Bearing Crush

amanco · Post by **amanco** » Wed Oct 01, 2008 5:57 am

Bearing Crush
When journal bearings are assembled, each insert is installed either in a semi-circular bore (cam bearings) in the block (or rod), or a similar area of a bearing cap. When assembled into the cap and the bore section of the block, the ends of the inserts stick out slightly. When the cap is put in position, the ends of the bearing inserts butt up against one another before the cap actually seats against the block. In this position, the inside diameter of the bearing will be slightly greater when measured between the centers of the inserts than when measured between the two ends of either insert. The difference between these two diameters is the bearing crush. The crush is removed when the main cap bolts or connecting rod cap bolts are torqued.

OK, now for my question. Can rod/main caps be loosened and removed, existing bearing clearance checked and if OK caps replaced and re-torqued to spec? Or is the "Bearing Crush" a one time thing and new bearings must be installed once the caps have been removed.

tmbrwolf · Post by **tmbrwolf** » Wed Oct 01, 2008 6:15 am

Yes, if the bearings are within spec then they can be reused,

HingsingM37 · Post by **HingsingM37** » Wed Oct 01, 2008 6:21 am

If I am understanding this correctly, my answer would be yes you could re-torque. Otherwise you would need a new set of bearings everytime you took a plastic -guage measure of the bearings clearance to the journal or did an inspection? If I understand correctly you are suppossed to torque down and measure the clearance with your new bearings especially after the crank has been machined or polished? Thus you have to remove the caps to get your plasticgage out or check for unusual tightness? Thats how I have always done it. I could be wrong

Charles?

amanco · Post by **amanco** » Wed Oct 01, 2008 7:46 am

The plastiguage measurement is what I was just thinking of. It would be impossible to do if it were a one time thing. That is good. I am going to check tolerances on a 230 and call it good if it is good. Thanks for the brainstorming!

Post by **Cal_Gary** » Wed Oct 01, 2008 11:28 am

Remember the bearing clearance is critical: Too much = little or no oil pressure and you can spin a bearing; too little and you'll end up with a grinder that will score up everything. If you are that deep into it, replacements seem to be a good investment, but I know, a $ ain't what it used to be....
Gary