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On Wed, 2003-06-18 at 10:36, Jim Adney wrote: > On 18 Jun 2003 at 1:15, Shad Laws wrote: > > > > VW specified *approximately* the SAME preload for both kinds of head studs! > > Agreed, but I wouldn't be surprised if they allowed for a slightly higher > preload with the 8mm studs, given that they put them in 1/2" steel inserts. > > The increase from 16.4 to 18is about a 10% increase, while the increase from > 10mm to 12.4mm is a 24% increase, so this sounds like a good engineering > decision. > > BTW, I was surprised a few years ago to find that type 4 head studs are step > studs, with 10mm (is that right?) threads into the case, thin shanks, and 8mm > threads at the head. This seems odd, since these would then seem just as > likely to pull out of the case as our 10mm studs (assuming the same preload.) I > suppose VW decided that step studs were cheaper than inserts, but this > surprises me. > > Perhaps I'm wrong about the case end diameter; if they are 12mm there that > makes a big difference. Do the type 4 head nuts get the same 18ft lbs of > torque? Or it may just be the stronger case alloy that makes all the > difference. What do you think? > The Factory inserts for the 10mm studs were .5566-.5585 dia. Part number ZVP 107 101. Have 2 sets of them here in front of me. They were made by an American company "Keenserts" manufactured by: Tridair Industries, Torrence CA. -- Russ Wolfe '66 FB MT '71 FB AT '65 Bug (not running) russw@classicvw.org http://www.classicvw.org ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ List info at http://www.vwtype3.org/list | mailto:gregm@vwtype3.org