AT-160 gearbox.

General info:

The gearbox is designed for 4-stroke auto-moto engine conversions up to 165HP and using them with propeller for NOT SERTIFIED experimental light aircrafts, hovercrafts, airboats etc. It can be used for tractor and pusher layouts. TBO is more than 1000 hours. It is recommended to check and possibly change bearings and rubber dampener after 1000 running hours.  

The gearbox set consists of:

1)    2 halves aluminum body with helical gears and bearings in oil inside, and 2 shafts – drive spline shaft and driven propeller shaft

2)    Spline rubber damper adapter + 6 hole Mercedes damper (big or small)

3)    Hardware

Available gear ratio 2.0; 2.3; 2.5; 3.0 This gearbox is light and more compact than previous SPG models, with more strong gears and bearings, easier to assemble (because of the spline shaft) and do preflight checking.


The gearbox conversion kits include bellhousings and crankshaft-dampener adapters (or flywheels machined together with dampener adapters) different for different engines. They can include other conversion parts, for example starters, modified oil pans etc.


Assembling and installation info:

Assembling and installation on the engine is quite simple procedure. No necessity to modify your engine to install the gearbox. Step-by-step assembling pictures will be at Airtrikes website soon. E-mail Air Trikes Ent. if you are not sure how to assemble it. Some important notes:


1)  Some engine components can be different. For example, there are 2 different types of starter flywheels + automatic flex plate for Suzuki-GEO engines.  It is also possible to use a custom made flywheels. We supply crank coupler and flywheel spacer which can be used with an automatic flexplate. If you want to use the flywheel, it has to be machined. We supply necessary drawings. Or you can order an aluminum light flywheel


2)  In most cases the conversion kit comes with all bolts and other necessary hardware. If you buy only the gearbox kit to adapt it to your engine, you will need crankshaft and bellhousing bolts. You can buy them (at least 8.8 grade) in a local hardware store. Metric bolts are not common in Canada and US. The best hardware supplier we could found in the US and Canada is FASTENAL company.


3)  Torque crank bolts sequentially with 5 ft. lb. increments to 45 ft lb (or following your engine specs). Torque engine and starter bolts following your engine specs (37ft lb bellhousing-to-engine and 17ft lb starter for GEO-Suzuki). Torque rubber damper bolts to 45 ft lb. Torque bellhousing bolts 17 ft lb Use blue locktite to secure bolts, safety wires for plugs.


Gearbox break-in:

Must be done with a propeller.


1) Fill the gearbox with gear oil 75W90 or 85W140 50ml more than the level of the side plug.

2) Start the engine. Run it from idle, slowly increasing RPM up to MAX for one hour.

3) Stop the engine, pour the oil out, clean the gearbox inside with kerosene (diesel oil).

4) Check the torque of all bolts, reinstall loosen bolts following assembling instructions.

5) Fill the gearbox with fresh gear oil 75W90 or 85W140 again 50ml more than the level of the side plug. Install security wire to each plug

* Gearboxes can “throw out” some excessive oil through the vent plug.    


Gearbox maintenance:

Check the gearbox visually during pre-flight outside (oil leak, cracks, safety wires) and inside through the windows (rubber damper, crank and damper bolts, cracks of the shafts).

Change the gear oil each 50 running hours or one year.

We don’t recommend opening the gearbox if there is no strong necessity for it. It is quite easy to damage seals or other parts during incorrect disassembling and reassembling. Allow the manufacturer or “Air Trikes” to do it if necessary.


Recommended propellers for Suzuki-GEO engines with AT-160:


 Reduction Ratio

KOOLprop model

G10 carb and TBI



G10 carb and TBI


63” 67”

G10 TBI “Sport”


67” 69”Light

G10 Turbo


69” light

G10 Turbo


69” heavy

G13 BA


67” 69”Light

G13 BB


69” Heavy 73”



69” Heavy   73”


If you have any questions - contact Air Trikes Enterprises. E-mail:  Phone number: (450) 202-7772  Website or one of our local dealers closest to you.


Gearbox installation pictures (Suzuki G10-G13)



Engine installed, transmission part clean. Transmission pilot sleeves installed


1)    Prepare the gearbox kit, flywheel, starter, instruction, dyno wrench, thread locker (blue locktite) and other components if necessary.



2)    Check the crank bolts’ length (6 M10x1.25). Cut them if necessary. Install flywheel and crank adapter on the crankshaft (with crank spacer if necessary). Use blue locktite.



3)    Install the rubber damper to the gearbox spline adapter (6 M10x1 bolts) Use blue locktite. The cylindrical part of the adapter can be inside the damper for other installations.



4)    Install the rubber damper assembly to the crank adapter (3 M10x1.25 bolts) Use locktite.



5)    Check the starter installation. Make sure you have pilot sleeves (2 tubes diam 11mm for G10-13-16). As we often use aftermarket starters, some starters need to be fit to the flywheel. Install the starter, make sure it fits well, then remove it.


6)    Install the bellhousing to the engine (4 bolts M10) Use locktite.



7)    Install the gearbox to the bellhousing (6 bolts M8 and 2 bolts M10) Use locktite. Don’t orvertorque the bolts. Assembling can be done step 7 then step 6.


8)    Install the starter to the bellhousing (2 bolts M8) Use locktite. Check the engine cranking. Fill out the gearbox with transmission oil. Install the plugs. You are ready to brake the gearbox in.


As you can see – nothing difficult. All mechanical part of the conversion could be done for about half a day. The same way it can be installed to Suzuki, Subaru, Honda, BMW engines.


Available options:


Machined manual flywheels, as well as aluminum light flywheels.




Canister-type muffler G10 G13 (regular and stainless steel)

1)Set of 3 light aluminum hard anodized pulleys. The alternator pulley is the same diameter as other pulleys


2) Light alternator with installation bracket. About 2lb lighter than the lightest standard GEO alternator with its bracket.

Motormount L-bars (2, each side) with 6 Barry-mounts.


Other options, the same as ready-to-install engines are available.


If you have any questions - contact Air Trikes Enterprises. E-mail:  Phone number: 450-202-7772