Please Explain Gearbox Types

[Spongebob]

Live Long and Prosper Earthlings,

I have now heard of B, C and E gearboxes.

Unfortunately I have no clue what the diffirences between them are.


Could someone help my out of my misery regarding this.

[Duck Rogers]

Here's a basic overview.......there may be other differences also between the boxes, but you'll get the picture anyway :D

The B box is easy to identify as you have six nuts/bolts holding the two halves of the box together.
They are (were) availble in two types: the provision 4 which has an adapter plate bolted to the engine and the gear box bolts to it, and aprovision 8 which uses 8 bolts and NO adapter plate - the box bolts
directly to the engine.
The B Box is also regarded as a lightweight box and is probably best suited for props with a length of 66" or less. Also has no "rubber donut" damper.

Then you get the C and E boxes. Designed for longer/larger props with more rotational mass. These have a series of small allen screws holding the gear box halves together, and have a "rubber donut" damper between the output shaft and gear box to absorb the loads that the larger props are placing on the engine. The E box is basically a C box but has a built in electric starter and is the best in my opinion.
The C and E boxes are regarded as heavyweight boxes. (not because they're heavier )

The boxes are also offered in different gear ratios.

There is also an A box which is no longer manufactured.

Spongebob.....you can stop being miserable now :D

[Tobie]

Question, what is the best oil to use and how often replaced? E-box.

[Duck Rogers]

...what is the best oil to use and how often replaced? E-box.

The Rotax spec calls for a gear oil with a rating of API-GL5 or GL SAE 140EP or 85W140EP. Usually any good gear oil with a "weight" of 90 or higher will do just fine. Get it at your local petrol station unless you want to stick to the specs and go and buy moerse expensive Castrol stuff.

If you have a new box, replace the oil after the first 10 hours of operation and thereafter every 100 hours