HunkaJunk

I have a 2008 AirWild hobbies 29% Extra 260 with Hitec 5645MG servos. Over many hundreds of fights, the gears in the servos have developed slop in them, particularly the Aileron servos. I initially replaced the gear trains in the servos and took care of all the slop. Then I noticed that new HS-5645MG servos for another project are noticeably faster than the old ones from 2008, I don't think by a lot, but I did notice the difference in speed so I ended up replacing them.

My questions are, Are the new servos known to be faster than the same model from 2008, or are my old servos showing brush/commutator wear?

I have good servo current meter, is there a documented no load current spec on the 2008 servos that I can test?
All servos are being ran off the same voltage (6.6 LiFePo4 rx battery)
Thanks much,

Xpress

Servos that are pushing nearly 10 years of age with a standard 3 pole brushed motor in them are eventually going to wear out with constant use. My advice to you is just to replace them with new servos, due to the age.

Personally, I do not feel comfortable recommending anything less than a steel gear servo (such as the D-954SW) in a 50CC bird and would have recommended something similar initially- even for non 3D flying. Engine vibrations alone can kill lower performance servos and as you experienced, put excessive wear on standard metal geartrains.

vertical grimmace

My Feedback: (1)

With this being the case, it seems odd that you would still have soo many large servos with Karbonite gears. Is there a warning with these servos not to use them with gas engines?

HunkaJunk

It turns out the reduction is servo speed after gear replacement was caused by my poor choice of servo gear grease as well as probably too much applied to the new gears. The grease was too thick and sticky and I applied too much on the new gear trains, cleaning them and using the proper grease at the proper amount resolved the servo speed issue and reduced the current load. As far as "constant use" I'm not sure about that term, although they do have more than 500 flights on them, they developed the slop in the gear train very slowly.

I'm not against replacing them, and I will, providing the plane lasts that much longer, but I see no reason to go drop $500 or more on an obsolete ARF when I have 2 more the same size that are set up with much stronger (and expensive) servos

Xpress

We actually have a specific grease we recommend and you can purchase it from Tower:

https://www.towerhobbies.com/cgi-bin/wti0001p?&I=LXN741&P=7

That small tube can do a couple dozen standard sized servos- you just need a very light coating on the gears to get the job done.

Yes actually, we specifically advise against using karbonite geared servos in gasoline airplanes. They work great in smaller applications like electric or glow sport airplanes.