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Full Version: Home Made Heim Joint Struts
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Hello All,

What follows is a post I did on another forum and I thought it might be useful to some here. It was done on a 69 Fastback but it applies to multiple years.

I've been researching and designing a heim jointed strut for a little bit and have just finished making one so I figured I'd share my knowledge.
Here is the design I got off of Dazecars It's a really cool site and it got my brain thinking on several suspension projects.
I modeled it up and made a drawing of the parts.


There were a couple of things that I didn't like about the design.
1. I didn't want to try to make the Spacer (Item 9) have an internal hex shape.
2. I wanted to make sure that the washer that fits onto the Clevis (Item 1) laid flat. The clevis would have draft (an angle where the mold splits) and would make the Washer (Item 7) "rock".
3. This design required that you have a fairly precise measurement of the thickness of the metal where the strut mounts to the frame. I wanted to make it so you wouldn't have to worry about this. This would also remove the need for washers to make up the space behind the Front Washer (Item 8) so it would deflect when mounted.

So, this is what I came up with. I used Dazecars recipe for the purchased parts. It was kind of funny when I ordered the Threaded Clevis. You have to call them to order them. I wasn't sure if they only dealt with big orders so I asked the guy if they sold to residential places and he said, If you've got money, I'll sell you anything. When I told him the part number and that I needed just two of them, he said, "Do you have an old mustang?". So apparently, they get this request a lot.

Here are drawings of all the parts I was going to need to make or modify. If anyone wants a full size copy of them, let me know and I will get you pdf files of them.
Here is the Modified Clevis (Item 1). It's important to keep a radius in the corner to avoid a stress concentration. These strut rods deal mostly with a tension load on breaking and acceleration. They see some compression/tension loads on bumps and pot holes.
Here is the Washer/Spacer (Item 6). Since I was making these parts, I figured I could make the washer and spacer one piece thus the brilliant name Spacer/Washer. This also allowed me to make the diameter match closer to the hole in the frame where it mounts. Note the chamfer to allow for clearance of the radius on the Modified Clevis.
Here is the Front Washer (Item 5). Making this thicker than a standard washer allowed me to put a counter bore that it deeper than the spacer part of the Spacer/Washer. This eliminates the need for having to match the thickness of the mounting metal. I also don't need the backing washers since the piece will no flex inward when mounted.
Bronze Insert (Item 3). Straight from the hardware store, just needs to be trimmed. Accurately!
Here is the Modified Strut (Item 8). Again, the nice thing about turning this on the lathe was being able to put a chamfer on it where it tapers down to reduce stress concentration.
Two bolt modification drawings (Items 11&13).

This ends part 1.
Ok, so that is the fake world of CAD, here are pictures and comments on the making of this assembly.
The first thing I did was start with the Modified Clevis.
I had to switch over to my four jaw chuck to grab the part. I also had to use a of couple cutting tool to pinch the part in this photo's "X" axis.
Here is another shot showing the draft from the casting process. The goal here is to remove the hex feature and to remove the draft and make a nice face for the Spacer/Washer otherwise it will rock.
Using the tailstock to help support and center the part. It took a little time to set this part up but it was worth it since I got what I was looking for.
Part after cutting. Nice clean flat face!
Before and after picture.
Next was grinding the opening. this is only required if you are using the Heim Seals (Item 4) since they add another .100" to the heim thickness. I wish I had my mill up and running for this since it would have been nice to use it. Instead, I had to use the old trusty grinder. It worked out well just take your time. Once you get the thickness correct remove the flashing from the area where the thread come through. This will provide clearance for the heim joint.
Here was my stock material for making the Spacer/Washer and Front Washer. It is 2.500" 1018 steel. It machines really well but the parts will need to be painted. 6" cost me only a whopping $15!
I first thought I would cut the blanks off using the lathe. This turned out to be a pain in the ass. Lots of chatter. I had to finish this one off with a hacksaw. 
This experience prompted me to get one of these. I needed one anyway and it saves you a tone of time and headache.
Here is the blank I started with for the Spacer/Washer. Riveting isn't it?
After cutting the Spacer feature into it.
Flipped over and facing the back side.
Finished thickness of Washer Feature.
Drilling out the center so I can start the boring process.
Boring out the center to fit over the clevis.
A little polishing with some fine grit sand paper and it's done.
Fits nicely on the Clevis. Although it's not critical to the function of the assy., I tried to make the fit tight.
Facing the Front Washer.
Using the compound cross slide to get the chamfered front face.
Finished chamfered face.

Drilling out the clearance hole for the mounting bolt. Drilling with the tailstock is sooo nice.
Finished part. I cleaned up the counter bore to match the Spacer feature of the Spacer/Washer that uses this pocket.
Trimming of the Bronze Insert. This needs to be done accurately since it need to be about .030" shorter than the heim plus the seals thickness.
Pressing the Bronze insert in. You can use a vise to do this if you don't have a press.
The insert is longer than the width of the heim joint so that it will captivate the Heim Seals. Once you bottom out the insert, you need to press it in a little more. I used a socket to allow me to do this.
It's a good idea to check that the insert sticks out the same amount on both sides of the Heim Joint.
Here is a picture of the Heim Joint with the Bronze Insert pressed in and one of the seals set in place. You cane see that the insert is a little shallower than the seal. This is what you want since you want the clevis to pinch the seals and ball part of the Heim Joint and not the insert.
Here is the assy so far. As you can see, the bolt needs to be trimmed. Jim, Why did you pick such a long bolt?
This picture shows the non-threaded part of the the 1/2-13 x 3.00" bolt. It works out well since you don't want the Bronze Insert riding on threads since it will cut into the bronze. The non-threaded part will spread the loads better.
You can see that the mounting 7/16-20 x 2.000" bolt need to be cut down too. For similar reasons here.
So here is the assy up to this point. Make sure that the Hiem Joint can move freely and doesn't bind anywhere.
Here is my stock strut in the lathe. I was very cautious about cutting into it. Take your time here.
I had to use a three point support and slow speed to turn this part. It worked out surprisingly well and was a lot less violent than I thought it would be.
Here it it spinning
Once I had a clean trued surface, I cut off only the tip and mounted it back into the car along with my heim assy to see where it would be best to cut it. This is the finished diameter with a chamfer.
Threading the strut with a 5/8-18 Die.
Finished threading. I made it a little long and then cut it back again just in case there was any issue threading it.
Here is the finished assy.
Here it is temporarily mounted in the car.
Here is a cost breakdown.

I think they came out well and it was a fun project. All that is left is greasing them up and mount. I will run with these for a bit and then I plan on tackling TCP's (See below image) design that I've modeled. I'm sure I can make a set cheaper than $450. I will need to make a ball/radius cutter for my lathe first which will require me to get my mill working.
Thanks for checking this out,
Nice.  But definitely not something that can be done without a lathe in your garage or pay for some machine shop work.

There are mixed thoughts on strut rod to frame connections without anything for damping.  I.E. the rubber bushings originally used.  I can see where the new joint provides little or no resistance to suspension movement.  I can also see where the stock rubber bushings dampen shock loads applied to the frame at that location.
Wow nice Job, a lathe makes it easy, unfortunately most of us don't have that kind of tool at our disposal. I have thought it would be a nice addition to my shop, but they are a little cost prohibited. The question is, where is the gain in going to this type of arrangement, as other then being able to move the lower control arm forward or back I don't really see the need ??? Maybe on a Race car, but it seems to be overkill for a street car? Or maybe you just like Cool Shit?

True, having a lathe is a nice thing. I picked mine (an old South Bend engine lathe) up for not too much and I figured it could save me money in the long run by making custom parts and other various projects. My goal here was to show people what can be done (I am not a machinist) and maybe inspire someone to do the same, not to brag about something I have.

As for liking cool shit, well, any honest Mustang owner will tell you that the suspension on these cars is anything but stellar. Or let's just say Ford left plenty of room for improvement. One area would be this strut rod. Ford was cheap and this rod shows it. They almost got it right on the 67 Cougars when they put a jointed rod in but I assume cost stopped this in 68. The reason that it is bad is two fold. One, the rod acts like another spring in the suspension that is unreliable as wear happens. Putting a joint in this bar frees up the suspension and allows the sway bar to translate better to the other side. By doing this it also allows your coil to be the controlling spring. Second, removing the bushings removes some of the slop out of the suspension and also make it more consistent. Rubber bushings compress and when you brake the wheel stops and the car keeps moving forward resulting in tension on the strut causing the rubber bushings to compress. Why does this matter? That compression changes the caster during braking in a turn.

When I had my 69 my goal was to make it handle the best it could without cutting into the frame. This included and custom rack system, front coil overs, my own heim joint Monte Carlo bar (attached at the towers not the fender apron), and these strut rods. It was such a blast to drive this car. I know these mods make the concourse guys cringe, but my car was not a trailor queen, I drove it every day (weather permitting in NY) at least 40 miles.

You do nice work and I understand the benefits of the new designed strut rod.  And I know there are many aftermarket similar designed strut rods. As a mechanical engineer, my only concern is the possibility of long term damage to the frame without anything to dampen applied loads from the suspension to the frame at that location as the tire hits bumps and potholes, etc.
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