shuffle pinning
As an additional option during your engine rebuild, we can now offer a dowel-pinning service on your crankcase main bearing housings as added protection for engines put under strain, i.e. on track-days and in competition.
Often called 'shuffle-pinning', this precision operation is designed to stop irreparable damage from movement or 'fretting' of the crankcase between the main bearing journals web faces. This is most commonly found on early 911 magnesium alloy casings, (1968 onwards 911 engines under 3.0 litres) and hence these crankcases will benefit the most. It also helps resist crankcase main housing misalignment on magnesium cases which is a product of time and many heat cycles, as well as high stress. As stated in the highly regarded "Porsche 911 Performance Handbook" by Bruce Anderson he comments as follows:
"In racing applications where greater than 250 hp is anticipated, dowel-pinning (or shuffle-pinning) the magnesium crankcases cuts down on the case shuffling around the main bearings. This modification will extend the life of the crankcase and the crankshaft by reducing the flexing and moving. The modification consists of installing ten dowel pins, one on each side of the main bearing, to prevent the case from shuffling around the main bearing."
The pictures here on this page show the Autofarm dowel-pins fitted to a racing 3.3 Turbo Aluminium crankcase.
Therefore, a 'shuffle-pinning' upgrade will prolong the serviceability of your original crankcase and crankshaft, which will save you premature engine rebuilds on your road or racing Porsche. And for collectible 911s, being able to preserve the highly valuable and important original case and shaft ensures the car's value is not compromised unnecessarily nor that is loses its status as a genuine 'numbers match' 911.
