Redrive lubricant maintenance
by Had Robinson
There are two models of the Top 80 redrive. For older models (before 2004), refer to part B below. For newer models, refer to part A.
A. Current redrive models
For models manufactured after 2004 (with fill and drain plugs), Miniplane recommends 50 ml (1.5 fl. oz.) of 80W-140 gear oil. 100% synthetic 75W-90 gear oil may also be used. The redrive is a simple set of helix gears so oil grade and quality is not particularly important so either choice of oil is more than satisfactory.
As Miniplane notes, replace the redrive oil after the first (10) hours of use and yearly thereafter. Be sure to clean the gunk from off the magnetic tip of the drain plug.
- small measuring cup
- a syringe OR a short piece of narrow tubing e.g. a WD-40 spray can tube and a small funnel
If you attempt to pour the oil into the redrive, even with a small funnel, it will go everywhere. There must be some way to let air out as the oil goes in. The small tube found on spray lubricant cans works fine for this. Insert the tube AND FASTEN IT with tape so it does NOT drop into the redrive. If you have a syringe, use it. It is the easiest way get the oil into the redrive.
Remove the fill plug. If you do not remove it, the oil will take a day to drain out.
Drain the oil from the redrive by loosening the drain plug on the bottom of the redrive. Do not lose the small aluminum washer that goes between the plug and redrive. It will take at least 15 minutes. (If the fill plug is in place, remove the drain plug first, place a can under the drain hole, and then remove the fill plug.)
Reinstall the drain plug.
Fill the redrive with new oil and replace the fill plug.
Properly taken care of, the clutch and redrive will be trouble free for your flying career.
Those who fly in damp climates must be particularly careful in keeping the oil fresh and occasionally running the engine up so as to keep the metallic surfaces well coated with oil to prevent rust. Rust in oil is a severe abrasive (iron oxide).
B. Redrive model made prior to 2004
The maintenance schedule for these redrives is about (5) years or when the drive starts to make excessive noise. Older models of the redrive use grease rather than oil to lubricate the gears and bearings. They do not have a fill or drain plug but a single breather tube located just above the clutch housing. They must be disassembled in order to replace the grease. See Mark Kubisch's service notes for instructions on how to do this.
Older model Top 80 redrive (before 2004)