Tools & Fabrication - Tapered 3/8" Extension?

My roommate had an awesome Craftsman 3/8" extension that was PERFECT for installing spark plugs on a header car. It was narrower in the middle, flared out to a full 3/8" end for the socket and flared out to a full 3/8" attachment for the wrench. I've searched for "flared" 3/8 extension, bone 3/8 extension, tapered 3/8 extension, etc with no luck. This leads me to believe there is a special name for it, and my roommate doesn't know what it is.

So, does anyone know what it's called and where I can get one? I drew up a crude idea of what I'm talking about from memory, I'm surprised it's not more common with how easy it worked with my headers and spark plugs!

A Herbrand j27 is close to what I'm referring to, but the taper I'm talking about is just a bit more aggressive than this... wobble extensions are starting to look like my only option :(

get a cheapo extension put it in a lathe and turn the spots down you needed tapered. if its just for spark plugs the material you turn down wont really matter too much, plus if its a cheapo and you break it your only out like 4 bucks and some time.

Lathe may be you best option, looked on snap ons site and they don't have anything.

or a grinder :) if ya dont got a lathe

Sounds like what I'll have to do... is steal it from my roommate next time I see him :gruffy:

Thanks for the input, guys!

FYI, there's something out there called a torque bar that is supposed to be manufactured to break after a certain torque is applied? Very close shape-wise to what I was referring to, and it would work for spark plugs since they should only be at 11ft-lbs...

I think what your reffering to is a torque stick for doing wheels they work like a torsion bar on an impact gun limiting the tq to the lug nuts.. Cant help you out on the extension i know older snap on extensions were pretty skinny in the center but the newer ones not so much... What about a 1/4 in extension with a 3/8 adaptor on the end?

I think what your reffering to is a torque stick for doing wheels they work like a torsion bar on an impact gun limiting the tq to the lug nuts.. Cant help you out on the extension i know older snap on extensions were pretty skinny in the center but the newer ones not so much... What about a 1/4 in extension with a 3/8 adaptor on the end?

Yes, a torque stick, thanks for the clarification! I like the idea of grinding down a cheapo 3/8" extension, I could even tailor it to specifically slip around the troublesome primaries I have. You know, I never thought of going with a 1/4" extension. Depending on the overall length of the head with a 3/8 adapter, that may be perfect. Also, with only 11ft-lbs for the spark plugs, a wobble extension may be the answer. I may not have found the extension, but sounds like I have a few more options to try, thanks for all the responses!