encapsulated crank bearing

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FGF
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encapsulated crank bearing

Post by FGF » Fri Aug 07, 2020 3:13 pm

Hello ,

re-building the crankshaft , i 've received from a serious supplier an encapsulated ball bearing (LJ7/8ZZ) to remove the 65-5883.

it's not a real sealed bearing , is it really a better design than the original one ?
i think it would be better to strip the conrod side cover to let the engine oil cross the balls freely ?

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Re: encapsulated crank bearing

Post by mlb50 » Sun Aug 09, 2020 3:19 am

If your motor is B50, none of the main bearings should have integrated seals. They need oil flow.
B50 @ 10:1 - what's a leg between friends?

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Re: encapsulated crank bearing

Post by FGF » Sun Aug 09, 2020 4:44 pm

Thanks mlb50,
yes it 's a B50SS and the supplier provide two NTN roller bearing Ok but a LJ7/8ZZ for the ball bearing .

i agree with that choice for the 6206 metric in the gearbox on the sleeve gear to limit leaks and ,
only one seal would be enough.

For the crankshaft it could be useful to limit the oil flow through the primary case but
not best for the ball bearing lubrication , and the ZZ is not a couple of seals but only two protections for dust .

i don't understand this supplier choice...
vilo.jpg

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Re: encapsulated crank bearing

Post by mlb50 » Mon Aug 10, 2020 3:53 am

For suppliers, often it only what is available now for modern machinery. Bearings types from 50 years ago may no longer be relevant so they can only offer what is the nearest equivalent. Fully sealed wheel bearings are a big improvement to the originals. I fit one side sealed bearing to the gearbox output.

For the primary, it is essential to have the drive side main bearing breath and feed oil through. Some B50 owners have a problem with excess oil into the primary, but I modified mine to be the same as A65 and T120 where there are 3 small holes (2.5mm diameter) drilled into the crankcase wall at the level of the bottom chain. This maintains a constant oil level for the primary. Never had any problem with this arrangement.
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