By Christopher Gosnell
In the state where I live - Pennsylvania - we not only have emissions inspections, we also have safety inspections. Safety inspections sound like a good idea - who doesn’t want to be safe? - but in a some cases you get dinged for something that is questionable at best. There is no use arguing with the inspector. Such is the case with my 2001 PT Cruiser.
The dealer inspected my car and told me that the control arm bushings were cracked and needed to be replaced. He offered to do it for me for about $450 or so. I declined his offer and started the work myself. I found that I could buy brand new control arms (bushings and all) from NAPA for less than the cost of having them push out the old bushings and installing new ones, so I bought new arms. As a bonus the new arms also included new lower ball joints.
The fun started when I tried to break loose the old control arm bolts. Some of them came out without much problems, which is amazing for an 10+ year old car, but one control arm bolt on each side of the front suspension was vertical, right through the sub frame and into the main frame of the car. Of course the nut was mounted somewhere inside the frame and could not be seen. As I tried to loosen the bolt, I felt the nut give and start to turn. Great! Now the nut was loose somewhere inside the frame and could not be disassembled.
The make a long story short, I had to cut the heads off of the control arm bolts, lower the suspension sub frame (including the steering rack) off of the car to expose the frame where the bolts (now headless studs) were protruding. After cutting out the frame around the stud, I extracted the nut. I looked like a tee nut with rounded ends and it was an interference type thread design that was placed loose in a pocket that was welded inside of the frame member. There is NO way to get at this nut any other way than cutting the frame. Looking at the pocket the nut was located in, it was so loose that with a little bit of effort the nut deformed the pocket as it twisted.
I then proceeded to weld up the flats on the side of the nut, taking up about half of the clearance allowed in the pocket. I then re-welded shut the frame around the area for the nut, re-assembled the sub frame with new bolts, and finished the rest of the job.
Thinking about this for a while, I thought that the nut should have been made approx 2X or 3X longer than it was wide to keep it from spinning in the pocket, not 1.2x longer as it was. Oh, and after checking, I couldn’t see any cracking on the control arm bushings, but I passed inspection…
Christopher Gosnell is an engineer (small e) who grew up in Chicago, Ill. (go Bears!). As a kid, he would go to work with his father traveling to restaurants to repair their kitchen equipment (ovens, fryers, dish machines, whatever). Christopher now works for a manufacturer of aerospace and medical components, designing processes, tooling, and fixturing for forging and machining. His duties also focus on FEA analysis of the bulk forming processes and classic structural analysis.