Throttle Push Rod Connection........
 

Hi Guys,

Im trying to install my engine 80FS in my World Models P-40 but seem to have a problem with the throttle pushrod........ the hole thats predrilled is way off from the engine attachment......... and would require ALOT of bending to even get it close........ i was under the assumption that the throttle conection should be as straight as possible...... but to get it straight would be hard as the fuel tank sits right in the way..............

Any Suggestions ??????????

RE: Throttle Push Rod Connection........
 

You really only have two choices: Either bend the wire, or reposition the pushrod tube

RE: Throttle Push Rod Connection........
 

Most 4-strokes give you 2 poor choices: throttle arm near the middle and needle valve on the left side (from behind the plane) or throttle arm on the left, opposite from a 2-stroke and needle valve on the right, under the muffler. Either way, I normally have to re-locate the throttle pushrod on ARFs.

RE: Throttle Push Rod Connection........
 

A simple solution that usually works is to run the pushrod out straight down the fuselage sice and let it extend forward of the engine then bend a hairpin (180 degree) curve in the pushrod and bring it back to the throttle arm on the engine. By controlling the radius of the hairpin curve, you get a straight shot to the throttle as well as a straight run from the servo to the firewall. You may have to put a guide on the rod as it extends past the engine bearers before it makes the curve back to the throttle. Using a ball joint on the throttle helps with friction free alignment.

RE: Throttle Push Rod Connection........
 

There is another option mount the servo to the engine mount useing screws or glue. I use IMP PFM to glue the servo to the engine mount and they have all worked flawlessly for hundreds of flights.

RE: Throttle Push Rod Connection........
 

Hi,

I second the mini servo inside the cowl if you have room, (you don't need much). I have this set up on two of my models and it is so easy to set up the throttle throws.

Cheers,

Colin

RE: Throttle Push Rod Connection........
 

I see nothing wrong with having more than a few bends in the wire going to the throttle. Assume we are refering to 2-56 wire. The throttle load on the wire is extremly low so unwanted bending is minimal. I use thin "bailing wire" to figure out the best route for the rod, then I bend the rod. Use a "Z" bend at the servo to keep the rod from rotating, and a nylon clevis at the throttle arm.

RE: Throttle Push Rod Connection........
 

While we're on the subject....

I want to hang a Hitec H-55 servo from the engine mount using a bracket made from aluminum.

Thunder Tigre "25", under cowl, Global T6 ARF.

Will the alum. bracket draw enough heat to loosen the adhesive, or any other problems?? I've used the "'ole throttle servo at the engine compartment" trick before, but have been able to mount to firewall.

Thanks!!

Al

RE: Throttle Push Rod Connection........
 

I like to use flexible braided cable inside a tube for the throttle. The tube can have all kinds of bend in it, but the cable will still be able to slide inside it without difficulty.

RE: Throttle Push Rod Connection........
 

Thx for the replys guys........

Richard can i ask what do u put on the end of that kinda cable ? do u solder something on to connect it to the engine ?????

Thx

RE: Throttle Push Rod Connection........
 

I use silver solder on both ends of the cable to keep it from fraying, and I use EZ connectors on the throttle arm and the servo arm. I'm about to do one, so I will post some pics.

RE: Throttle Push Rod Connection........
 

Here is a picture showing one end of a Dubro flex cable before silver solder is applied.

RE: Throttle Push Rod Connection........
 

Here is a picture showing the same end of a Dubro flex cable after silver solder is applied:

RE: Throttle Push Rod Connection........
 

Since the throttle arm is much lower than the throttle servo, here is a picture showing the angle of the flex cable:

RE: Throttle Push Rod Connection........
 

Here are two pictures showing the path of the flex cable inside the fuselage. Make sure the end of the cable at the throttle servo is at the same level as the EZ connector on the servo arm. Even though the path is not straight, the braided cable still moves freely with very little effort, just like the braided cables inside your bicycle brake lines.

RE: Throttle Push Rod Connection........
 

Thx Richard ;) its a great help thx for the details plus the pictures as they say pictures say a thousand words :D

Now i just need to go to the LHS and get this cable......... and maybe a new soldering iron as mines crap and doesnt seem to heat up........[:-]

RE: Throttle Push Rod Connection........
 

The braided cables are great. Just keep in mind that the plastic sleeves needs to be supported very close to the end with only a minimal amount of the braided wire hanging out. You can see this in Richards pics. The braided cable will flex really easy without the plastic sleeve so it needs to be supported close to the end.

RE: Throttle Push Rod Connection........
 

i just crimp the metal clevis onto the wire with a pair of pliers, then make adjustments on the other end nearest the servo. I never trust my soldering and worry that the vibration may weaken the joint, hence the crimping.