Upper rod bearing (wrist pin bearing)

[HeadSmess]

never had an issue with either rod bearings, crank bearings, blah blah... until small things like the ring locating pins decide to let go...

my funniest top end bearing failure was on a honda ct90, overbored to the 110 piston...

someone stuffed up when they set the reamer for the lil (bronze) bush they decided to use rather than the needle bearing(the gudgeon pin being 1mm bigger was the reason it got bushed instead)...

anyways, lasted all of 10km before it let go...where did the gudgeon pin go? no idea! made a mess of the piston, the rod...but that gudgeon pin had been vaporised! probably in the same place all them odd socks go for vacation...


meh, take the thing to a bearing shop, demand skf or nashi or something...

 

[sbest]

Sort of solving a problem I don't have, my pin is holding up well, I have been checking it along the way. No blueing or brinelling or other wear signs on the pin or rollers.

I am interested in the bronze bushing idea. Only seen it in 2 strokes on my 30+ year old outboards that called for heavy oil mixes. Many RC engines don't even have bushings but again heavy use of a very good oil. Any caveats when using a bushing? Any special needs, like an oil carrying helix or slot or holes in the piston?

Steve

 

[butre]

I use one of these http://www.bronzebushings.com/am-1014-14-sae-841-sleeve-10-mm-id-x-14-mm-od-x-14-mm-oal.html

I don't bother with helixes or grooves, just once you press it into the rod drill a hole for the oil to go through that matches the existing hole in the rod. there'll be about a 15-20 tenths clearance that the oil will happily fill. the main reason I use a bushing is so I can get away with a titanium wrist pin and so when it does inevitably fail it doesn't ruin my expensive head and the jug I spent hours porting to perfection.

I actually started using a titanium wrist pin long after the bronze bushing, previous experiments with titanium wrist pins and needle bearings had failed so I was put off from titanium for a while

by the way, that "SAE 841" is oilite, which is an oil impregnated sintered bronze material that runs very happily with tight clearances. just don't try to cut it unless you have a lathe and very sharp carbide tools, or else you'll just smear the metal over the pores and ruin the bearing. don't try to ream or grind it either.