Don Terrill’s Speed-Talk

I'm just curious, why .001" bearings are called "undersize"?

I understand they increase the running clearance by .001 having the I.D bigger in relation to a STD bearing, so, shouldn't they be called oversized?

CB663H1 is an undersize bearing. It doesn't add .001" it takes away .001". CB663HX adds clearance.

BrazilianZ28Camaro wrote:I'm just curious, why .001" bearings are called "undersize"?

I understand they increase the running clearance by .001 having the I.D bigger in relation to a STD bearing, so, shouldn't they be called oversized?

LIke robert1 posted, 1 bearings tighten the clearance .001
X bearings add .001

Ok, thanks but lets say If you have a set of .020" rod bearings and need .001" more clearance you should get .021" rod bearings called undersize?

lorax wrote:

BrazilianZ28Camaro wrote:I'm just curious, why .001" bearings are called "undersize"?

I understand they increase the running clearance by .001 having the I.D bigger in relation to a STD bearing, so, shouldn't they be called oversized?

LIke robert1 posted, 1 bearings tighten the clearance .001
X bearings add .001

I do believe these are from Clevite PNs?

Do you know how King bearings define their PN code in relation to size?

Say you have the #CR 807SI 020 and need .001 more clearance, do you get the CR 807HPN 021 or ??

I looked at the King web site but it was no help.
Thanks

BrazilianZ28Camaro wrote:Ok, thanks but lets say If you have a set of .020" rod bearings and need .001" more clearance you should get .021" rod bearings called undersize?

No, you would get .019 if you use a Clevite. If you use a King, then you get 20X

lorax wrote:

BrazilianZ28Camaro wrote:Ok, thanks but lets say If you have a set of .020" rod bearings and need .001" more clearance you should get .021" rod bearings called undersize?

No, you would get .019 if you use a Clevite. If you use a King, then you get 20X

thanks Lorax

That's what I thought=.019" undersized in relation to a STD bearing.

lorax wrote:

BrazilianZ28Camaro wrote:Ok, thanks but lets say If you have a set of .020" rod bearings and need .001" more clearance you should get .021" rod bearings called undersize?

No, you would get .019 if you use a Clevite. If you use a King, then you get 20X

Got it...

and the Sealed power PN for that size is the Z87100CH19...

You are more likely to find the +/- .001 bearings in Clevite or ACL. FM seems to be hard to get these days and always seem to be back ordered.
The others seem to have good stock when needed.
You can get a 009 .010 .011-.019 .020 .021 for under sized journals and a 1X for less clearance and a -.001 .002 in the HP series of bearings.

One thing to note...first I know your overseas so it it tough anyway.

Bearing QC is not very good and you can end up with a set of std and a set of .001
that only change the clearance from .0003 to .0012
so if you can check the clearance with what you have ..ball mic the bearing and
then who ever you order your bearing from see if they can ball mic the thickness
and do the math to make sure you get what you need.

OK

Thanks for the tips fellas.

Brian B wrote:One thing to note...first I know your overseas so it it tough anyway.

Bearing QC is not very good and you can end up with a set of std and a set of .001
that only change the clearance from .0003 to .0012
so if you can check the clearance with what you have ..ball mic the bearing and
then who ever you order your bearing from see if they can ball mic the thickness
and do the math to make sure you get what you need.

The problem with checking the bearing shell thickness is that this will not necessarily tell you what the verticle oil clearance will be when the bearing is installed. There may be variations in housing bore diameters and the various bearing manufacturers do have differing spec's for bearing crush. The only way to verify verticle oil clearance is to torque the bearings in place and measure with a good quality dial bore gauge.