Throttle servo choice

[Rodney Kirstine]

The 120srx is a pita for throttle linkage setup.  I was running into the same thing using a BK mini servo, even.  I ended up using the FBL rotors ball studs and links and putting the ball on the outside, even though it puts the linkage at somewhat of an angle.  Those ball studs are a little taller so it is able to travel without binding, even at the angle.

Now that I think about it... I might try one of the really long ball studs, from the swash plate, on the engine's throttle arm to move it out more in line with the servo arm.

[Chris Wall]

Funny you mentioned that, I just took the OS throttle arm (since it is a little stouter) and drilled it out with a 3mm bit!  The long balls off the swash seem to bring it out quit a bit!!!  I also was just reading a thread here where several were using the tail blade spacers to bring the YS arm out to help the geometry...

The 120srx is a pita for throttle linkage setup.  I was running into the same thing using a BK mini servo, even.  I ended up using the FBL rotors ball studs and links and putting the ball on the outside, even though it puts the linkage at somewhat of an angle.  Those ball studs are a little taller so it is able to travel without binding, even at the angle.

Now that I think about it... I might try one of the really long ball studs, from the swash plate, on the engine's throttle arm to move it out more in line with the servo arm.

[jluthe1]

If you really want a super fast servo consider the BK servos.... The red tail servo is .03, and of course HV and costs only about $100.

[Chris Wall]

I do have a RJX one that I could use, but more concerned with the case hight and the RJX/BK cases are pretty large.  I am happy with the Torq, it is just the clearance (worked great on the OS).  And if I remember correctly, the vbar doesn't like 760 tail servos for throttle?

If you really want a super fast servo consider the BK servos.... The red tail servo is .03, and of course HV and costs only about $100.

[jluthe1]

Sorry but I haven't actually tried it for the throttle but the new version tail servo is actually a bit smaller than my savox 1290 tail servo and almost twice as fast... Never seen mini vbar have issue with the bk servos though , that being said mini vbar doesn't really like nitro 😖

[Chris Wall]

Sorry, I am using a full sized silverline vbar, but what I meant was - I am pretty sure the vbar wants  a 1520us servo on the throttle channel.  I believe that the BK tail servo is 760us so, I didn't think it was possible to use...

Sorry but I haven't actually tried it for the throttle but the new version tail servo is actually a bit smaller than my savox 1290 tail servo and almost twice as fast... Never seen mini vbar have issue with the bk servos though , that being said mini vbar doesn't really like nitro 😖

[Mike King]

I can confirm using 4 of the tail blade spacers works like a champ with the YS 91 Tareq.  Using the standard linkage balls and no rubbing on my Align DS620 case.

[Chris Wall]

Out of curiosity, did you shorten the servo arm to match the YS arm (14.5mm) or leave it at 16mm per the manual?

I can confirm using 4 of the tail blade spacers works like a champ with the YS 91 Tareq.  Using the standard linkage balls and no rubbing on my Align DS620 case.

[mdu6]

Typically you want the servo and engine arms to be of the same length.   16mm (servo and OS arms) surely leads to a good ATV/geometry - hence the recommendation from the manual.

On the YS, the longest engine arm hole position yields about 14.5mm - this is what I used on my mini-servo setup and obtained a good travel geometry (+100 -100).

[Mike King]

I am not using the furthest hole out on the Futaba 4 star arm.  Mine is on the 3rd hole from the center.  This gave me servo resolution of a bit more than +100/-100 for full throttle to engine quit with my radio trim all the way down.

[jluthe1]

Sorry, I am using a full sized silverline vbar, but what I meant was - I am pretty sure the vbar wants  a 1520us servo on the throttle channel.  I believe that the BK tail servo is 760us so, I didn't think it was possible to use...

Sorry but I haven't actually tried it for the throttle but the new version tail servo is actually a bit smaller than my savox 1290 tail servo and almost twice as fast... Never seen mini vbar have issue with the bk servos though , that being said mini vbar doesn't really like nitro 😖

The internet definitely agrees with the 760... But I'm almost positive my buddy has a new full size version with the motor inside the case and it might be 1520... I'll have to wait til tomorrow afternoon before I can see him and the servo still in its box. I'll let you know.

[Rodney Kirstine]

I have both standard and mini BK and RJX servos and the link will not clear the top of the case on any of them if you set it up with the ball facing the servo (with the 120srx).

[jluthe1]

I have both standard and mini BK and RJX servos and the link will not clear the top of the case on any of them if you set it up with the ball facing the servo (with the 120srx).

Guess the 760/1520 issue is a moot point if they won't fit anyway 😥 sorry it can't work for you, but I'm still gonna check for curiosities sake 😁

[Chris Wall]

Guys, thanks for all the help!  I was able to get the Torq servo working pretty good (not perfect), but enough to run a few tanks of fuel through it today.  I added 4 of the tail blade spacers (and a longer bolt) to space out the YS arm from the throttle barrel.  I also, drilled the hole in the arm out and used a FBL swash ball to the YS throttle arm which gave me enough clearance on the servo case (might be rubbing a tad, but enough to start breaking in motor while looking for a better solution) using the 14.5mm spacing on both sides.  Push come to shove, I could mount the servo from the inside allowing me to mount ball pointing out instead of in on the servo arm...

[jluthe1]

I have both standard and mini BK and RJX servos and the link will not clear the top of the case on any of them if you set it up with the ball facing the servo (with the 120srx).

Guess the 760/1520 issue is a moot point if they won't fit anyway 😥 sorry it can't work for you, but I'm still gonna check for curiosities sake 😁

After looking physically at the servo.... I was wrong, there is only one tail servo available from BK according to my buddy who's also a dealer for them ... Dammit I just hate being wrong and it's definitely 760....😫😡  😜
Best of luck with you choice 👍