DIY! Adjustable Strut Rod Attachment Point

[71_Stang]

Those of you that have looked up how to built DIY adjustable strut rods have probably seen this website.... http://dazed.home.bresnan.net/adjustable.

But, much to my disappointment, the website took down their instructions on the strut rods because of concern over the hardware used to attach the rod to the frame.

I never really loved the design to begin with because it pushed out the pivot point 2"-3" from the original factory placement. So I've been working over the past few weeks to design a setup that would be cost effective and would keep the factory pivot point. Here is my design:

The material used is 7075 aluminum, which is lighter than steel and has a higher tensile strength. They are designed to fit inside the bushing hole in the frame and a standard 1.50" rod end head diameter fits and moves up/down freely. It allows the pivot point to be .5" behind the face of the frame.

The ears extend .75" past the opening and two 3/8" bolt holes are drilled to mount it to the frame (holes would have to be drilled into the frame).

I had a machine shop quote it and to make just two was going to be ridiculous. But the price goes down with the more copies made (apparently most of the cost is setting up the CNC).

If 10 are ordered (4 cars + mine), the cost is 50 per unit ($100 total)

If 20 are ordered (9 cars + mine), the cost is $30.00 per unit ($60 total)

If enough of you are serious about buying these, let me know and we can get a pretty good deal. Or if you have any suggested tweaks to the design, let me know!

 

[Jeff73Mach1]

Why in the world would you bother to CNC a part that is a tube with a hole drilled through it and a plate welded on the end? You have $5.00 worth of material (It would be scrap in most fabrication shops and sent to the recycler.) It seems like they are quoting you a price to cut it from a single piece of billet. Again-Why? Answer-to be able to charge you a bunch of money!

Find someone that does TIG welding and let them build them by hand. CNC is overkill for such a simple project.

Also, Aluminum is lighter than steel, but it has less plasticity and once over stressed, it does not recover like steel does.

A good grade of Chrome moly steel would be cheaper, easier to work with, would not need anodizing or powder coating to get it to hold paint and I would bet you dollars to donuts, would ultimately be stronger. (And cheaper to manufacture)

 

[71_Stang]

Find someone that does TIG welding and let them build them by hand. CNC is overkill for such a simple project.

The diameter of the frame hole is 1.40"; tube is not made to this O/D size (to my knowledge). Size is key because you want this tube to fit snugly into the hole to prevent play. Also, you probably can't see it but the inside hole inside the tube is elongated to fit the heim joint vertically and to provide a flat surface for misalignment spacers. If you did find a tube that was 1.40" or if you ground down a 1.50" tube to this diameter, you would never find tube wall that would work with a 5/8th hiem.

Believe me, I ran though several "homemade" bracket ideas but the hole size/hiem size prevents anything mounted inside the frame without a elongated opening.

Welding brackets to the frame was never an option. One of my goals was to make a bracket that could be removed from a car, to go back to factory setup at any point.

Why in the world would you bother to CNC a part that is a tube with a hole drilled through it and a plate welded on the end? You have $5.00 worth of material (It would be scrap in most fabrication shops and sent to the recycler.) It seems like they are quoting you a price to cut it from a single piece of billet. Again-Why? Answer-to be able to charge you a bunch of money!

To answer your question "why aluminum?" -

Aluminum does carry higher material costs but is a softer material so machining costs are cheaper than steel. This part is actually a few dollars cheaper in aluminum than cold rolled steel.

 

[Jeff73Mach1]

I didn't mean welding to the frame, only the plate to the tube section of your design.

It is still a relatively simple part (yes I saw the elongated inner portion)

take a piece of round bar and turn it on a lathe to the proper exterior dimensions. (You would probably want to turn down multiple parts at one time and then cut them apart before continuing the machining) Use a mill to cut the elongated hole. A machinist that can't do this is not much of a machinist. Cut your end plate and weld it together.

To use a two piece design, I would change the design a bit to leave a lip on the "tube" portion and I would cut a groove in the "plate" to fit together as an interference fit and then weld it together. This way the lip and register make a mechanical bond that will stay together even if the weld were to break. Remember this part only needs to be a bit stronger than the heim joint you intend to use- excessive strength beyond that is wasted.

And if you wish to do it in aluminum, it is the exact same.

 

[71_Stang]

I didn't mean welding to the frame, only the plate to the tube section of your design.

It is still a relatively simple part (yes I saw the elongated inner portion)

take a piece of round bar and turn it on a lathe to the proper exterior dimensions. (You would probably want to turn down multiple parts at one time and then cut them apart before continuing the machining) Use a mill to cut the elongated hole. A machinist that can't do this is not much of a machinist. Cut your end plate and weld it together.

To use a two piece design, I would change the design a bit to leave a lip on the "tube" portion and I would cut a groove in the "plate" to fit together as an interference fit and then weld it together. This way the lip and register make a mechanical bond that will stay together even if the weld were to break. Remember this part only needs to be a bit stronger than the heim joint you intend to use- excessive strength beyond that is wasted.

And if you wish to do it in aluminum, it is the exact same.

I will ask if they can do what you mentioned. If so, it would be cheaper than routing the design from one block. Hopefully!

 

[71_Stang]

Priced it out the job to mill and turn a 1.40" rod with a .75" slot and it's going to run about $35 a piece. Once you factor in the plate mount, it will be $100 total.

Of course this is for a single car, so it's probably the cheapest option. Unless others were interested in the aluminum design out of one piece.

 

[Jeff73Mach1]

I hope I didn't come off as being critical of your plans.

I have a question-While I generally understand the idea behind the strut rod needing freer articulation to allow the front suspension to work better- I am curious as to what effect the pivot point change might make.

You are trying to keep it in the stock location when the stock part didn't pivot in the same manner. Does this matter? Does the pivot cause the lower control arm to deflect forward or backwards?