Ok, I've searched the forum for a thread on this, with no luck. I hope someone has advice on this because it seem like would be a common problem.

During removal of the '79s taillights, I was left with 2 screw on one side and 1 screw on the other. I've tried epoxy, twice, and gorilla glue neither were strong enough. Is there some other way to get the screws back on the light fixture?

Hi Hawaiispiderman

I plastic welded them back in with a solder iron and some xtra plastic tabs of similar plastic.
Has been 4 years and still holding

Thanks for the tip Drummond. Just to clarify, only 1 of the 5 screws actually broke out of the plastic. The rest broke off at the bottom nut. These I cutoff and ground flat and am trying to add screws on top of what's left.

Did your screws break out of the plastic completely?

I fed a machine screw with washer in each hole and then ran a nut and washer down the screw. The trick is getting the screw in place from inside the lense to put the nut on. I used wire to fish the screw into place.
A blob of epoxy after getting the nut snug stopped any rotation.

Oh and i used ss machine screws to prevent future corrosion.

Good luck

Dinghyguy with the still too small garage

I heated the broken screws with a soldering gun to remove the broken head from the plastic and then ground down the heads on some stainless steel machine screws to match the original size leaving them rough and plastic welded them back into place.

Save as much of the plastic that comes off when you remove the original machine heads from the plastic lens to use as filler when you weld in the replacements and you may need little to no plastic welding rod. Be careful to not overheat and carbonize the plastic or it will get brittle and loose strength.

I may use a few dabs of super glue to clamp the parts into alignment so they do not move while welding. My go-to source for plastic welding rods was Harbor Freight however they stopped selling the assortment packs of welding rods and have offered no replacement however Graingers does stock the rods as do many other internet stores.

I forget if ABS or Polypropylene welding rod was the best match for the plastic in the lenses.

to remove the original broken stud, I use a Dremel type tool with a 1" cut off wheel. I cut off a side of the nut holding the broken stud in the plastic. This is best don with 2 people one grinding and one dripping water on the nut so it doesn't over heat and melt the plastic.
Once the nut is cut off the stud will fall into the lens and can be fished out
I could not find replacement studs with the square head used in most of the light assemblies. So I use hex head replacement bolts I think they might be 5 mm
Then I fish a #22 or smaller wire into to studs hole and out the closest light bulb hole, Strip about 3/8 inch of insulation off the end that came out of the light bulb hole. Tin it with solder. Now stand the replacement stud on it's head. clean the tip where the nut starts on with wire brush and file. Use solder flux and tin the very end of the stud being careful not to get solder in the threads. Solder the tip of the wire to the tip of the stud.
Pull gently on the wire while guiding the stud with a finger inside the the plastic lens. Pull the stud through the hole. Slide a flat washer followed by a nut down the wire and finger tighten the nut all the way. Remove the pull wire. Using 2 more nuts double nut the end of the new stud to keep it from turning while the retaining nut is is fully tightened with a wrench. Be sure the stud is properly seated before tightening.

Hope this makes sense. I have replaced at least 20 studs using this procedure. Depending on the condition of the plastic area around the stud I may or may not use JB Weld in the area.
If you would like me to make the repair for you my email is flyme194@gmail.com

exactly and much better said than i did. Some of them i could install by winding the wire around the thread and then using the wire to hold align push the bolt out from inside until i could grab the bold and screw on a nut.

cheers
dinghyguy

Thank you all so much. Seems the method is similar. I'm new to plastic welding, but am sure it won't be too difficult. Can I use my soldering iron instead of buying a plastic welder? They look the same, but not sure about temps or tip.

The whole "fishing the bolt" part seems to be the most challenging.

HawaiiSpiderman wrote:Thank you all so much. Seems the method is similar. I'm new to plastic welding, but am sure it won't be too difficult. Can I use my soldering iron instead of buying a plastic welder? They look the same, but not sure about temps or tip.

The whole "fishing the bolt" part seems to be the most challenging.

If the bolt will slip out the back and a new one can be slipped into its place then that is also a viable option. Yes a soldering iron can be used however extreme caution has to be exercised as the temperature control is not accurate enough even on a gun with a two heat trigger. A soldering station with a infinitely variable heat control would be better and you would start low and work your way up to the melting point so the plastic will melt without burning. On old plastic the jump point between melting and burning can be quite small.