Could someone tell me the best way to set up my throttle linkage for my LT 40. I am using an O.S. 46 AXII motor. I had it set up using one pushrod through the firewall with bends to the throttle link. This was causing a lot of binding and I didnt like the way it was.

I have seen some different set ups around using ball links and four stroke setups but still am confused and would like some suggestions as to what the best most reliable setup to use would be.<br type="_moz" />

Consider something like this...

[link=http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXFU90&P=7]Click me![/link]

yup. an alternative which you've alluded to would be a ball link...
that being said, where was the binding occuring? was the throttle pushrod set up per the plans?

http://www.sigmfg.com/BuildManuals/S...detLT40P4.html

if you remove the pushrod / linkage from the servo end, you should be able to manually move the throttle pushrod VERY easily.
if you can't, find out where the pushrod is binding and eliminate it.
it's probably obvious but I'll state it just to make sure: make the pushrod run is as straight as possible

I always use cable pushrods with ball links for the throttle. You won't have any binding and it is always smooth. I never built the LT-40, but I remember the Kadet Mark II used a cable pushrod.

The issue i had is having to make multiple bends in the rod to get it to go smoothly.   I had to make a large z bend to get it to come out of the pre drilled hole to the servo smoothly and then i had to make two more bends to get it to go over the engine mount and reach the throttle arm.  <div>
</div><div>Then when i would move the servo it was binding because the throttle arm moves in a quarter circle turn and the pushrod doesnt move at an angle.  if that makes sense to you.  Sorry im not at home to take a pic.</div>

+1 on the cable push rod......Gene

I use the flexable cable inside a plastic sleeve with screw-loc pushrod connectors at each end. VERY easy to adjust your throttle & servo this way. Tower hobbies sells them & they are sold by Great Planes. I use the brass ones and buy them in bulk for less tha $10 a dozen......Gene

Consider an alternative DCE. I am just finishing up a Sig Senior Kadet assembly this week and it is very close to your LT-40.

If you think about it the typical genaric trainer types always locate the throttle servo in a horrible location in that 'brick plate' with the other servos. Now with any two stroke engine the linkage is going to need to be on the right side and the servo is normally placed about the middle of the fuselage and the required double bends always give the fellows fits.

Here is a relitively simple, inexpensive solution that provides very free and easy throttle movement. Just forget that provided position that virtually all arfs provide and mount the servo in the forward compartment all the way on the right side simply done by just mounting a couple of sticks to your servo and cutting them off even then epoxy them to the sides while still mounted on the servo.

Now the second part of the solution is to forget the stiff and large rods that are typically provided and use music wire of a much smaller diameter. Normally at the LHS and around 30 to 40 thousanths. Use solder on thread ends and then a plastic clevis or ball cup. At the servo use an EZ Just with the set screw. this wire is quite flexible and works even better than the stranded flex wire for any kind of reasonable bend. The beauty is you seldom even need to use an outer housing which frequently causes all the bindings with bends.

This is a system I use on just about everything and it offer the smoothest and likely the most friction free operation of all.

John

The pre-drilled hole in the firewall isn't necessarily in the best location for your engine. Just drill a new one and relocate your pushrod.

Kurt

unfortunately I didnt realize this during the building phase. My model is ready to go... so im gonna have to figure it out or do some hacking... thanks for the tips guys

You are welcome DCE and thats just something to consider for the next one. Sometimes what can help when using the standard mounting of the throttle servo that may require a double bend is to try the piano wire pushrod for the throttle anyway if stock setup is to stiff. The very thin piano wire since it is still a very loose fit in the housing that is provided and it will often still work better than even the stranded flex cable.

John