Cutting Automotive Shock Pistons?

So, not to bore with the details of why, but I need to take the guts out of
a set of struts from a car. The struts have a minimal amount of cylinder
that extend above the spring perch, but that's where I need to cut the top
of the strut off and remove the original shock "guts." One method I've
seen used is one of those pipe cutters that you turn by hand. That may
work, but it's pretty tedious.
My thought was to use my small Jet metal cutting bandsaw (assuming I can
get the thing clamped in there somewhat straight with the spring perch in
the way. But that would mean I'm not only cutting through the strut body
(which is mild steel), but I'm going to be cutting through the shock piston
along the way. Anyone know if shock pistons are hardened or some hard
alloy or something? I know they're coated (obviously), but is the thing
something that might eat my bandsaw blade?
Oh, and the strut will be depressurized first by piercing it with a hole in
the bottom of the body. Most of the oil will drain, but there may still be
some in there. I could also torch cut it and then clean up the cut, I
suppose, but I fear doing that with all that oil that could still be in
there.
--Donnie
Reply to
Donnie Barnes
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The pistons will eat a bandsaw blade. Sounds like an abrasive cutoff saw is the quickest.
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D> So, not to bore with the details of why, but I need to take the guts out of
Reply to
RoyJ
I used my 10" lathe for a couple last week. I just chucked up the body kind litely and hit it with a threading cutter (because that's what was in the toolpost). cut it right open, sprayed oil in a nice 360 pattern. 2nd one I stopped as soon as it broke through, turned the opening down into the chip pan. Then completed taking it off.
All is soft stuff except for the shaft itself. Bandsaw won't have any problem with anything except the hardened shaft surface.
It's messy, but I've cut them with a chopsaw, sparks and all, and nothing caught fire. My purpose is usually to salvage the shafts, so I don't mind trashing the rest of it.
Reply to
Rex B
How do you figure? I've cut a lot of shocks over the years. The pistons are made of cast aluminum, stamped mild steel, or powdered metal. There are shim springs in them that are hard, but the chances of hitting those is slim.
Reply to
Rex B
All I have is a mini-lathe. Unfortunately, these aren't mini-shocks. :)
I don't like the "except" above. I assume you mean it will just slow it down somewhat.
Hmm, didn't think of doing that. I've got one of those, and it isn't a mini-chopsaw, so I should be fine. Probably faster than waiting on that bandsaw, too.
Just out of curiosity, what do you salvage the shafts for?
--Donnie
Reply to
Donnie Barnes
Oops, I meant the shaft. The pistons are soft. The shell is just mild steel.
Rex B wrote:
Reply to
RoyJ
It is just the surface of the shaft that is hard. Chrome plated. Once you get below the plating it is easy to cut. Dan
Rex B wrote:
Reply to
dcaster
The shaft is hard-chromed. I doubt a bandsaw will be able to bite into it. The hard part stops about an inch from the treaded part, typically. It's obvious by looking at it.
Absolutely. I try to cut them close to the base, as the inner cylinder is some nice tubing that is useful. I try to miss it.
They make great arbors. Both ends are threaded on a reduced shank. The shaft is very accurate If you need to mount a gear, just turn the shaft to the ID, slip the gear on, then use spacers and nut to hold it. After a couple uses the shafting becomes stock for miscellaneous projects. I've seen shock rods used as replacement shafts for a QC box. They are often just the right OD, and all they need is a keyway. Very nice low-friction shafts.
Reply to
Rex B
Nope, the strut rods are hardened chrome, and no cutting tool will cut that surface. The inside is also darn hard, but can be cut with difficulty by carbide cutters. The chromed surface, however, can only be cut by grinding wheels or abrasive saw blades. The inside of the shaft is still too hard to bandsaw with any blade I have.
Jon
Reply to
Jon Elson
: It is just the surface of the shaft that is hard. Chrome plated. Once : you get below the plating it is easy to cut. : Dan
: Rex B wrote:
: > All is soft stuff except for the shaft itself. Bandsaw won't have any : > problem with anything except the hardened shaft surface. : >
Reply to
Philippe Gravelle
I haven't had any problem turning these once past the 'crust'. Doesn't turn very pretty, but it's machinable for my purposes. I don't think my HF bandsaw would have a problem cutting a de-chromed section. but I may have to try it now.
Reply to
Rex B
On 9 Nov 2005 14:28:33 GMT, with neither quill nor qualm, Donnie Barnes quickly quoth:
I've salvaged several strut rod shafts by cutting the housing open with a 4x1/16" cutoff blade in a die grinder. HF sells the disks in 10-packs for $5 on sale quite often.
Since they were old and worn out, they were already depressurized.
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Reply to
Larry Jaques
Thanks. Looks like I'll be using the chop saw or a cutoff wheel.
Yeah, and that's obvious when that's the case. Mine aren't depressurized, but I'm cannibalizing them nonetheless.
In case anyone cares, it's common to do this on strut cars to replace the shocks with single adjustable race shocks. It's easier for them to manufacture an "insert" that goes in the original strut body than to manufacture complete replacment struts.
So you drill a small hole in the bottom of the strut to depressurize, then cut the top of the strut off and remove guts. Then drill a larger hole in the bottom, insert the new shock, and run bolt through bottom hole into new shock to hold it in place.
--Donnie
Reply to
Donnie Barnes
Err, while you might normally be on to something, you might note that Miatas are double wishbone cars and my original (and subsequent) posts have been about cutting *struts*, not shocks.
Besides, the Spec Miata shocks are Bilsteins that you can take apart without cutting. :-)
--Donnie
Reply to
Donnie Barnes
Only if you are willing to lose a blade. I can't vouch for ALL strut rods, but the one pair I have are pretty darn hard stuff, and it ate my bandsaw blade in one second. I had ground below the chrome first. I had to do all work by grinding or turning with carbide tools, and it was quite hard on the carbide, too. I made an extension punch for an air chisel, and use it as a "mini jackhammer" for blasting holes through concrete walls. It does an amazing job without any attempt to harden it, even. I do have to resharpen the point on the thing a dozen times while making the hole, though.
Jon
Reply to
Jon Elson
Gee, and to think I didn't think I'd have any use for those shafts when done. :-)
--Donnie
Reply to
Donnie Barnes

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