Engine is apart to replace bad driven plate. The replacement used driven plate I found has what appears to be a sandblasted surface and a little bit pitted where it would ride on the 4th main. Can I just polish the end a bit with fine sandpaper? Would the pits be a concern with a Babbit 4th main? Really dont want to go to a roller 4th because of all the problems I've heard.
Yes polish it well, use emery cloth.
Pat, the fourth main cap is a critical part of the drive train. You want the tail shaft to have a good fit in the babbitt. Many times this means replacing the the ball cap with a rebabbited cap, if you do this it is good to have the shaft machined to true up. most of the time they are worn at a taper. Once that is done you order the cap undersize and have it turned to fit, I shoot for one and a half thou. Make sure the machinist knows where to index the cap, a recent thread on this topic will tell you how. KB
Ball cap clearance should be .002-50, Min., or you will smear it.
Max. should be .003 thousandths.
Keith is right, it should be machined, and should be bolted to the break drum, when machining, as that is the only way they can be 100 percent true, as that is the position it will be run in.
Pat, Herm is right about machining the two components together to have the output shaft true. He forgot to mention that when assembling the trans you must mark the two pieces and make sure they go back together the same way. He's done so many it's part of the course to do this without thinking.
Hope this helps.
Allan from down under.