Vibrations 2000-3000 RPM on final

Re: Vibrations 2000-3000 RPM on final

by Garrett Wysocki » 6 years ago

Garrett Wysocki

1 572 1.45k

Check that the piston under the diaphragm moves easily and down. I had the same thing happen and I just cleaned and re lubricated the internal bronze bushing that keeps it centered.

Re: Vibrations 2000-3000 RPM on final

by Bill Hertzel » 6 years ago

Bill Hertzel

13 1.95k 8k

What Engine?
What Gearbox?
Clutch?

There is a middle ground where during part of the rotation cycle the Propeller outruns the Crankshaft and on the next Power stroke the crankshaft catches up. Slack-Bump-Slack-Bump...
At High power, the prop slows down fast enough that no slack occurs.
At Low power, the forces are so low as to be unnoticed.
It is only in the middle power settings that the prop and crankshaft get into a fight.
On the ground, the prop is always pushing air.
During the glide on final, the prop becomes unloaded due to the relative wind.

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Bill Hertzel
Rotax 912is
North Ridgeville, OH, USA
Clicking the "Thank You" is Always Appreciated by Everyone.

Re: Vibrations 2000-3000 RPM on final

by Jacques Foucher » 6 years ago

Jacques Foucher

19 109 248

I also have a sync problem at 3000 rpm
How do you clean and lubricate?
What oil do you use?
Thank you
Jacques

Re: Vibrations 2000-3000 RPM on final

by Jacques Foucher » 6 years ago

Jacques Foucher

19 109 248

I wanted to talk about the piston above the diagphram, and Garrett's solution

Re: Vibrations 2000-3000 RPM on final

by Garrett Wysocki » 6 years ago

Garrett Wysocki

1 572 1.45k

My problem started after Lockwood installed a new fuel pump after a gear box service/inspection. Initially the new pump was over pressurizing and caused the carburetors to flood and then the engine would vibrate and shake after the power was pulled back on final. I called Joe at Lockwood, described the problem and he immediately suggested check the slides, he said that the flooding washed away any lube and the blue dye left over from the 100LL would cause the slides to stick unevenly causing an out of sync condition. I cleaned the bronze slider bushing with mineral spirits and then re lubed with engine oil. The engine ran better than it had in a while as I think the carbs were staying perfectly synced with the sliders moving freely because of fresh lubricating oil. If you take the diaphragm and top of carb off make sure when reinstalling to put the alignment tab on the diaphragm back in the proper position so the slider is properly aligned.