How to safely dismantle a gas shock absorber

**simonl** · 19th April 2012, 09:06 PM

Hi all,

I have some pics now.

As mentioned previously, I used a hacksaw to pierce the inner chamber that is under pressure. Due to curvature of a shock absorber, the hacksaw is able to pierce through with all but the smallest of holes if done with care.

Pic 1 shows the small nick required to equalise the pressure

A dozen strokes was all that was required before hearing a slight hiss of the gas escaping. Little oil escaped during this process due mainly by fact that the part that was cut was slightly elevated from the other end.

Once the hiss stopped, a few more stokes of the hacksaw to ensure it was indeed equalised was done.

The rest was done with a small angle grinder. Once the end was removed, it revealed a nut and the end of the shaft and the remainder of the oil, about 200ml of light machine oil. See pic 2

After the nut is removed, an assortment of parts are salvaged as seen in pic 3

The parts include a number of shim washers (as was mentioned by a previous poster) and the shaft

Once the shaft is removed, it needs to have the other end cut off by suitable means. I once again used an angle grinder as a hacksaw didn't want to know about it. See pic 4 After this its a matter of a tidying up the end on a linisher or other method.

Although these rods are indeed precision ground, they do not have as tight tolerances as I previously suggested. My metric 0.01mm micrometer measured 12.98 at one end and somewhere between 12.97 and 12.98 at the other end, some 180mm apart. So approximately parallel to within 0.008 or so, allowing for uncertainty in the mic and perhaps my technique. Still, a handy piece of kit that cost me nix!

The remaining shockers were held in a vice and cut with the hacksaw once I realised little oil spurted out. I still cut them outside with the angle grinder though.

The above process would be quite elementary to all but a few on this forum but hopefully it will provide some value to some..

Cheers,

Simon

**Steamwhisperer** · 19th April 2012, 10:25 PM

Thanks Simon

**Jekyll and Hyde** · 19th April 2012, 10:30 PM

Out of curiousity, did your shocks have any springs in them as well? The BA ford ones I hacked up had some decent springs inside....

**Bryan** · 19th April 2012, 11:09 PM

Simon, did you check for roundness at all? I have some chrome bar in larger sizes that I believe is often used for hydraulic rods. It varies in diameter enough at any given location to be fairly useless for precision gauging. The smaller sizes may be better, but I wouldn't take it for granted.

**Blu_Rock** · 19th April 2012, 11:14 PM

Thanks for the post. I've been meaning to hack into some shocks and now I know what to expect.

**simonl** · 19th April 2012, 11:48 PM

Originally Posted by Bryan

Simon, did you check for roundness at all? I have some chrome bar in larger sizes that I believe is often used for hydraulic rods. It varies in diameter enough at any given location to be fairly useless for precision gauging. The smaller sizes may be better, but I wouldn't take it for granted.

No in fact I haven't even cleaned up the ends yet. I have just put them to one side. I'll have a look tomorrow and get back to you. If they are not reasonably round then it was all pretty much for nothing!

Hi Jekyll and Hyde, actually the front struts had stiff springs in them, about 65mm long. The pictures above where of the rear shocks. I didn't make mention of the front cause the process was daily similar.

Simon

**simonl** · 20th April 2012, 11:49 AM

Hi Bryan,

Just checked for roundness, they are, can I say... Very round.

micrometer measure (sorry for imperial but it's my most accurate mic) 0.4910" both ways and at the other end it was 0.4909" both ways. So roundness is beyond the limits of my measuring ability and they are parallel to 0.0001" or 2.5 microns. Happy with that!

Cheers,

Simon

**Bryan** · 20th April 2012, 12:15 PM

Great, thanks. I'll look out for some shockies at the dump.

Dave J · 20th April 2012, 01:47 PM

Good to hear you got some pretty true round stock. I never take them apart, just cut the shaft off as close as I can get and throw away the rest. It saves the mess.

Dave

**grd** · 20th April 2012, 02:50 PM

Originally Posted by simonl

I was surprised at how low the gas pressure was.

They're dampers rather than springs, so the pressure (in most cases) doesn't need to be high.

I'd not thought of salvaging the rod before. It seems like they'd make a good source for the ways I'd need for a planned lathe build (note - "planned" so not likely this year) if they were a bit longer.

Graeme

**simonl** · 20th April 2012, 04:23 PM

I'm planning on some scraping projects, culminating in the scraping of the base of the tailstock, my compound slide (which was far from satisfactory from the get go) and possibly the ways of my mill. These rods may get used for parallel measurement of the dovetails. I'll see. Early days, I'm still studying machine tool reconditioning at this stage.

When I start I'll post a thread, I need to go shopping for some granite, straight edge etc first!

Cheers,

Simon

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