Cutting slot in shocks for coilover threaded tube???

Are these slots cast into the shock body by Bilstein, or are shops performing this modification on a lathe? If so, I'm looking for a machine shop that will do this.

Sir if you are looking at the threads for adj. of the spring,that housing is made for that and a non C O  tube is of Thinner material. Speedway has A coil over that can be Adapted and used with most standerd shocks

if I had to guess, perhaps Peaches is wondering if an additional slot between the two "as delivered" ones could be added to the shock in the picture?

if you did it with a lathe... I'd expect you'd have to disassemble the shock so you only had the outer housing... and you'd probably have to fab up the fixtures to attach it into the lathe.

I'd think it be much more prudent to weld a tab to a shock body and place something like Ground Control sleeves around the shock body.

I can't imagine machining down a structural component and being ok with it. 

z31maniac said:

I'd think it be much more prudent to weld a tab to a shock body and place something like Ground Control sleeves around the shock body.

I can't imagine machining down a structural component and being ok with it. 

If you can disassemble the damper to just the tube, sure. And only if it's not a monotube. Other wise you're welding on a pressurized chamber which is a terrible idea. And if it's a monotube any distortion to the tube or weld material penetration to the inner surface is going to wreck the internals. On the other hand, IF (and that's a big IF) you know what you're doing cutting a groove into the body isn't that big of a deal. It's not the greatest thing for strength but in a shock with little to no bending loads (ie not a strut) it should be totally fine. I mean the pictured shock already has two grooves in it, konis usually have two or three grooves in pretty close proximity and never have any issues to my knowledge. I've definitely seen at least one person successfully add a new groove to a set of miata dampers.

While I wouldn't machine "threads" in a shock body I know that many Bilstein shocks do have "grooves" machined into their bodies. So the answer is yes and no.

 If the shock already has a groove machined into it from the factory  adding one or more additional ones to make it adjustable for ride height seems reasonable.  Bilstein sells many model of shocks with multiple groove for just this purpose.

dps214 said:

z31maniac said:

I'd think it be much more prudent to weld a tab to a shock body and place something like Ground Control sleeves around the shock body.

I can't imagine machining down a structural component and being ok with it. 

If you can disassemble the damper to just the tube, sure. And only if it's not a monotube. Other wise you're welding on a pressurized chamber which is a terrible idea. And if it's a monotube any distortion to the tube or weld material penetration to the inner surface is going to wreck the internals. On the other hand, IF (and that's a big IF) you know what you're doing cutting a groove into the body isn't that big of a deal. It's not the greatest thing for strength but in a shock with little to no bending loads (ie not a strut) it should be totally fine. I mean the pictured shock already has two grooves in it, konis usually have two or three grooves in pretty close proximity and never have any issues to my knowledge. I've definitely seen at least one person successfully add a new groove to a set of miata dampers.

I was just throwing it out there. 

I'm the guy that just buys the proper parts designed with the features I need vs trying to go super cheap and wing it. I've owned 3 different cars with Ground Controls and 1 car with XIDAs. I don't like to cheap out on stuff that can compromise my safety.

The groove is machined in on those and the shock tube is startlingly thick in that area.

I have cut that groove on an old set of Bilstien race shocks which were equally thick

But these shock bodies were not thin tube like other shocks. They weighed 5 lbs more than the konis for the same application (Alfa 105)

My Koni 30 series monotubes use the same method of supporting the perch. If you can't find/trust a machine shop locally Bilstein themselves list the service for $10 if I remember correctly. I believe Truechoice does it for about the same for Konis.