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Sep 03, 2018, 03:36 PM
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MKS HBL 990+Trex 760x Tail Alignment Issue

Do you guys happen to know if the MKS HBL 990 servo control arm spur gear is in a slightly different location than the Align tail servo spur gears?

Here is the reason I ask.

I cannot get the Trex 760x tail control balls links threaded onto the tail pushrod far enough to be considered secure without screwing up the 90 degree servo arm vs blade angle geometry. What I mean by this is if I adjust the ball links properly, where the tail servo control arm is at a 90 degree angle and the tail blade tips are in alignment, the ball links are about to fall off of the threaded rods on each end of the tail control pushrod. In order to get the tail blade tips to align properly, I have to add sub-trim to the MKS servo which creates a 10 or more degree offset in the servo arm from the normal 90 degree orientation.

I have checked everything I can possibly think of.....correct ball links are installed, the pushrod is indeed for the 760x, the tail servo is mounted correctly etc..

The only two explanations I can think of is either the 760x tail control pushrod is slightly short from the factory or the MKS HBL 990 servo's control horn spur gear is slightly more toward the center of the servo than the Align servo.

Any advice would be greatly appreciated.
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Sep 04, 2018, 03:25 PM
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sawacs's Avatar
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Problem figured out.... The tail control rod for the Trex 760x is 5/16" shorter than it is supposed to be and explains why I am unable to get the servo horn and blade tips centered..

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