big end bearings......

[johnyo]

Hey there,

I've just replaced the big end bearings in my Minor as there was a pretty ominous knocking. I was told by the shop that I bought the replacement bearings from that i needed standard size bearings as the numbers stamped on the bearings were 2783 on one side and 2A 690 on the other. After replacing them the knocking has got worse and so i think the crankshaft has been reground. Does anyone know if these are the numbers for standard bearings or if i need larger ones. Cheers very much,

john

[aupickup]

standard bearings are normally marked STD

any oversize bearings will be marked as 20 30 40 etc

[Alec]

Hello John,

I assume that you took the old shells to the shop, so I'm sure they would have identified them as being standard or undersize.

It does sound as though the crank is worn however and needs re-grinding and another set of undersized shells fitting.

Alec

[bmcecosse]

If you look at the back of the old shells they will indeed be marked with the oversize - to suit an undersize crank. Were the big end journals 'smooth and shiney' - or were they 'grooved and dull' ? Could well be the main bearings are badly worn - you can take the centre main out for inspection when the sump is dropped - and if worn then there is no hope - the crank needs regrinding.
One of the main reasons this happens is that sometime during the life of the car - the dished steel plate under the oil filter canister has been lost - and then the oil is not being filtered. Other reason of course is owners not topping up oil when required and/or never changing the oil! So - be sure to check that plate (and spring) are present under the oil filter when doing the crank regrind which seems necessary.