Posted by Mark in Santa Cruz [220.127.116.11] on Wednesday, November 18, 2020 at 14:23:05 :
In Reply to: Re: 71 W200 Door Hinge Rebuild posted by PwrWgnDrvr [18.104.22.168] on Wednesday, November 18, 2020 at 00:49:50 :
Morning, I am not sure if you are disagreeing or are surprised that the center hinge is supposed to rotate about the pin but here are my observations for anyone interested….
I took off a hinge from a donor door and was able to drive the pin out. I cleaned the pin with a wire wheel and ran the correct size drill bit down the hinge center hole with some WD-40 to clean the rust then sprayed everything with brake fluid. I didn't take any metal off of either piece, just cleaned off dirt and rust.
I inserted the pin in the center hinge and it spun freely. I doubt that the rust that I removed was enough to cause the pin to spin so much, rather it appears to be how the hinge was designed to work.
I found oil grooves on both flat edge faces of the hinge center. I read somewhere that these oil grooves are intended to keep the pin lubricated and moving freely.
I also noticed that the pins are splined at the top. Generally, splines in bolts or pins are used to lock the bolt or pin in place by gripping the surrounding material or by meshing with grooves in a mating piece. Assuming the pins in my hinge are original, the splines at the top of the hinge would suggest that pin was designed to ‘lock’ into place with the outer bracket.
Lastly, I suspect the reason that you never seen a hinge rotate around the center hinge is due to age, lack of lubrication and the relatively thin gauge metal that the outer bracket is made from when compared to the pin and center hinge. Once the pin rusts in place, the outer bracket is by far the weakest link.
Just my .$02
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