I'm about to resurrect my old 300x

[sharicasmi]

I gave up on it about a year ago due to being unable to track its vibration issues. I replaced the main shaft bearings this time, you just can't trust them to survive a couple of crashes. Main shaft feathering shaft, tail boom, main gear replaced. Going to mount a bar or a robird on it.
Are the kst115's any good? I pulled out my ds76s for use in a 250 and an ultralight/low hs 450. I'm interested in seeing if they work okay compared to stock servos.

[Neunerball]

The following thread might give you the information you're looking for
https://www.helifreak.com/showthread.php?t=492617

[DoubleCH]

Originally Posted by sharicasmi

I gave up on it about a year ago due to being unable to track its vibration issues. I replaced the main shaft bearings this time, you just can't trust them to survive a couple of crashes. Main shaft feathering shaft, tail boom, main gear replaced. Going to mount a bar or a robird on it.
Are the kst115's any good? I pulled out my ds76s for use in a 250 and an ultralight/low hs 450. I'm interested in seeing if they work okay compared to stock servos.

I use Align bearings for the mainshaft. Any bearings are better than stock bearings which are almost always toasted on a crash. I use Align because they are relatively readily available. My Align bearings have survived multiple crashes without getting gritty [knock on wood].

KST115 are top for robustness and reliability but they are heavy if you run stock or near stock power. I chose them early on to replace the crappy stock servos because I was having big time reliability issues with my 300X back then and I neededd to rule out the servos. Once I got the heli super reliable (I'm pretty much concluded the servos were the culprit) I decided to find cheaper/lighter alternatives parts and settled with HobbyKing Corona 918MP plastic gear servos ($4.5) and 919MG metal gear servos ($7). Both have interchangeable gear sets so I started off with all plastic gears because they are lighter and once a gear strip I replace with metal gear counterpart until all gears have been replaced with metal. That way 1 918MP and 1 919MG last at least 4-5 crashes that strip servo gears. However, once I put in metal gears I find I never strip them any more [knock on wood] so I think I'll probably just run all metal gears from now on. It's not that much heavier than plastic gear version and is still much lighter than metal case KST115s. The Coronas will get sloppy at a rate like any other single ball-bearing servos (KST115 with double-bearing will stay tighter longer) but I have had about 800 flights on the Coronas. Only now do I start thinking to replace my elevator servo (it's acting as part of my frame stiffener absorbing all the possible vibration from the main gear/shaft/rotor and crash shock). 800 flights for $7 I'm not complaining.

For details on KST115 (same as KST215 and TGY S306G) do a search WITHIN my flight log thread.
https://www.helifreak.com/showthread.php?t=503945