Madjak

Most older cranks were done the same way as the 6 above. Especially the straight fours with only 3 main bearings. The old mini cooper cranks are cross drilled through the bearing journals requiring no plugs.

For a performance crank you don't want the oiling holes in the bearings on the outer ends. I think it's to do with the centrifugal forces pushing the oil only to the outer side of the bearing and it has to work against the rotation force to get to the top and side of the bearing where the load is on the upstroke. Something like that...

Twibs415

iTrader: (8)

Madjak, have you thought about adding extra Oiling holes into the rod journals? i only do it when im removing plugs as a while im in there type of deal, it seems to help rod bearings last as there is oil directly on the power stoke.

Madjak

I can say it has never occurred to me. I've read about teardropping the journal holes in the direction of rotation to help the oil change direction. How much this would help though is questionable.




At what angle do you add the additional holes? Any photos?

curly

iTrader: (25)

It's called manufacturing.

Thank god they don't have any oiling problems...

Twibs415

iTrader: (8)

you almost cant see it in this picture but the cross drill is there

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Madjak

Did you get the oil journal welded then bored out for lightening? I'll do some research on perpendicular drilling the extra holes in the big ends... interesting idea!

Twibs415

iTrader: (8)

No, they get bored out then plugged up with tapered aluminum plugs and red loctite.. makes removal easy if need be.you can see the smashed in plug on the far journal in that last picture.

it takes forever to bore out the big ends like that and i cant wait to do my next crank....

sixshooter

iTrader: (12)

Madjak

???

I spoke to a machinist and he said he could use spark erroding machine to burn them out. He has a 4mm nozzle that would remove the bearings without much damage to the surrounding crank.

Apparently the entire crank gets put in a fluid bath and the nozzle sucks the fluid up through the center whilst the outer body arcs and melts whatever is infront of the nozzle. The molten metal gets extracted through the nozzle via the fluid.

sixshooter

iTrader: (12)

For cleaning the holes when you get to that point.