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Why?
Why not just use springs and call it a day? I could not bring myself to put a spring seat on a Buell based chopper. Probably just me but springs look good on a nice Trump, Pan, Knuck, etc…
Benefits?
Fully adjustable
No lateral movement
Cool and functional
What’s the big idea?
Basically you create a simple closed air system composed of a small air tank welded to your frame and two little air bags connected to the air tank via thin plastic tubing. No compressor, wiring and such. Here’s the top view:
Parts?
You can buy the air seat set up for mucho $$$ but that’s no fun.
Here are the parts you need to make your seat. The items in ( ) are what you’ll see in my build.
Seat pan (BaasMetalcraft)
Seat hinge (Fab Kevin)
Air bladders (HD police road king)
Air fittings (HD)
Air tubing (HD)
Metal tubing that matches the diameter of your frame (Home Depot)
1/8” NPT bungs (BunkKing.com)
Schrader valve (HD)
Flat bar (McMaster Carr)
Round stock (Home Depot)
1/8 NPT T fitting (Home Depot)
1/8 NPT fitting (Home Depot)
How to?
1. Mock up seat location on bike.
2. Mark where the front of the seat hinge will mount to frame.
3. Mark where the rear of the seat hinge will mount to seat pan.
4. Ensure you have enough room between your frame rails to accommodate the air bladders.
5. Mount air bladders to flat bar.
Inflated air bladders mounted to flatbar
I had the stock HD air tank so it helped with the mock up. The bladders shrink when filled with air.
6. Mock up again using the air bladders mounted to flat bar. Ensure the proper vertical placement of the air bags so you get the right seat angle. Your seat pan should rest on the tops of the air bag posts.
7. Ensure you will have enough room to mount the mini air tank that will be disguised as a frame rail. Your air bladders will sit behind this mini air tank.
8. Make your air tank. Since the air tank will be in front of the bladders, mock up your bladders again and mark where the tank will connect to the frame. Cope the edges of the air tank so that it fits nice and tight between the frame rails.
9. Weld slugs inside the mini air tank. This will allow you to test for air leaks before you weld to frame.
slugs
slugs welded inside mini air tank
10. Drill two holes in the mini air tank to house the two 1/8” NPT bungs. One bung will house the Schrader valve and the other will house the air fittings. Remember that you will need to place the Schrader valve in a location that’s easy to access since you’ll be adding air now and again.
11. Weld in the 1/8” NPT bungs.
12. Assemble the entire system on a bench and test for air leaks. Screw T fitting into air tank. Connect the air fittings to the T fitting. Connect air tubing to air fittings and air bladders. Screw Schrader valve into air tank. Fill the tank with air (your air bladders should inflate) and stick the system in a bucket of water.
13. Tack your air tank to frame.
14. Add two side pieces to the bladder bracket. If you’re not sure about the exact height of the bracket, give yourself some extra metal.
15. Put the seat pan on the hinge and rest the seat pan on the tops of the air bladders. Ensure proper seat angle.
16. Tack bracket to frame.
17. Review seat hinge post placement (step #2).
18. Tack seat hinge post to frame.
19. Attach seat hinge to seat hinge post.
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