hi all, can u use fuel pipe tubing as a throttle return spring? ive heard u can

cheers

sam

Yes you can and also you can use the spring that comes in the retractable pens

what like a BIC pen?

Well just make sure it works.. I dont know if a pen's spring has enough power to push the servo if it dies..

ram

Like he said make sure it works I had some pens around here because my mom has a office suply store, and they had a pretty strong spring even stronger than the one it was supplied with my r40, In my 710 I dont know what kind of spring it came because in the box it didnt came , but I put one of those spring and I have a 90 oz servo and it does the job.

cool, but whats best? the spring or the tubing?

I definitely use fuel tube for the brake linkage because I like the positive force.

I wouldn't use tubing on the throttle linkage because you shouldn't need the extra force. In addition, when you're braking, something stiff like tubing on the throttle side will diminish braking force and tend to wear out your servo quicker.

so just tubing on the breaking, no springs? how long should it be?

cheers

i have an even better idea, buy an actual throtte return spring

There are several methods that I have used over the years, I now run a full PCM system and have not needed a physical fail safe for some time.

In the past I have used a rubbber band wrapped arround the carb (slide carb) and carb body....easy quick fix and it worked great.

I have also used various types of springs but never got much out of the fuel tubing idea, I guess it works for some. Tower does sell a variety of throttle springs that are very cheap. Might be good to toss one onto your next order.
[link=http://www2.towerhobbies.com/cgi-bin/wti0095p?FVSEARCH=Throttle+spring&FVPROFIL=++&sear ch3=Go]http://www2.towerhobbies.com/cgi-bin/wti0095p?FVSEARCH=Throttle+spring&FVPROFIL=++&sear ch3=Go[/link]

The main idea is for the spring to offer enough pull to bring the servo arm back to a neutral position closing the carb, without so much force that it accelerates wear on your servo. The best way to test is to move the servo to full throttle (without engine running) then the spring should pull it back with some authority.


Keep in mind that the throttle return spring will not protect from others stepping on your frequency, if someone steps on yours with WOT it is gone. PCM or a seperate failsafe unit is the best overall option for all situations.


Dbow

Somebody correct me if I'm wrong but the throttle return spring is not necessarily meant to pull the servo back in case of radio failure. It's meant as a return for a mechanical failure. I've had the throttle pop off the ball and the return spring did it's job.

gunna order this one:



any good?

Actually they are, Throttle return springs are meant to pull the servo arm back during radio failure. One of the most common events that I have seen is for the battery to disconnect or actually come out of the model. I have seen it quite a few times at the track, cars take off WOT with the battery pack dragging behind them. There are other situations as well.

The spring can also protect against an actual failure where the rec. for whatever reason quits sending input to the servos. Like you say they do also protect against linkages coming loose or breaking etc.

What they will not protect against is someone stepping on your frequency, I do not consider this a radio failure because nothing in the electronic system has actually failed. Someone basically turns on a radio that is on the same frequency and it causes your radio to loose control. Glitches and things of this nature also will not be prevented by the spring.
Bottom line is that any time the servo is under power the spring is null. It can only function when power is not applied.


Dbow