/ 3/4" triangles on each end of the tubes, and drilled holes through to bolt it on. But it would be easier to rosette weld it to the bar using those holes...

 

I am glad you added gussets between the tube and flange. That would have torn off in fairly short order as designed. You would probably be fine rosette welding it through the holes to the bar as the tube will help reinforce the bar at the load application point. Not ideal, but it will probably last as long as you need it to.

 

Most bar material is likely manufactured from 4130 material. Is it heat treatable, yes. But what exactly do they mean by heat treated is the question? Seems many are saying such and thinking it must be made magical as a result of being "heat treated", this results because the term is used so broadly to describe many things and many conditions.
Heat treating, while nothing more than heating and cooling at its simplest, will change mechanical properties of the bar, by altering grain structure. As manufactured, the bar itself has due to elemental composition of materials a set grain structure and defined mechanical properties as a result. A degree of hardness, and resulting elasticity due to hardness to allow it to perform by offering more or less resistance and a return to its original shape when stressed. Heating to bend and shape it will alter this grain structure and of course, the properties of hardness and it's resulting elastic limits.
Heat treated...How about the bar after manufacturing into a shape, is then "normalized" to return it back to its original condition restoring mechanical properties and grain structure?
4130 is a weldable material. Due to an elevated carbon content, a degree of care must be utilized when welding, same for cooling to avoid excessive hardness and the risk of cracking. usually as simple as preheating and post heat. But as far as it goes, where's it going to go?

 

@NoelC states:
"4130 is a weldable material. Due to an elevated carbon content, a degree of care must be utilized when welding, same for cooling to avoid excessive hardness and the risk of cracking."

Yes, this seems to be common knowledge, but to what extent? Some say they've welded on bars, and it's worked for 10 years/ 40K miles. Others say if you weld it, it will break. Of course, I haven't heard any of them say "I welded a tab onto it, and it broke the bar in 10 miles." Or "it broke in the first hard corner."

I have seen guys narrow GM subframes for use under an older car, and they cut/welded/sleeved the sway bar. And this is right in the center, where I think the most twisting occurs. The problem seems to be the difference between what happens in the real world, vs what metallurgists and engineers tell us "will" happen.

I have decided to drill through & bolt the tube/tab to the sway bar with (2 each tab) 1/4" gr8 bolts/lock nuts. Now, drilling steel with an "elevated carbon content", will take some good drill bits and some finesse. I'm low on both of those.

 

https://www.astmsteel.com/steel-knowledge/4130-alloy-steel/#:~:text=Hardness: 4130 steel has a,weldable in all commercial methods.

Take a hammer and a center punch and see if you can dimple it. That will give you an idea on how hard it is.
Regarding the welding of it, or welding on it...lots of kids play doctor but I wouldn't trust many to perform surgery. Same with welding. Some see it as hot metal gluing and some see it as a surgical art form.
Regarding metallurgists and engineers...some p*** with honors and some just p***. Doesn't mean they can weld or operate but they do live a****st us in the real world just the same and most carry insurance just in case.
Sharp bit and some cutting fluid it shouldn't be a problem drilling. Carbon content doesn't effect that, but a heat treatment might. So, if you can't dimple it with a center punch, all bets are off. And yes, better safe than sorry, less harmful drilling than welding and even without, I don't see it going anywhere as it is, but it can't hurt either.

 

Thanks @NoelC. Your knowledge on the subject is exactly what I was looking for. And I appreciate your anecdotal way of phrasing things as well. I'm not an engineer or metallurgist, but I'm also not a RR type builder who fires up the ol' Lincoln 225 and burns rebar and chain together to make steering components. I try to build my stuff to be functional, and safe. Not just for me & my p***engers, but for the other people on the road as well. I couldn't live with myself if something I "engineered" failed and someone was injured or killed because of it. I also try to not spend all of my retirement money on getting "professionals" to build me things (like a custom sway bar, or completely new ch***is), when I can find a different factory or aftermarket part that fits, or modify something (safely) that will work well. Once again, it's appreciated. As I stated, I'll be drilling and bolting, and feeling safe about the way it's been accomplished. Thanks for everybody's input.

 

@1pickup I share you concern about welding that sleeve on. I think the bar will eventually crack at the weld point. But trying to drill thru that bar, ugggghhh, I imagine that is not going to be a walk in the park type of job. Got a bit sharpener? I used to be pretty good at sharpening bits but seem to have lost the knack. I thing what I would do is slice that sleeve down one side and weld some tabs to it on either side of the slice that would allow it to be clamped tight around the bar with a couple of grade 8 bolts.

 

@Blues4U Ha! Great minds think alike. I had that same thought yesterday.

 

47 years ago I cut the ends down on a '70 Coronet police car front sway bar and shortened it and welded the flat ends back on and installed it in my '62 Lancer with a 340 in it. Still on there and has never cracked or broke.

Dave

 

1 hole = 1 drill bit.
So far: 2 holes drilled completely, 1 about 3/4 of the way, and 1 about 1/4 of the way.
2 new Cobalt bits that don't want to cut anymore, and 1 HSS that snapped the tip off when it caught going through. Another trip tomorrow.

 

Elephant in the room. If you use this method to attach the bar you do not want to fix the bar to the bracket. That will cause bind. Needs to be able to slide as suspension articulates. Look at cars with a similar attachment. They'll have slight witness marks where the bar moves

 

I would scribe a line on the bar next to the bushing. Then move the suspension through its arch and see how much the bar moves in and out of the bushing. That will tell you if it should be welded or left to move in and out.

 

Sorry to see you are 3 drill bits into bolt holes that will probably cause problems. the angles of the arch the control arms make, and the arch the sway bar will make are completely different, solid mounting at that point will most likely fail.
I too would have modified the tube by splitting it and making it two pieces that could be bolted together. I would probably add rubber between the clamping method, the two arches are still going to be in conflict. A bit of give there at the bar, and the rubber in the link between the tube and the control arm may provide enough give to keep things from failing.

 

I'd like to point out a couple of moot points. With opinion, Cobalt bits are overrated, oversold and quite frankly, rarely required... but that said, it worked. We are not there, you are, and getting the job done is the end result. For that matter, we don't know if you had an air drill, a Sears 1/4" chuck special, or a Black and Decker 1/2' variable? If you powered thru with a single 1/4" bit or if you two stepped it with a pilot hole first? Did you use cutting fluid or did you dry dawg and push thru it?
Second to that, the bar is firmly attached in front, so it has no real movement front to back does it? So, up and down with suspension movement up or down. And it's wrapped by a pipe sleeve welded to a plate, the plate acting as the attachment to a typical rubber mounting. Is it really necessary to drill or weld to the bracket you have made? I don't think so, but that's just me asking where it's going to go? What will it take to get it to go there, you could ask that as well? It can't turn because it's held by the bar. Not like it's going to slip out if it's all the way on at it appears you have it cut to do so?
What surprises me, is after getting the suggestion to split it into a clamping bracket your choice was to drill holes. That right there for me would have been a moment to change things.

 

Well, it's too late. Holes drilled (before the suggestion, and after I already thought of it), parts cleaned & painted.

As for causing a bind - I doubt it. Here's why: I made sure the links are as close to straight up and down from the side view as I could get them. The lower A-arm also goes pretty much straight up & down, so they are on the same plane, or as close as I could get it. They are also attached to the GM end links, that have 4 rubber bushings/side. That should have plenty of deflection.

Now, making them "float" on the bar seems like a bad idea, as that means the bar would have to move farther, before it actually starts to be useful by twisting & acting like a spring. Thus, inducing more body roll. ie: the bar would move, the tube would twist on the bar (so the bar would move farther), then it would find a spot to stop twisting (like squishing the rubber bushing on the link), then start acting like a spring.

It's done. If I had to do it again, I'd weld tabs on the shortened bar. If it fails, I'll post it, and you can say "I told you so." If in 20 years it's still on there in one piece, and I'm still here in one piece, I'll post that too.