OK.. Who's idea was it to remove the throttle return spring?

[Tom Fiddler]

I understand that the Spectra's instructions say to remove the carb return spring.
Where did this come from and why?
In my opinion this is not a good idea... someone tell me why it is a good idea

[Tom Fiddler]

OK it's been 3 day's
Somebody take responsibilty for this!! :lol: :lol:

[bigrcr]

Actually, I did not realize that the instructions say to remove this spring. This is not a good idea. Removing the spring will promote accelerated wear on the throttle butterfly and through shaft.

I however, did recommend snipping the little loop off of the spring where is goes into the throttle plate. For our purpose this spring really serves no purpose other than to keep the slop out of the brass throttle shaft.

Somehow that question seemed directed at moi!? :dontknow :oops:

Later,

[Tom Fiddler]

No not directed towards you, just wondered why this was in the instructions and thought the instructions shoud be modified to remove this step.
I feel the return spring should be left alone as it will help to return the throttle to idle in the event of a servo/wire failure.
Also this slight spring pressure will keep the servo/throttle rod loaded and help reduce unwanted vibration
IMHO :lol:

[carey shurley]

it also places a load against the throttle servo gear train, and with the vibration will contribute to wearing the servo gears sooner.

John's right, you shouldn't REMOVE the spring, however unloading the pressure from the servo is a good idea.

As far as the pseudo fail-safe idea, it depends on how the particular servo behaves when it fails, and how it failed.

I can't find ANY references in the assembly manual about the spring, however the following is a quote from the operators guide which I wrote:

Also make sure the return spring has been unhooked from the carburetor body. Its tension will put undue force on the servo which is unnecessary.

[Tom Fiddler]

"it also places a load against the throttle servo gear train, and with the vibration will contribute to wearing the servo gears sooner."
I have to disagree, Just letting the gears vibrate back and forth against each other as compared to having a slight pressure in one direction to keep the gear stack "loaded" will accelerate the wear and increase the vibration to the pot in the servo.

Not to mention I now have this unloaded spring "rattling" around the throttle shaft.



"As far as the pseudo fail-safe idea, it depends on how the particular servo behaves when it fails, and how it failed."
True, but why would I want to remove ANY chance for the spring to help?

Well I guess we will have to disagree on this one and please don't take my question as a bad thing.
Just trying to share some thoughts and learn something

Thanks for your input

[carey shurley]

the good news - it will work either way, so if you want to run with the spring installed, no harm no foul!


A few observations might be helpful.

I have seen the spring actually help, when the servo arm has fallen off (because I forgot to install the screw). Other than that, throttle servo failures for me have meant a stuck throttle - spring or not
I've taken throttle servos apart, where most of the teeth around servo center were worn off the servo gears - using the spring. I personally haven't seen this when spring tension wasn't used.

of course, your mileage may vary!!

[Tom Fiddler]

"I've taken throttle servos apart, where most of the teeth around servo center were worn off the servo gears - using the spring. I personally haven't seen this when spring tension wasn't used. "

Well I can't argue with that! :D

Thanks for the info

[Brett]

And the conclustion is???????????? :idea:

[lakespinner2]

I've wondered why the glow engines don't use a spring (smilar to the gassers) for throttle closure if a link pops off. I was especially wondering about it as I watched an os50 screaming at full throttle with partial blades after a crash. :(

[bigrcr]

It is all in the design. The design for the Walboro carbs do include a spring and that is what is used for these motors (which are originally designed for lawn/commercial and some industrial use). The glow motors are not designed that way.

Later,

[Brett]

I simply put it in the loop at the other end so it does not flop around and make noise and it has no torstion at that end.

[carlos]

An old topic but a relevant one.
As John says
"I however, did recommend snipping the little loop off of the spring where is goes into the throttle plate. For our purpose this spring really serves no purpose other than to keep the slop out of the brass throttle shaft."

My perception of the spring is it provides torsional load to the butterfly and axial tension to the butterfly shaft.
the torsional tension is not needed and only applies load to the servo also transmitting vibs.(if the stop screw is removed as the instructions recommend the butterfly will close if the linkage pops off)
The axial load the spring applies to the shaft has got to reduce the vibration the butterfly shaft receives by taking any resonance out of it.

My way of thinking would be to snipping the loop off the spring. AS JOHN SAID
This still applies an axial load to the shaft and gets rid of the radial load to the servo. (which was my perception of the instructions and John's vid)

Wish I knew how ta spell. he he (good thing for spell check)