I have to install the doors back on my '68 1800 - the threads appear to be fine.

I would like to clean up the threads in the door hinges which are still on the car.

Do you know what size these threads are?

BTW - I have posted this car on BB for sale without any interest.

The PO stripped this car, it is not even a basket case but to me, the body looks pretty good and I have amassed a lot of the needed parts.

I'm pretty sure the bolts that hold the door hinges to the door are 5/16" UNF(fine) and IIRC the ones holding the door hinge to body are 3/8", but I'm not sure of the thread pitch.

Just in case you didn't notice, the bolts that hold the hinges to the door are special. The tip comes to a point, but what's most critical about the bolts is the underside of the head which isn't flat but has a cone shape and the holdes in the hinges have countersunk hole so it's tapered like some wood screws.
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Eric
Hi Performance Automotive Service (formerly OVO or Old Volvos Only)
Torrance, CA 90502
hiperformanceautoservice.com or oldvolvosonly.com

Thank you Eric for the heads up.

I did not have the bolts, but I bought 20 pounds of 1800 hardware on eBay, and I figured out which ones were for the doors. I did notice the pointed bolt tips, but not the cone under the heads

I cleaned the bolts with an old bench motor with a wire brush that belonged to my father - the motor was a used one that my father had on his bench 70 years ago - an old GE motor that I added a new cord to and plugged it in on my patio ( In case it caught on fire or exploded!) It runs silently and I cleaned a lot of hardware with it.