19-05-2018, 08:24 AM
(This post was last modified: 19-05-2018, 08:24 AM by Dave Wortley.)
Erich,
Standard,non-sports A7 had gudgeon pins with a half moon slot in them. Through this passed a high tensile 1/4”BSF high tensile hex head screw, there being a clearance hole for the screw at one side of the split little end in the conrod and a tapping in the othe side. Hence the gudgeon pin was clamped in the little end. It is a weak design, because the gudgeon pin clamping is inadequate, allowing fretting between the pin and the screw. Bad cases can actually be complete removal of a half moon shape in the screw by the harder pin material.Even if it doesn’t get as extreme as that, any wear in the little end hole allows the gudgeon pin to float endwise,creating deep grooves in the cylinder bore. Sports A7 had a bushed little end, end float of the gudgeon pin being controlled by internal circlips in the piston.
Cheers,
Dave.
Standard,non-sports A7 had gudgeon pins with a half moon slot in them. Through this passed a high tensile 1/4”BSF high tensile hex head screw, there being a clearance hole for the screw at one side of the split little end in the conrod and a tapping in the othe side. Hence the gudgeon pin was clamped in the little end. It is a weak design, because the gudgeon pin clamping is inadequate, allowing fretting between the pin and the screw. Bad cases can actually be complete removal of a half moon shape in the screw by the harder pin material.Even if it doesn’t get as extreme as that, any wear in the little end hole allows the gudgeon pin to float endwise,creating deep grooves in the cylinder bore. Sports A7 had a bushed little end, end float of the gudgeon pin being controlled by internal circlips in the piston.
Cheers,
Dave.