The last couple of nights I have been doing a couple of seat post rebuilds and ended up with a few questions. In this photo is a view of the upper end of 1936 to 1957 seat posts. I was curious as to when the seat post with the threaded on top was used. I had always assumed that the top was silver soldered to the tube. I have a theory on this but will hold off so that I can hear what you all have for ideas.
![](http://i243.photobucket.com/albums/ff187/JerryWieland/Seat%20Posts/1936%20to%201957%20posts/DSC00216_zpscdajhmlk.jpg)
I happened to have a junk post so I tried to unscrew it with no success so then I put the top of the post in the lathe and made small successive passes until I could in fact see the braze. You can actually see the braze line in the center seat post in the above picture.
![](http://i243.photobucket.com/albums/ff187/JerryWieland/Seat%20Posts/1936%20to%201957%20posts/DSC00218_zpsmhihv4l4.jpg)
The second question pertains to when did they change the chamfer on the top from a rounded chamfer to a straight 45 degree chamfer. I checked my original 47 EL and 48 FL and they both have the rounded chamfer.
![](http://i243.photobucket.com/albums/ff187/JerryWieland/Seat%20Posts/1936%20to%201957%20posts/DSC00213_zpsy0qjckio.jpg)
The third question is when did they change the fitting that screws into the bottom of the post and acts as a guide for the spring rod. There is actually a third one that has no provision to be unscrewed with a tool but every post I had with this type of rod guide was for a later swing arm seat post.
![](http://i243.photobucket.com/albums/ff187/JerryWieland/Seat%20Posts/1936%20to%201957%20posts/DSC00216_zpscdajhmlk.jpg)
I happened to have a junk post so I tried to unscrew it with no success so then I put the top of the post in the lathe and made small successive passes until I could in fact see the braze. You can actually see the braze line in the center seat post in the above picture.
![](http://i243.photobucket.com/albums/ff187/JerryWieland/Seat%20Posts/1936%20to%201957%20posts/DSC00218_zpsmhihv4l4.jpg)
The second question pertains to when did they change the chamfer on the top from a rounded chamfer to a straight 45 degree chamfer. I checked my original 47 EL and 48 FL and they both have the rounded chamfer.
![](http://i243.photobucket.com/albums/ff187/JerryWieland/Seat%20Posts/1936%20to%201957%20posts/DSC00213_zpsy0qjckio.jpg)
The third question is when did they change the fitting that screws into the bottom of the post and acts as a guide for the spring rod. There is actually a third one that has no provision to be unscrewed with a tool but every post I had with this type of rod guide was for a later swing arm seat post.
![](http://i243.photobucket.com/albums/ff187/JerryWieland/Seat%20Posts/1936%20to%201957%20posts/DSC00216_zpsdcaa6myl.jpg)
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