View Full Version : crank pin bearings
16th April 2006, 15:53
how many km should the crank pin bearings last?
My 91 sportster has 140,000 km and i need to replace them. is it OK?
does anyone here have any expirience with "S&S heavy duty connecting rods set". should those crank pin bearings last more then other products?
You got a very good forum.
thank you for your answers
16th April 2006, 16:22
Welcome to the forum!!!
If my calculator is right, you got 86K miles or so out of your rod bearings. That's not unusual. I've seen'em go longer and I've seen'em go a lot sooner.
I think a lot of the wear just has to do with the roundness of the big end. They tend to elongate. If you resize them, though, they tend to stay. So be sure to resize your big ends. Get the clearance right.
I recently rebuilt an S&S flywheel & rod assembly with 60K miles on it. The rods were not bad, in terms of the big end roundness. We resized them anyway, but compared to the factory stuff I've seen, they weren't bad at all. So yeah, you may be right, you may get more longevity out of them. But I think if you resize your big ends and get the clearance right, it'll last a long time.
Everyone's bearing rollers and crank pins are pretty much the same materials-wise. You can get 2 and 3 hole crank pins though from S&S and the like, but I've seen them wear as much as the single hole factory pin. Oversize pins and oversize rollers are both available. Make the measurements on the rod, estimate how much bigger pin you need once the rod is resized (+.001 or +.002) for standard rollers, buy the pin so you can do exact measurements, resize the rod or get it resized, and then if it came out too big you get oversize rollers. Rollers are dirt cheap, although the cages are pricey. Pins are expensive. So do things such that you can set your final clearance with different size rollers. Rollers are available in 2 tenths (.0002") increments.
Also watch the thrust washers. There are two styles, recessed and flat. Make sure the type you use matches the type of bearing cages you use. This is important, you would not believe how many people have ruined their lower ends because they didn't know this.
16th April 2006, 16:26
Welcome to the forum! Aaron comes through again!
18th April 2006, 12:25
Thank you for your detailed answer.
18th April 2006, 12:56
Welcome to the Forum Nitsan, Glad you're here. Enjoy the forum. :tour
Thank you Aaron, for answers to some questions I've had. :clap
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