Page 5

It's time to reassemble the engine

The original economy steel bearings are replaced with HP stainless steel. Also, the prop hub bearing is a factory sealed and permently lubricated as well. Bearings are reasonably inexpensive depending on what style and class bearings you choose. The bearings you get from a hobby shop are usually OEM (Original Equipment Manufacturer) economy class.  These are OK, but for half the price you can upgrade to Stainless Steel High speed High performance bearings! The advantage to stainless steel is they don't corrode, they're smoother rolling bearings, and they have less axial/radial run-out. My source of bearings is Boca Bearing. They specialize in bearings and have a monster selection to choose from, for just about every R/C engine ever made. You have the choice to go from Economy class all the way up to State of the Art Ceramics. http://www.bocabearings.com

Let's talk about inserting bearings for a moment...
You may have noticed that I use heat on the crankcase to extract and install bearings. There's a reason for this! I have a bearing press, but 99.5% of the time, the bearings do not align up perfectly! Perfect bearing alignment is CRITICAL for long bearing life and maximum engine performance. Heating the crankcase bearing supports expands the metal beyond the bearing size thus allowing the bearing to rest in a straight line relative to the crankshaft. You'll also notice that I use the crankshaft for my insertion tool. You can't get any more accurate than this for bearing insertion! Should you force a bearing into your crankcase (IE: pounding them in) you may as well throw your engine in the trash, because it won't last long...

Place the new hub bearing on the crankshaft as illustrated in the photo. This bearing (hub bearing) is the first to be installed. Heat up the bearing support   on the crankcase with a torch. It doesn't take much heat to expand the metal, so go easy on the torch!

With the bearing support heated, insert the crankshaft on the outside of the bearing support and carefully seat the new bearing. If the bearing doesn't readily drop in, apply more heat to the support. Do not heat the housing with the bearing still sitting there, please!

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