So I go to replace the license plate screws (rear tailgate) no big deal right?? Wrong; they hadn't been touched in years.
One screw which was likely stainless came out without much effort, just a touch of penetrating oil, but the other one had welded itself to the nut. Looking back on it I seem to recall grabbing what I had on hand, what fit, but knowing it was a POS screw, probably figured I'd replace it, but then forgot about it, 15-20 years ago. Every year just putting another date sticker on the old plate.
I first tried penetrating oil (a few different types) for a few days from both outside and inside the tailgate cavity, nope, head snapped off flush with the sheet metal.
Tried Speed Outs/Easy Out bits from outside and inside the tailgate cavity, nope. Couldn't get a straight on shot to the shaft from inside however.
Then tried the double nut method often used to remove studs, this might have worked better if I had a thinner wrench, but nope.
Then cut a slot in the broken shaft using a mini-hacksaw blade in an attempt to turn the shaft from the inside using a screwdriver, nope, ears snapped off.
Tried heat from a mini-torch, nope, started to melt the factory sound deadening even with the use of a couple of fiberglass sheets. Tried heat from a soldering iron, took the tip out of the iron and hung the barrel of the iron on the shaft of the screw inside the tailgate cavity being careful not to overheat the painted surfaces on the outside using a garden hose on mist; heat, cool, heat, cool. Nope
Tried to turn the shaft working from the inside using vice grips, not much room to work, again, moved a couple degrees maybe.
All along was constantly spraying more penetrating oil on the screw shaft. Even tried White Vinegar overnight soaked into a paper towel I stuck on the shaft in an attempt to dissolve the rust (which did work on the exposed threads). Next applied gelled phosphoric acid to the threads for 30 minutes.
Then drilled a small hole in the shaft from the outside, then a larger hole, then larger in an attempt to weaken the shaft threads hold on the nut.
Finally cut off the remaining shaft in the tailgate cavity and saw the hole I had drilled was past the nut.
All the above attempts were trying to save the original threads of the factory nut but then decided to go for broke and my last attempt I used a 5/32" drill bit into the (off-center) hole I had drilled earlier.
Heard a screeech and the drill bit went all the way through and when I looked at the drill bit on the tailgate cavity side I saw the remaining short section of threads of the screw shaft stuck on the end of the bit.
Success!!
Followed that with M6 x 1mm cutting tap to clean out the threads (didn't have a clean out tap in that size) and that did remove a bunch of rust. After cleaning the threads with acetone gave the thread/nuts a touch of primer and paint (using Q-tips) to stop flash rusting. Figure once the new screws go in the threads will scrape out most of that paint but some will be left behind which might slow down rust in the small non-contact areas.
Point is: doing some license plate screw PM could save you a few hours of pain in the arse work in 100'F+ outdoor temps when the license plate screws weld themselves to the factory nuts in the tailgate.
FWIW I'll be installing stainless steel screws (possibly the tamper resistant type) with either a thread sealer or anti-seize possibly also with an O-ring to help prevent water from getting into the threads.
Maybe these:
www.mcmaster.com
In hindsight (and what was suggested by others) it would have been quicker to just drill out the broken shaft from the beginning then tap both nuts to a larger thread.
Snapped off screw:
Attempt with a Speed Out/Easy Out from inside but couldn't get directly in line with the shaft due to space constraints (didn't get photos of multiple attempts on the broken side):
Next photo shows gelled phosphoric acid on the threads attempting to dissolve the rust:
Double nuts wrenching on the bottom nut after tightening them both firmly together:
Mini-hacksaw blade used by hand to cut a groove into the shaft. Corner of flat file was used first to start the groove:
One screw which was likely stainless came out without much effort, just a touch of penetrating oil, but the other one had welded itself to the nut. Looking back on it I seem to recall grabbing what I had on hand, what fit, but knowing it was a POS screw, probably figured I'd replace it, but then forgot about it, 15-20 years ago. Every year just putting another date sticker on the old plate.
I first tried penetrating oil (a few different types) for a few days from both outside and inside the tailgate cavity, nope, head snapped off flush with the sheet metal.
Tried Speed Outs/Easy Out bits from outside and inside the tailgate cavity, nope. Couldn't get a straight on shot to the shaft from inside however.
Then tried the double nut method often used to remove studs, this might have worked better if I had a thinner wrench, but nope.
Then cut a slot in the broken shaft using a mini-hacksaw blade in an attempt to turn the shaft from the inside using a screwdriver, nope, ears snapped off.
Tried heat from a mini-torch, nope, started to melt the factory sound deadening even with the use of a couple of fiberglass sheets. Tried heat from a soldering iron, took the tip out of the iron and hung the barrel of the iron on the shaft of the screw inside the tailgate cavity being careful not to overheat the painted surfaces on the outside using a garden hose on mist; heat, cool, heat, cool. Nope
Tried to turn the shaft working from the inside using vice grips, not much room to work, again, moved a couple degrees maybe.
All along was constantly spraying more penetrating oil on the screw shaft. Even tried White Vinegar overnight soaked into a paper towel I stuck on the shaft in an attempt to dissolve the rust (which did work on the exposed threads). Next applied gelled phosphoric acid to the threads for 30 minutes.
Then drilled a small hole in the shaft from the outside, then a larger hole, then larger in an attempt to weaken the shaft threads hold on the nut.
Finally cut off the remaining shaft in the tailgate cavity and saw the hole I had drilled was past the nut.
All the above attempts were trying to save the original threads of the factory nut but then decided to go for broke and my last attempt I used a 5/32" drill bit into the (off-center) hole I had drilled earlier.
Heard a screeech and the drill bit went all the way through and when I looked at the drill bit on the tailgate cavity side I saw the remaining short section of threads of the screw shaft stuck on the end of the bit.
Success!!
Followed that with M6 x 1mm cutting tap to clean out the threads (didn't have a clean out tap in that size) and that did remove a bunch of rust. After cleaning the threads with acetone gave the thread/nuts a touch of primer and paint (using Q-tips) to stop flash rusting. Figure once the new screws go in the threads will scrape out most of that paint but some will be left behind which might slow down rust in the small non-contact areas.
Point is: doing some license plate screw PM could save you a few hours of pain in the arse work in 100'F+ outdoor temps when the license plate screws weld themselves to the factory nuts in the tailgate.
FWIW I'll be installing stainless steel screws (possibly the tamper resistant type) with either a thread sealer or anti-seize possibly also with an O-ring to help prevent water from getting into the threads.
Maybe these:
McMaster-Carr
McMaster-Carr is the complete source for your plant with over 595,000 products. 98% of products ordered ship from stock and deliver same or next day.
In hindsight (and what was suggested by others) it would have been quicker to just drill out the broken shaft from the beginning then tap both nuts to a larger thread.
Snapped off screw:
Attempt with a Speed Out/Easy Out from inside but couldn't get directly in line with the shaft due to space constraints (didn't get photos of multiple attempts on the broken side):
Next photo shows gelled phosphoric acid on the threads attempting to dissolve the rust:
Double nuts wrenching on the bottom nut after tightening them both firmly together:
Mini-hacksaw blade used by hand to cut a groove into the shaft. Corner of flat file was used first to start the groove:
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