I am putting together my engine and the end play isn’t in spec yet( don’t have the numbers off the top of my hand as I’m not in town while writing this). To my understanding,I take both thrust bearings and clamp together under soft pressure and sand them on a piece of 600 grit with light oil like lubricants (like wd40) in a figure 8 motion on a piece of glass or like granite till I hit the desired spec. Am I missing anything ? I was told that only 1 side should be sanded and that it should be the side of the bearing that is facing the crank snout .

 

I don’t clamp the halves together when doing this, because I’d be afraid to damage them. I sand one half at a time. Mic the width before you start sanding on each half. At initial mockup, let’s say you find you need another 3 thou…sand each side 1.5 thou, on each bearing half. Clean the halves and set it back up to double check. It doesn’t hurt to sand the side facing the rear as long as you leave the oiling channels. If you need to remove so much material that the channels are drastically reduced, then you can re-cut the channels with a file. I wouldn’t feel comfortable sanding a lot of material off of just the front, because your making that thrust surface awfully thin.
As you stated, use a piece of granite or thick glass. Apply a little cutting oil, wd-40, or whatever thin oil you have, to the surface. Lay down the sand paper on the oiled surface…this holds the paper in place. Put a liberal amount of oil on the sandpaper and with light, even pressure, go in figure 8’s. Pretty much as you described above. Go slow and measure often, in 3 places across the bearing shoulders.

 

One thing to remember is that the crank is only ever pushed forward so the back of the thrust bearing is the only side that will be worn. If you have a clutch it pushes the crank forward, and so does a torque converter. If you can do this sanding operation such that the back side of the bearing is intact that may be a good idea.

 

You are correct from a loading standpoint. The crank walks front to rear, under rpm. Front accessory drives and belt driven superchargers can push the crank rearward at rpm, but the majority of the load seen by the thrust bearing is from converters and hydraulic clutches.

 

I really like seeing chevelles reply’s. Very educational