Souping-up a cheap seat hinge

We picked up a seat pan off eBay for the Hot-Rod Honda build. The pan is great, real thick and fits just right. It came with a free seat hinge, and the price was right but the hinge left a lot to be desired. For one thing, the tolerances were pretty sloppy with some washers to take up the slack. Secondly, the steel hinge rode on steel shoulder-bolts, which is ok for a little while but that will wear out way too fast for frequent riding. This is a budget build, and it wouldn't seem right to spend more on a seat hinge than the hardtail, so let's see what we can do with this freebie to make it usable.

Here's the patient. The shoulder bolts are very nice with precision shoulders, which will come in handy.



First order of business, if we're going to run bushings we need more room. We hogged the existing holes out to 5/8" on the mill and moved the center a bit closer to the hinge to it didn't punch through the edge. After that, we made a tube to weld in. The ends are bored to 1/2" on the lathe and it's just a bit wider than the existing hinge to leave some room for weld.


Slipped the tube into the hinge and welded around it. After the tube was fully welded we milled out the excess material in the middle until only the bearing reliefs were left. A little grinding and it looks like it was one piece again. Even though the material in the middle gets cut away, the tube ensures that both bushings will be perfectly aligned.




Now that there's enough material for a suitable bushing there needs to be room for a flange on each bushing to take care of side-thrust. The lathe made short work of reducing the width of the center piece by .060" on each end.


Whipped up some nice bushings with flanges on the lathe. Here is the new and improved kit. The end result is that it fits like a glove, and moves much much smoother. Here's a hinge that'll provide years of solid riding and didn't break the budget on this build.