Searched the threads and found lots of discussions about oil clearances, but not a firm opinion about the ball bearing type of cap.
Anyone use the ball bearing cap rather than the babbit original? I know it is a lot more expensive, but is it a better solution?
Just my opinion- waste of money. The original works fine. No advantage for the more expensive part.
I have had two engines with broken cranks and ball bearing fourth mains?? Some say the ball bearing fourth does not allow the trans to expand as it heats up so it pushes forward into the magneto and takes the rear main out? Just some thoughts for you.
I've run them for years and countless thousands of miles. Of course I build my own. The ones I make are locked to the output shaft but can slip in the housing. Historically I have made sure the shaft runs true prior to installing the bearing. Now I also utilize my "floating transmission shaft"
Here's the link to the past thread on Les's
"floating transmission shaft".
Here's another past thread on the floating transmission shaft.
I also have been running one for approx. 10 years. The sealed ball bearing can slip on the out put shaft. Prior to installing a ball bearing 4th main, I made sure the shaft runs true. I'm still running an early crank shaft.
I have a re-built short block with SCAT crank that will be replacing the current engine in my 13 touring.
The all important fourth bearing is not only there to align the rear of the transmission and to allow a lubricated enclosure in which the shaft turns, but it also provides support for the massive weight of the rear of the transmission. A roller bearing can do the first two but I don't think was designed to do the third. When I was considering using a fourth main roller bearing in 2010, I was talked out of it by many on this forum and elected to have the original babbited ball cap repoured by George King III of Engine Restoration of Connecticutt and fit to the machined shaft of the drive plate which I sent along with the ball cap. Also, the requirement for using the roller bearing that I cut 3/8" from the ball helped to seal my decision against using the roller bearing and opting for the babbited one. Jim Patrick
We install them on every engine we rebuild since the drive plate shaft is always worn. We've never had a problem with them. We purchase them from Kohnke Machine. Herm uses the original bell so there's no modification to the torque tube.