04 May 2020

Bolt Extractor to Remove Stripped Transmission Support Bolt on BMW E39

I broke a support brace bolt, while replacing my old transmission mounts on the E39. The bolt was broken at the head, and the threaded shank was left in the hole. I heard it snap and felt sick to my stomach. It was the last bolt to be removed to the brace and I didn't know what to do.

I looked online and apparently, breaking transmission support brace bolts is common. They are exposed to road salt, and get rusted out. Drive train components last for years before maintenance, so these bolts don't get taken out often.

The solution:
  • Extract the broken bolt with a screw extractor. 
  • If extraction doesn't work, drill it out. 
  • Rethread with tap and die, if female threads are stripped
  • Helicoil, if cutting threads doesn't work with tap and die

Broken bolt and stuck screw
I purchased the Werkzeug damaged and stripped screw extractor set and a  a Gearwrench Ratcheting Tap and Die set as well. There are 22 pieces and it comes with an magnetic extension bit holder and socket adapter.



I placed the bit holder in my drill, and picked the smallest driller. I started drilling, and had some difficulty establishing a clean hole to use the bit. I lowered the drill speed and alternated between driller sizes. I was really skeptical at first, because the bits are so small. I questioned myself, if I was doing this right at all, and if this would even work. I pressed on, out of desperation.

After 25 minutes of drilling, I finally got a good clean hole and put in the extractor. I pressed the trigger and could see the screw turning a little but it stopped. So more drilling, with a larger driller. I stepped up the extractor to #6 and the broken screw finally came out. I was elated and so happy.


Broken screw with extractor tool

Broken screw removed
I cleaned up the threads with a tap and die, removed and replaced the old transmission mounts, and put in a new support bolt into the brace.

The $20 extractor kit saved me a trip to the shop. Every do-it-yourself mechanic needs to have one of these. It is such a lifesaver, especially in tight spots where cutting the bolt is not feasible.

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