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…
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:
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)
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 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.
20. Place seat pan on seat hinge. Ensure the top posts on the air bladders touch the back of the seat pan.
21. Drill two holes in the seat pan
22. Weld two bolts to seat pan
23. Attach seat pan to seat hinge
24. Mock up placement of seat posts (the two posts that connect your seat pan to the air bladders)
25. Make two posts using the round bar.
26. Tack seat posts to seat pan
27. Attach air bladders to seat posts.
28. Sit on your beloved air suspension seat and ensure proper placement.
29. Weld everything up.
30. Get your seat pan covered. I went to best guy on the planet (Christian at Xian Leather) and he treated me right.
I just finished mine - I was going to use the compressor as I bought the complete kit but there was far too much to try and conceal so I dumped the compressor and have gone the manual pump route, which takes all of 2 secs to fill both bags and is far neater.
BTW good work - one question though, have you made a hinge so that when your bags are fully defalted the bags drop down inline as obviously the angle is increased/decreased when the bags are at the highest and then lowest point? If so how did you get around this?
very nice but too difficult for me !!! I only can bolt springs....I saw a custom bike with an air spring saddle suspension taken from a mountain bike (like a Fox air spring).
Very nice. Where did you score the HD Police bags and how did it set you back, if that's not too rude to ask. The set-up from custom chrome or somebody was like $1500 bucks and figured a guy could take all of this BT stuff and stuff into soft tail frame for that much.
i probably have a few bags left over. i'll check.
$179 for the bag on ebay.
same basic bag at mcmaster carr $42
$328 from the makers (justified defiance) of the most stinky helmet on earth
love the fox shock idea.....going to try it out on my next build for sure
Great write up. I am doing one on my current project with a single bag but it's big about 4" in diameter. I am running a compressor because I want it to go down when not in use. Does you system have a bleed down into the tank or is it up all the time? Here is a picture of mine now, not quite complete. Sorry it's the only current picture I have you can barely see the compressor behind the battery. I would like to get rid of it if I could figure how to have a closed system that I can empty the bags when parked.
Last edited by choppa; 02-24-2011 at 4:25 PM.