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So I was replacing my rear upper control arm (passenger side) for my 1995 Acura legend today, and I was trying to take out the bolts that go into the subframe. One of them was hard to turn, so I got a jack handle for more torque and started on it again. Then it snapped and I thought that the bolt had broken... when I tried to pull the arm out though the bolt wouldn’t budge, and I realized what happened: the welded nut inside the subframe had broken off, and the bolt didn’t come out of the nut so it’s free spinning and stuck there!!! (The bolt came out a little though so I have some play). Now I was considering some options...

  • Cut the bolt and push the rest of it inside the frame and try force a bigger one through(and weld the upper arm to the frame because I’m not replacing it again)
  • Cut the bolt to get it out, push the rest through, and then cut the subframe peel it back and then access that way to put a new nut on the back and tighten it like that, then put the subframe back and weld it up(but I don’t know where to cut exactly)

What do you guys think??

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  • What do you mean weld the control arm to the frame? It has to be able to move. IMO you should gain access and put a new nut and bolt in.
    – Ben
    Feb 14, 2018 at 16:02
  • Well there’s a metal part that goes through the bushing, and the metal part bolts to the car, so I was thinking weld that to the subframe after forcing an oversized bolt in
    – sjfklsdafjks
    Feb 14, 2018 at 16:04
  • Also would cutting the subframe be detrimental to the structural integrity of the car itself? How big a hole do I cut?
    – sjfklsdafjks
    Feb 14, 2018 at 16:05
  • The sleeve is bonded to the bushing usually. A hole some thing like 5”x5” or whatevers feasible would be fine just weld the cutout back in place when you’re done.
    – Ben
    Feb 14, 2018 at 16:08
  • Update: I was removing he bolt today via drilling it out and pushing the rest into the subframe when I realized that the subframe was actually a few good inches thick in that same spot where the bolts go, and it’s not threaded because the current bolt threads into a nut at the back not the subframe... so I decided to drill the existing bolt out and tap the hole in the subframe with an m10 tap and sink 2 hardened bolts in it, and my final plan is to weld over the static part of the control arm since I’m not replacing it and that should hold better than oem!!! Any flaws to my plan?
    – sjfklsdafjks
    Feb 15, 2018 at 11:18

2 Answers 2

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I encountered a similar problem some time ago changing a wishbone on a Mk3 Golf. The solution was to replace the subframe with a good second hand unit purchased cheaply from a vehicle breakers yard which was thoroughly cleaned and painted before fitting to prevent corrosion.

Depending on what access is like, you could potentially cut an opening in the subframe as it sits and try and get either a set of grips on the not-so captive nut or a spot of weld onto it to allow you to unscrew the stuck bolt. Once removed you could weld the captive nut back in place and then weld up the hole you'd cut into the frame.

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  • So a hole 5x5 as Ben said wouldn’t be critical to the structural integrity of the rear end? That would be perfect as I could just put a whole new nut on there
    – sjfklsdafjks
    Feb 14, 2018 at 16:12
  • If you seam weld up any hole that you create with an equivalent thickness metal, there will be no issue.
    – Steve Matthews
    Feb 14, 2018 at 16:14
  • Mig weld is good enough also right?
    – sjfklsdafjks
    Feb 14, 2018 at 16:16
  • Yes, MIG will be perfect for this application.
    – Steve Matthews
    Feb 14, 2018 at 16:16
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    As long as it’s a decent weld, not some of the “bird droppings” that some call welding - no offense intended...
    – Solar Mike
    Feb 14, 2018 at 18:22
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If possible.. try drilling a hole.. big enough for a large screwdriver and a replacement nut to fit through.. in the side of the subframe, in front of OR right next to the area where the captive nut is spinning.

Stick the large screwdriver through the hole using the hole itself and the flat of the screwdriver as a lever to jam the captive nut to stop it spinning, whilst you unscrew the bolt.

If successful remove the captive nut & replace the it with a suitable one, using a telescopic type magnet to remove old nut & position new one if necessary, then weld the hole back up.

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