Ernst offers a selection of kits to regear most Athearn diesels with a 3:1 gear reduction. While the instructions contain photos of various steps, they require a good deal of study to decipher the procedure. For the price, the results are more than well worth the effort. Over the years club members have redone over 20 locos successfully, along with an unknown number of customers.
A white or light colored work surface and a good light is best, since most parts are black. Identify, separate and lay out parts. Disassemble one truck, remove recommended, unused parts and lay aside. Lay out kept parts in perspective. Keep second truck partially assembled for reference and to avoid mixing parts. Athearn's exploded diagram is very helpful during analysis.
Although Ernst parts are usually very clean cast, each should be inspected under magnification. Using the back edges of a #11 blade, carefully scrape any irregularities smooth. Do the same with any reused Athearn parts. Check any metal shafts for burs or roughness due to oxidation or machining. Polish with fine Crocus cloth or rouge, if necessary. Start reassembly checking for excessive side play and shim with NWSL thrust washers. Since several may be needed in many applications, buy the 100 pack and save. After assembly, without the worm, check each truck for binds by turning each wheel and the worm wheel. Locate and correct any binds. The worm shaft may also need some thrust washers added, during reassembly. Keep in mind that most noise is generated by vibration of loosely fitting, moving parts.
Check motor with fly wheels but without splines. Check end play on open motors and add shims for minimum play. A VEE, resembling that of a "C" snap clip is cut in a nylon or bronze thrust washer and inserted between mounted washers by snapping over shaft. Lubricate bearings, even on cans. Labelle 101 is best, if careful. If in doubt use 108. Run and listen to pitch (speed) for increase. An infinitesimal drop of 101 applied to the commutator, will increase pitch very noticeably by reducing brush friction .
CAVEAT: Labelle 101 can and
will soften or dissolve styrene and other plastics. Nylon, acetals
and most acryllics are immune. Some commutators may contain plastics
or cements that may be affected.
Adjusting brush pressure is not normally recommended, unless there is an absolute need. Be sure you have spare springs, before ruining old ones. A well tuned ear or tachometer is a must in this type of tuning. I never replace Athearn motors with cans in spite of hype. Dependent on wheel diameter, at 12 V., older motors produce about 160 SMPH, while newer produce about 106, both with sufficient power, in spite of current draw. Expected speeds should be about 53 and 35 respectively.
All new locos require a breakin period, running light. Since parts are Delrin Acetal, which is considered self lubricating, run loco dry, in both directions, on a loop for a couple of hours, if necessary, at 12 - 15 V. You may want to check progress periodically by testing low speeds and acceleration and coasting. When satisfied lubricate shafts with Labelle 108 and gears with 102. Do not neglect the worm and bearings. Applying 102 to the gear faces and thrust surfaces, helps reduce side play and noise. Run for about 15 minutes, each direction to distribute the lube.
Even though the process seems tedious, we have achieved excellent results. Our practice has been to talk each doer through the, sometimes confusing, method and each has been successful.
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