The pilot of the ski-equipped aircraft had taken off from an abandoned strip that was in a deteriorating condition with rocks scattered along the landing area. After arriving at his destination, he landed on a well-graded runway with packed snow that was suitable for either wheel or ski operation. After touchdown, the aircraft began to veer to the left. Subsequently, it went off the left side of the runway and the left wing of the aircraft hit the left wing of a Piper PA-12, N3140M. After that, the aircraft continued until it struck a snowbank, then traveled about 50 feet further before coming to rest. An exam of the gear revealed that the left ski was worn. The overlayer was scraped away and approximately an 18-inch, outboard portion was bent inward. There was evidence that the ski had hit the snowbank while the left wing was low causing a transverse fracture and failure of the left axle (a non-standard C-185 axle). Improper bolts had been used to install the non-standard axles and no shims had been used to provide proper axle alignment.