Fitting connecting rod shells

[vdubnut62]

I am probably wrong here, but it seems to me that Scotchbrite is too compressible and would remove some material from the whole bearing surface,
not just the tight spots? Especially when wrapped around a shaft.
Ron

[Crofter]

I agree with the scotchbrite not being very (at all) selective in removing material only where needed. I also think any form of abrasive is pure poison to an imbedable bearing. If you did use it you better plan on totally scraping a new surface that will remove all abrasive particles that otherwise there to rub the crank every time the oil film collapses (start ups)

The oil film has to be pulled between the two surfaces and if the contact is tight at the edges it wipes off instead of pulling in the oil film. The hardest oil film to disrupt is one where the two surfaces have virtuallly the same curvature; point to point contact is the least likely then to occur. Shimming to create an oblong hole does not make for a cushy nest for a round journal! Scrape those sides to get oil relief and attempt to get the top / bottom clearance down to .003" or less.

[Geno]

Geno, is this what your shim looks like? Did you do anything to your
   dipper (cap end) to index the threads for the best engagement of the insert?

They look a bit like that but I made mine from a beer can. They stop before hitting the crush area. I made sure my dipper went in as far as needed to prevent spinning the bearing.

When I put the shells in and found binding I tried to scrape the high spots. After a couple hours, (understanding the possibilities of Indian craftsmanship on the journal) I shimmed it up till it stopped binding.

I do believe the solid upper shell and hollow dipper make a big difference compared to splash only.

Thanks, Geno

[SHIPCHIEF]

My 25/2 had shimmed bearings from the 'factory'.
I have scrapped bearings. The tools were provided by some employee from the distant past. They consisted of old files that had been sharpened on the sides by grinding into scrapers. Make your own.
Use prussian blue to identify the high points, and these scrapers to carefully remove them, then reblue the shaft & refit & do again until you attain satisfaction.