C-cab Door Hinge Pin Repair/Replacement
by Kevin Airth
I had to repair both of my lower door hinge pins and found out a few things. Some tips have been posted to the list but contain errors that might cause more destruction than repair. The hinge pin is stationary and the door rotates around the pin. So if your hinge rotates but either end of the pin turns you have a sheared hinge pin, which is the first thing to seize as the hinge turns to rust. This will work for a long time but the door gets sloppier as it wears more. One of my pins was broken in 3 places! The head of the pin is on the topside of the hinge and underneath has serrations that dig into the hinge frame to prevent rotation. This puts all the force on the pin body as rust starts to lock up the hinge. So your pin most likely will be broken right at the serrations on the top portion. There are reinforcing washers on top and bottom of the hinge frame. They ARE NOT attached to the pin. They are spot welded to the hinge frame and are stationary. The bottom of the pin is not deformed from the factory. There is no need because the pin is locked in place from the top by the serrations on the pin.
To remove the broken pins is the battle. If enough of a stub is sticking out the bottom try and grab this in a vise as tight as possible. Heat the cast portion of the hinge with a torch to cherry red. With gloves on, try and rotate the cast portion of the hinge back and forth just a little bit. If you can get it to move, then try to rock it back and forth, while pulling the pin out the bottom of the hinge. If the hinge is frozen and will not turn then you must try and pound out the entire hinge pin from the bottom. Be sure and support the hinge frame when pounding because the frame can be bent from hammering. Don't pound from the top!! This will only make it tighter! You can grind the head off if needed but be careful and don't tear up the reinforcing washers. Remember it's serrated at the top so even with the head removed it will be much harder to pound it out from the top to the bottom. Always work from the bottom!
The pin part number is 652522 and it's 5/16" diameter X 2 3/32" Long. Studebaker engineered these pins much better than the new replacements!! They machined lubrication channels down the body of the pin and a center indentation that lines up with the lubrication hole drilled in the hinge! Not available that I could find. I recommend using a modern pin of 11/32" diameter. These are very common and I got mine from the local parts store. Help part #38410. .342" X 3.57" long. They are available from GM also. Part #15598845 or #20046147 about $2.50 to $5 each depending on where you find them. The first GM part number has the correct 1z2" OD head while the others use a larger 9/16" diameter head. The 11/32" pin O.D. is only 1/32" bigger in diameter so when you drill the hinge out it should clean up all the wear and rust. If you really want to do it right, Stainless Steel pins are available from Auveco, Part #17344. Clean out the lubrication hole before assembling to make sure you can lubricate the pins after installation. Try to use a drill press to keep the holes straight. Then drive the pin in until the head is flush with the reinforcing washers. Now cut the end off where you want it. If you want to mushroom the cut end over with a hammer you can but the pins are pretty hard.