karolh

Though this might be considered a bit off track please bear with me here. I have a EI G23 powered Carl Goldberg Extra 300 built in 1995, which is still being operated on the five original Futaba S148 std servos, which were upgraded when new with a BB top cover.

The model has never suffered any crash damage and the servos all work perfectly. However due to their age and the fact that servos technology has improved quite a bit since then, I am wondering if I should replace them, even though the model has had maybe only 40 or so flights to date. Your thoughts please.

Karol

arobatx

This will be interesting to see all of the replies Karol Hopefully those who have had some older 33%ers speak up about what servos flew hundreds of hours in them without problem! One person I would highly recommend talking to about this, would be Dick Hanson. He will give you a very down to earth view about this, with lots of experience to back it up. I've had similar conversations with him about this.

Chad

pe reivers

I'm watching

karolh

Thanks for that link Chad, sending you a PM.

Karol

Tired Old Man

My Feedback: (1)

The 148 was a great standard servo for it's time. Personally, if the plane flew the way I liked it and the gears in the servo were still holding up I'd leave them. You really don't need to suddenly stuff a 6v system in the Cub, faster servos aren't going to gain any performance boost, and the flight surfaces are lightly loaded so they don't need metal gears.

Why change?

karolh

Pat, thanks for you input which pretty much aligns with my thinking, but I needed to hear from those more experienced and knowledgable than me. By the way the model is a 68" CG Extra 300 and not a Cub.

Are there any real tell tale signs that one should look for in a servo when it is reaching the end of it's time?

Karol

Tired Old Man

My Feedback: (1)

I was distracted, forgive me, Extra it is Extremely poor centering, which could also be a dirty pot, jerky linkage motion indicating broken gears, stuck output shaft, "hunting" for center, are all indications for a worn out servo. Typically the 148's would break a gear during an impact before they actually wore out, and when they wore out they simply stopped moving in the last position they were in.

A truly great product in it's time. Airtronics had a servo of similar quality during the same period.

NM2K

My Feedback: (14)

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The old addage, "If it ain't broke - don't fix it", has a lot going for it as far as I'm concerned, Karol.

I ran the same servo set up as you have for many years in highly stressed airframes. Never a single failure.


Ed Cregger

karolh

Thanks all. So far none of the traits Pat highlighted have surfaced, but I will certaintly keep a very close watch on them, as it would be a lot less painful to replace them than lose the model due to a faulty unit.

Karol

arobatx

Do you remember the old JR 507 servo? I can't tell you how many planes those old suckers flew without any problem. Then the ball bearing shaft supported version surfaced, the 517. We thought we were in heaven. I tell ya...more times than I can count, I have seen (and used) servos like the good ole 517 similar to the S148 futaba, in planes significantly larger than what you've got questions about, without problem. It was all in the setup, mechanical advantage, zero slop linkage...etc. The newer high powered servos do offer outstanding power, precision and speed...but at an even bigger cost if your setup isn't right

Chad

Rcpilot

My Feedback: (78)

If you have $400 lying around and you are suddenly going to start flying IMAC, then replace the servos.

Otherwise, leave it alone and fly it.