BEARING GRADES

[Guest]

Folks,

Can anyone explain what the grading is on bearings for main or big end, please.

For example STD B GRADE +10

I know the figure is the oversize but what does the single letter and or the STD mean...………………… other than a medical issue !! 

Many thanks in advance.

Richard.

[Anglefire]

I think they are just standard bearings +10thou 

 

 

[Clive]

If it were an OE bearing from the factory, it could be be a sizing thingy, they did it with pistons IIRC. But a plus 10? that would be a reground crank......what make of bearing? and is it a Triumph or Rootes one? (If Rootes Pete may have a better insight)

[Guest]

Thanks Mark & Clive,

It was just out of interest really as I have noted the letters before, but did not know the significance of such.

Many thanks.

Richard.

[Nick Jones]

AFAIK only pistons were size graded at the factory.

Nick

[JumpingFrog]

To elaborate on Mark's reply, standard here refers to the material the bearings are made from. This is specific to County/King bearings, STD will be a bi-metal aluminium material which isn't the greatest. The other material is sold as "heavy-duty" "tri-metal" or "lead-copper" I think these are marked CP or something along those lines. This is closer to the original VP2 bearings Triumph fitted at the factory...

The King website is quite informative with regards to their materials:

• Bi-metal bearings: http://www.kingbearings.com/material-type/aluminium-based/ (I think K-783 is the STD material).
• Tri-metal bearings: http://www.kingbearings.com/material-type/copper-based/ (I think K-794 is the CP material).

Point of interest: When you take an old engine apart, you can see when a VP2 bearing is knackered as all the babbit material gets worn away leaving just copper:

[Peter Truman]

interesting info. but that's a really bashed up old vice & still doing service! David it must be your grandfather's, grandfathers! 

Peter T

 

[Guppy916]

Pete old vice's never wear out, Like us they look better with age