So I looked into purchasing aftermarket air shocks, but they are more than I want to pay if I don't absolutely have to. I thought for a bit about how I might be able to use the stock shocks in an "air only" mode in order to get full compression since the springs prevent the shock towers from collapsing completely. After puzzling a bit on what I might do to modify the factory shocks, I think I have hit on an inexpensive solution. Turns out its actually not that hard.
After pulling the shocks apart
I reassembled the shocks minus the springs and spring pieces - this stuff:
That worked OK until I ramped the pressure up to 100 PSI, when this happened:
This happened because the top of the shock and the upper tube are press fit and not screwed together. Normally the springs hold the shock top tight to the upper canister to keep them from separating. Without the springs, I had to find a way to hold the top of the shock secure to the upper canister.
After thinking on it a bit, here's what I came up with:
I welded a 1/2" fender washer to a nut and threaded it onto the shock. I was then able to thread the shock top onto the shock (washer inside the upper canister) until it was snug against the washer. The washer is wide enough to contact the top of the upper canister so the top is now secure and won't come loose. After test fitting, I pulled it back apart and made a couple of cuts in the washers with a cut off wheel to open up a passage for air to flow into the shock (the small hole on the shock top is where the air comes in). The cuts also make a handy spot to slide a large flat tip screwdriver blade into in order to move the washer around or to hold the nut/washer still when I need to unscrew the shock top next time.
Then I put it all back together
and stuck it on the bike.
But would it hold air?
So far the answer is yes.
I've had it up to 160 PSI for a few hours now with no air loss so I think I am good. Obviously I can't ride the bike to test it further, but I have bounced the bike hard quite a bit and it seems solid. I won't know for sure until I ride it though which is still a long time away.
At 160 PSI there is about 5 1/2" clearance between the rear rail and the tire - full extension.
When I let the air out (70-80 PSI seems to be the deflection point) I have about 1 3/4" clearance.
This is probably low enough for my purposes, I don't think I want the frame (or eventual fender) to actually make contact with the wheel in case the shock decides to let its air out on the road somewhere.
Also, while there are no springs in the shock, there IS oil. ATF to be exact. This is one of the nastiest (30 year old shock oil, anyone?), messiest jobs I've done lately. Having to blow out the seal with compressed air while the shock is full of oil is a nightmare.
Anyway, at this point that wraps up what I wanted to get done on the back of the bike for now. I'll figure out where to locate the air compressor and so on when I actually get to the build part of the project.
On to the front...
A few of my favorite things...
82 GL1100 Interstate - Current Project
99 Vakyrie Interstate - Daily (when the weather is nice) Driver
78 GL1000 Vetter - Restored to original - Sold
79 GL1000 Vetter - Refurbished as a Driver - Sold
78 GL1000 Naked - Project I never got around to - Sold
78 GL1000 "Old Gold" - The one that started me on this crazy path- Sold
95 20th Anniversary 1500 Wing - Sold
99 Kawi Drifter "Faux Indian" - Sold
03 100th Anniversary Harley Heritage Springer Softail - Sold