Hydro Lurch
 

Usually when I find a Cub that Lurches or jumps in acceleration when the springs and end pins are okay, I will find one of two problems.

1. The Trunion bracket has a notch worn in the end of the bracket.

https://s25.postimg.cc/g5bo9inb3/Hydro-_D.jpg

https://s25.postimg.cc/rwzjkbhxb/Hydro-_E.jpg

2. The side bracket and the trunion bracket have been painted or there is rust between them that does not allow the two brackets to move independently.

3. The control linkage has worn or sloppy parts. Close and careful examination of this linkage is needed.
Replace any/all worn parts.

https://s25.postimg.cc/b7y3oelbz/782-_A.jpg

Whenever you move the hydro control quickly either forward or reverse the side plate responds immediately with only the small spring causing the trunion bracket to follow with a slight lag to reduce the quick change, when you reach the point of the large spring taking over it is direct movement.

If you have rust between the two brackets or someone paints the brackets they are linked together and you will not like the results, that is what the two different springs are for.

Another problem when the trunion bracket has a notch in the end the end pin will catch momentary and then snap free causing erratic operation.

Another problem, is a bent Speed Control Arm. Examine and make sure the arm is plumb and has correct geometry.

https://s25.postimg.cc/cpjjzyq2n/Hydro-_B.jpg

You should be able to hold the trunion bracket and move the side bracket back and forward and feel the smooth movement and the point where the big spring takes ov

https://s25.postimg.cc/ndnayt01r/Hydro-_A.jpg


Information supplied by:

Richard Christensen
Roland Bedell