Rotax C drive, Rotax c reduction drive, RK 400 clutch for Rotax C drive, clutch for Rotax drive.

Rotax C geardrive for rotax 447, 503, 582, and 618 two stroke aircraft engines.

Rotax C Geardrive For Rotax 447, 503, 582, And 618 Two Stroke Aircraft Engines.

Type C gear box is totally different internally and externally than the A or B Drive. It dampens torsional vibration via a rubber "Hardy Disc" rather than bevel washers. The C drive also weigh about 10 pounds more and is more expensive. 

The C drive can handle considerably more "mass weight inertia", and is available in ratios of 2.62:1, 3.0:1, 3.47:1 and 4.0:1. The C drive is used with larger diameter props, or propellers with more blades.

For example a WW 1 replica fighter using a 582 engine could swing a very large two blade prop very slowly using a 4 to 1 reduction drive. This would be more authentic looking, be very efficient and quiet. But this combination would not work well on a very fast plane, or one with an aircraft thsat has low ground clearance.

A trike could use a 6 blade prop, with less length and more pitch for the same reasons.  In Europe it is quite common to find A C drive used on trikes with 6 blades and a 4 to 1 reduction ratio, just for the fact that the combination is VERY quiete. 

While some in the industry may  argue that this allows the use of smaller engines to be used, with the larger ratio. Real life has shown that a prop and its power are mated with the craft. That is while you may find some craft can fly on less power, using a larger redrive ratio - it is always better to have MORE power.

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Rotax C drive clutch

Rotax C Drive Parts Diagram
No one will ever dispute the fact that a 2 cycle engine is not happy at very low RPM's with a large flywheel attached to its PTO end. The flywheel of course is the propeller. This dissatisfaction is usually responded to with severe shaking and rough running.
This action can be easily proven by simply removing your propeller from your gearbox and then start your engine.

A clutch is available for the C drive which makes the engine easier to start, and is recommended for float equipped aircraft.

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Rotax C drive radiator mounting bosses

Rotax C Drive Radiator Mounting Bosses

The Rotax C Gearbox is designed  to bolt-on to any Rotax two stroke provision 8 crankcase aircraft engine, such as the Rotax 447, Rotax 503, Rotax 582 and Rotax 618.

The Rotax C Gearbox uses an internal rubber Hardy Disc help eliminate vibration and impulses from prop and engine. The C gearbox can handle "mass weight intertia" of propellers with a length of 72 inches and  three blades. 

If in doubt about the prop you wish to swing on this box refer to Part #31 Measuring Prop Inertia for more information. Total weight of the C gearbox is 17.6 lbs. 

Note: the large diameter holes on each side of the gearbox are for inspection of the rubber hardy disk. These holes are to be left open. The threaded mounting bosses on the C Drive are for installing a Rotax twin factory radiator system. .

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Normally C gearboxes were shipped from the factory with the following parts:

Rotax C Drive Parts Diagram

C gearbox parts checklist:
1@ - #944-140 Prop Plate
1@ - #944-110 Breather w/ Gasket*
1@ - #840-270 Magnetic Drain Plug*
1@ - #552-280 Gasket Ring
11@ - #241-811 Allen Screw 6x35** (some may be holding case halves in place)
11@ - #945-751 Lockwasher 6mm
8@ - #440-366 Screw 8x90 (29 ft lbs)**
1@ - #841-590 Allen Screw 8x35**
1@ - #845-310 Lockwasher
1@ - #958-980 Flywheel
1@ - #958-960 Hardy Disc (remove & discard steel clamp only after Installation)
1@ - #958-970 Coupling Flange
6@ - #841-820 Allen Bolt 10x45**
6@ - #944-120 Washer
1@ - #841-651 Hex Screw ½-20 x 30**
1@ - #827-785 Washer
1@ - #13001 Loctite 242 Blue
1@ - #9552 Anti-Seize 1 oz. Tube
1@ - Cutter Blade
1@ - Installation Instructions
*Safety Wire all ports before operation
**Loctite 242 Blue on all these fasteners
*** Fill gear box to lower of two side plugs  

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