Re: Re: Re: Re: Re: Shimming Rod Bearing?

Subject: Re: Re: Re: Re: Re: Re: Shimming Rod Bearing?

Comments:
: Tyler, : If you take it apart again "plastigage" the clearance to see how loose it is. : If the knock goes away when you depress the clutch, you may have excessive end play with the crankshaft. Usually, the center main bearing has the wear surfaces on the cheeks to restrain fore/aft movement of the crankshaft. Push the crankshaft all the way forward or rearward and place a feeler gauge between the crankshaft and side of the bearing and compare the results with the specification. Excessive endplay may knock. : While you're at it, measure the play on the rods. I had a race engine one time that had lots of side clearance on the rods. They would slide back and forth and rattle. It sounded bad, but I drove it several years that way. : Ken McWilliams : Dayton, Ohio : : : : Tyler, : : Its a early MF Pony N62A Its not so-much a knock but a thwuck slap type sound. I miced the crank it was in round, just the number 1 rod journal was .001 smaller then the others. I had to make a cluch clip for one of the fingers. When I pushed the cluch in it lessend maybe its that flappen in there. But to be on the safe side : : I'm going to drop the pan again and retork all the cap bolt. By the way the old bearing where made of covered brass! : : : If it's a removable bearing, then, it's not babbit, but it's known as an inserted bearing. As I wrote before, the coating on the bearing is thin and is back-up with steel. If you shim the bearing, you may very well go beyond the wearable coating and cause the steel backing to rub the crankshaft journal. : : : I wouldn't stop searching for a bearing until all sources are exhausted. : : : Post again giving the engine brand and model. Someone may have a source for this engine or even an interchangeable part from another engine that will fit it. : : : If you have a knock, use a micrometer and measure the journal diameter in several places. Chances are that if its knocking, then, it knocked before tearing down and the journal is no longer concentric. BE CAREFUL. You can create more damage with a tight bearing riding on an out of round journal. : : : Good luck! : : : Ken McWilliams : : : Dayton, OHio : : : : : : : : Tyler, : : : : : In the old days the rod bearings were babbit. The babbit material was cast into the rod and could be recast when reconditioning. The bearing inserts used in rods and main bearings today are very precision to assure proper oil flow and dimensional control. The insert bearings are laminated with a soft material on the surface to act as a sacrificial material which will wear before the crankshaft or camshaft. If you shim a worn bearing, you may expose the harder layers of the laminate which will ruin the bearing journals. : : : : : The replaceable bearings are too cheap to risk ruining a good bearing journal on a crankshaft. I would not recommend that you attempt to file the bearing caps. It was good for model T's with babitted bearings in the depression, but not for today's engines. Don't do it. : : : : : Ken McWilliams : : : : : Dayton, Ohio : : : : : : I read somewhere that you can snug up a loose bearing, by filing the opposite : : : : : : sides of the bearing and putting shim stock of the right thickness behind the bearing. : : : : : : Has anyone heard or done this? : : : : This is a old style motor that has the babbited bearing. The trouble is that under sized bearing are not avalable for this motor. and only one journal is under sized. I replace the bearing and there is a slite knock. that I would like to remove. Would shimming help this. I also would not file the bearing cap only the bearing itself. : : : : To shorten its radius and give room for the shim stock under it. I also would drill the oil hole in the shim stock to maych the bearing.

Optional Link URL:

Link Title:

Optional Image URL: