Tuesday, November 21, 2006

VW - Case Savers


Case savers are threaded steel inserts installed in the VW crankcase to prevent the head studs from shearing their threads and pulling out. American rebuilders of VW engines have been using them since the late 1950's. Volkswagen began installing them in their cases in 1973.

I have seen four different types of case savers intended for after-market installation. The ones I use are threaded 14 x 1.75 (exterior), thru-threaded on the interior for either 8mm or 10mm studs. Variations include those which are closed at the bottom and those having different exterior threads but 14mm x 1.75 seems to be the most common. (The earliest ones I used had an SAE exterior thread.)

Case savers are installed as a matter of course by most overhaul shops. If building a large displacement engine using an early crankcase you will want to select a case saver that will not interfere with opening the spigot bores for larger cylinders, nor get in the way of relieving the case for stroker cranks.

Installation is a straight forward drilling & tapping job. Special tooling is used to support the left case half (i.e., the one with the main bearing studs). Tapping is done with a Tap-matic sensitive feed or by hand. The case-savers are normally installed with high strength, hi-temp loc-tite and allowed to cure before any crank relief work or machining the spigot bores. To thread the case savers into the case I modified a couple of old spark plugs, fitting them with 8mm and 10mm stud-ends to serve as installation tools. (If no one is watching, I run them in with an air tool.)

When properly done, installation of case savers is a one-time job that eliminates the possibility of pulled studs. Since case savers are nothing more than threaded sleeves, anyone with a lathe can make them. Although seldom advertised, case savers are available from VW after-market suppliers such as Johnny’s Speed & Chrome, Barrett Enterprises, or Hoy-Fox. Cost is about forty cents each; you’ll need sixteen.

Case savers, often listed as ‘stud inserts,’ are superior to Heli-coils due to their larger contact area and are used in aircraft engines where maximum strength is needed.

No comments: