Assuming that the strut is not blown out, how does someone go about discharging one of these without personal injury?
30.30 at 20 yards? I think that will ruin the tube...
And a second question. Are modern "throw away" struts housings threaded at the top retainer? Or are they some sort of crimped fit...? The car in question is an A2 Golf GTi that I would like to build "home-made" coil overs for. I have the Bilstein inserts, and I have a set of yard sale #400 springs and retainers. Just need to know what I am looking for at the wrecking yard so I can convert the tubes.
Uh...I'm pretty sure you just remove the glad nut, slide out the old strut, chop the tube down (part of the car not part of the strut) and reweld the threaded bit back on or cut less and have a shop thread the tops again. Cut reweld works best for most.
Edit: lol did you really call a mk1 golf "modern"? Aren't all of them considered antique by now?
The way I have done it is to cut the strut shaft off very short, then push the stub into the strut. While it is inverted in a bucket, swaddled in rags to prevent backsplash.
I suppose you could also just grind a big notch in the shaft and push it through. Strut shafts make awesome tools though, you can make punches and alignment dowels and other stuff, so I like my method.
Most non servicable struts are crimped or welded, so you're cutting the top off.
Installing sleeves on rabbit strut tubes is pretty well laid out.
I am not sure what you are asking. Rabbits have either internal or external threads on the top of the strut tube. To make coil overs you want the external thread type.
As far as the cars in the junkyard thing keep an eye out for cabriolets. I have never seen them with internal threads.
And the releasing the gas charge thing has me totally stumped. I can't understand why this would ever be needed
Are your Bilsteins new? HD or sports?
Billy's come with both sets of retaining nuts when new. The large shaft diameter will not work with the VW nuts. If your struts are used and you either got only one type or none you are kinda boned. The Bilstein nut also has the shaft seal integrated so it's pretty important.
If you have random Bilsteins off of a whatever car I wish you luck in your conversion. Rabbit strut inserts are the shortest out there and anything else will either lift the car or dramatically reduce wheel travel.
A torch 
I used celica struts on my SE-R for the inserts. I just walked through the junk yard with a caliper until I found ones that were the appropriate diameter.
As someone who considers an A1 GTI modern, and who has changed the strut inserts on the car (using gas shock cartridges), just thread the cap off. With the spring off, the strut cartridge will be nearly fully extended. Your biggest challenge will be getting the rusty cap to come off. Lots of penetrating oil, heat and a big mother pipe wrench.
Opps.. I buffed that up. Sorry for the bad info. The car is an A2, not an A1. And I did not mean to refer to the car as modern. What I should have said was if I found a set of modern replacement struts (ie, Monroe or whatever found in the boneyard) would these have threaded tubes? I see could be either way. Just have to look. And thanks Knurled, looks like you have the answer for discharging the pressure from what would be the donor strut. And that is what happens when I am trying to work, at work and trying to do something important at GRM... I mess up both.
They all came from the factory with threaded tubes that accept inserts. There were some aftermarket struts that replaced the whole unit but those were uncommon here outside of the salt belt.
There is no need to discharge the gas pressure. That is contained in the insert. Unless you plan on drilling into the insert to replace the oil or revalve them or something.
For what it's worth, I've never played with transverse VW strut tubes, but I did install Konis in Subaru housings, which require cutting the tops off and drilling holes in the bottom for the retainer plate.
And since I was putting the Subaru struts in a Mazds, I needed to hack up FOUR struts to make two.
I think the instructions for the inserts that go in the disposable tubes (retained with a bolt in the bottom) just tell you to drill a small hole in the bottom end (pilot for that bolt) and expect a mess.
Yeah, that is great if you only have a drill and don't mind standing over a geyser of one of the most foul smelling automotive fluids available. (Ford Limited Slip Additive is and will always be #1)
My method does require a cutoff disk but it puts you well away from the splatter zone.
