I took the inner door panels off in preparation for trying to adjust the windows. The door underneath is in rough shape. Most of the screw holes are stripped and the filler is stripped as well. Both access panels appear to have been glued on I have no idea what the black tar-like stuff is in the middle. Any recommendations on cleaning this up and repairing the stripped screw holes? The passenger side is in similar condition.

 

I had the same issue with the doors on my '60. Put squeeze nuts in the stripped out holes ane replaced the screws with machine screws.

 

The access panels were sealed with strip dum-dum , I ground my screw holes out and put 2 layers of fiberglass over them , then redrilled. Do a search here and you will find many ways to fix em. The holes were sealed with tar and some kind of wax paper to keep water from getting on the door panels. Think about it.

 

Do you mean Riv nuts?? That would be my recommendation too... Some of the softer aluminum ones

 

The doors on our '60 were in similar shape with lots of bad screw holes. I used rivet nuts around the perimeter for the panel retraining screws and I made "nut plates" out of 1/8" x 1/2" aluminum bar stock drilled and tapped for 8-32 machine screws and attached inside the door with pop rivets to retain the two access panels. As you can see, our doors had lots of black "stuff" spread around as well.
John Hinckley (JohnZ) introduced many of us to the use of rivet nuts back in the day!

 

Also, 'nut plates' designed to rivet into place are a very common part used in aircraft and are available in all different sizes from aircraft supply houses.

 

Yes, my bad

 

Would you recommend sanding down the current filler and patch the fiberglass for a smooth, clean surface before installing the riv nuts? If so, what tool would you use for sanding, powered orbital sander or just a sanding block?

 

I agree with 61. get the surface even with polyester resin and mat first. Locate the holes with a trial fit. Then use aluminum rivnuts. This repair will last forever.

Joe

 

A 90 degree die grinder with 2 or 3" wheels.... I see Mid Year mitch uses alot of 36 grit to start with but I would be more of the mindset to start with 60, 80 or even 120... You can always change the disc ......