At about 45 hours I installed the upgraded gearbox in my Viking 130 powered Zenith 750 Cruzer. Jan had told me that the new gearbox would run cooler and had a new bearing to handle the turbo power levels, and since I was contemplating getting a constant speed prop, I thought the extra headroom would be worth the investment since constant speed props run higher RPMS.

I have about 15 hours on the new gearbox and I have to tell you I am surprised how cool in runs, how much cleaner the new setup is to deal with the oil changes and the elimination of the Gear Box Oil overflow and the new sight glass makes it far easier to get just the right amount of oil in and check on the color and quantity easily. 

The major differences:

1. New bearing design.

2. New filler port. Wider and with a large cap.

3. Self contained vent.

4. No overflow bottle or external tubes.

5. Sight glass to see oil level and oil color. 

6. Relocation of temperature probe to top of case.

6. My new drain plug did not have magnet on it. Not sure if that is intentional or not.

I really never perceived any problem with cooling in the original gearbox and the only issues I had had before was I had once inadvertently overfilled the GB with oil once because I was worried about not getting enough and had added extra to the overflow, that flowed to the gearbox on a hot day while sitting between flights. I then had high oil temps on takeoff return to the airport and changed the oil and found I had put 12 ounces instead of the 6.The temps returned to normal on the next takeoff. With the new gearbox, this situation would have been entirely avoided since I could see the levels, and I have no prospect of overflow oil coming back in, or oil migrating to the overflow.

The one thing I really notice is the gearbox oil temperatures are so well controlled on the new box that during the oil changes the oil looks almost as good as when I put it in. On the old gearbox it would always come out darker.

I have no regrets springing for the new upgrade. It was well worth the time and effort and has given me even more confidence int what I already considered an excellent power plant. 

Jonathan Fay


New larger fill cap.

Sight glass.

No overflow!

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