Control Arm Rod Modification

[LittleRed]

Greetings all!

They say that “Necessity is the mother of invention”. I have a Reatta that I recently picked up and the control arm rod was rusted off at the frame. I read every posting I could find on how to repair it and did a lot of research on my own. The solution I came up with is pictured below. Now I know that some of you are going to scream “Nooooooo!” but I did what I thought I had to do. I took careful measurements and cut the rod so that my completed work would be 10 5/8” from the control arm. I then cut about ¾” m20 2.5 threads on the rod (I used m20 because it was the closest to the diameter of the rod and cutting those threads was a “bear”). Then I screwed on a m20 hex coupler to which I screwed in a m20 to m12 adapter on the frame side. From there I was able to use a m12 threaded rod to complete the installation.  I know that it is not original but I was looking for a reasonable cost solution. It seems to work fine, I will have to wait a while to see how it does on the long haul.

There you have it, take it for what’s its worth. 

[2seater]

I have a pair of lower arms, one with a broken end, and I was thinking of a welded repair. Somewhat similar to the threaded one shown, but just a plain welded sleeve with a threaded rod on the extension, probably stainless steel material. The only suggestion I can offer is either a jam nut on the coupler or perhaps a tack weld to prevent an possibility of rotation or push/pull on the new threads. Overall, I like the idea

[DPS.01]

2 hours ago, LittleRed said:

“Necessity is the mother of invention”

Always…

[Ronnie]

Is it just the angle the photo was taken or is the coupler threaded on the rod a little crooked? If it is crooked I don't think it's likely to hurt anything, but it could put a lot of side load on the threads if you had to slam on the brakes in a panic stop. Just to be on the safe side I think I would tack weld it onto the rod if it's crooked, even if you have to take it to someone to do it.

[Ronnie]

BTW, I didn't mean my post to sound critical. I think it's a good solution to fixing that problem. I would do the same if I needed to.

[LittleRed]

2seater and Ronnie, thank you so much for your thoughts! I considered just welding a pipe or sleeve to the end but was unsure about the strength of just welds given the movement of the arm. I think both of you are right in putting some tack welds on it just to help relieve some of the pressure on the threads. I did weld the threaded adapter on the other end in place. Ronnie, no offense taken. With this being a critical support structure, it needs to be sound! As for the bend, it is an optical illusion because it is straight.