Re: 250 Crank Pin Bearing
Posted: Wed Apr 04, 2018 8:03 pm
Hello Matt
You are correct about sleeving rods, there are issues and it will normally weaken the rod. The picture eldert posted was actually mine and I won't go into that particular issue again
That said sleeving can work if there is sufficient parent metal and sometimes it's needs must, rather than a first choice. I recently built a 175 crank with a sleeved 250 rod (which is thicker) and a 30/38/18 bearing. The thickness of the parent metal of finished rod was actually thicker than the original 175 rod, so hopefully strength will be fine.
That's interesting the Mach 1S has a bronze cage, is it original? Seems an unusual choice and I've not seen it's use as a rod bearing cage before. Is it machined and wasted away to a thin section rather than the thick alloy cage section.
Nigel
You are correct about sleeving rods, there are issues and it will normally weaken the rod. The picture eldert posted was actually mine and I won't go into that particular issue again
That said sleeving can work if there is sufficient parent metal and sometimes it's needs must, rather than a first choice. I recently built a 175 crank with a sleeved 250 rod (which is thicker) and a 30/38/18 bearing. The thickness of the parent metal of finished rod was actually thicker than the original 175 rod, so hopefully strength will be fine.
That's interesting the Mach 1S has a bronze cage, is it original? Seems an unusual choice and I've not seen it's use as a rod bearing cage before. Is it machined and wasted away to a thin section rather than the thick alloy cage section.
Nigel