Working on my GB1 pack, about to mount the bumper, and I can’t find any info about the spacer between the back of the bumper and the front of the cyclotron (in photo below)
From the posts, I have read it’s about 1/8" to 1/4", and I assume aluminum.
Also looking for info on the screw that goes into through the bellows and into the cyclotron. The screw list has 10-32 socket cap screws for the sides of the bumpers, is it just a longer one of these through the bellows?
Unsure what is screen accurate but I used a 3/4-inch steel spacer for a 1/4-inch bolt. For my nick-a-tron resin Shock Mount, I removed the faux bolt head and drilled a hole through. A 4-inch long 1/4-20 stove bolt passes through the Shock Mount, Bumper and Cyclotron center, secured by a washer & locknut inside the shell. I also used a thick rubber washer between the Shock Mount and Bumper.
It kinda depends on what pack shell and bumper combination you’re using. The gap can vary anywhere from 1/8" to 3/4" depending on how things line up and how far back you mount the bumper. Most hardware stores carry aluminum standoffs.