Throtlle goes back to flight idle on its own

[skywagon8a]

I wouldn't think that thickness would be of any concern. The leather is pliable, does not tear and provides a durable friction generating surface. What ever thickness is available and fits the location should work.

 

[musket]

Check this drawing http://www.supercubproject.com/drawings/pdfs/A3250023.pdf and then sub-drawings B-B and V-V.

 

[mike mcs repair]

I NEVER use the old leather type disc, or anything...

whats more important is how the cable end lines up with carb throttle arm, so it is "relaxed" and not in a bind trying to move the throttle arm.......

 

[don d]

There are was. Taking off in a friends piper pacer and going to demonstrate a short takeoff. Let go the throttle to grab some flaps, throttle came back. Just embarrassing.

 

[Fortysix12]

I know this is an old thread but what I have found to work very well is a split rubber grommet. I take a razor and slice a bulkhead grommetright down the middle creatring two halves , I choose the one that has the smaller holes same size as the throttle lever stud and , about 3/4 OD. Slice it down the middle and divide them on the front and rear. They seam to last a long time. Most recent build is 4 years, 700 hours.

 

[Cardiff Kook]

Would a throttle creeping forward (as opposed to backwards) be caused by the same set of issues outlined in this thread?

 

[frequent_flyer]

Would a throttle creeping forward (as opposed to backwards) be caused by the same set of issues outlined in this thread?

Isn't it standard practice to have a spring on the carb throttle arm that pulls the throttle full open if the control cable breaks? If the throttle moves forward on its own then that spring is too strong or the system total friction is too low.

 

[av8rtom]

I bought the univair washers and they weren't any better than the worn out ones..., I went to a good tackle shop that rebuilds every kind of reel imaginable and matched up some real drag washers and haven't had any problems since!

 

[aktango58]

I have had two throttle control failures, including one crossing the mountains late as it was getting dark. Those $.39 cotter pins are worth every penny.

Having the throttle go up in power is much nicer than going down when things come apart.

 

[Cardiff Kook]

Isn't it standard practice to have a spring on the carb throttle arm that pulls the throttle full open if the control cable breaks? If the throttle moves forward on its own then that spring is too strong or the system total friction is too low.

is this the case?

 

[DENNY]

Pretty sure my carb does not have a spring on the throttle. Depending on the prop it could go well past redline if it did.
DENNY

 

[frequent_flyer]

Not an expert on these carbs but this document references the throttle opening spring -

https://www.expaircraft.com/PDF/marvel-schebler-OH.pdf

and here are a couple of extracts -

 

[frequent_flyer]

This extract should remove any possible doubt as to the purpose of the spring -

 

[BC12D-4-85]

Typically they are a MA-4SPA on Lyc O-320's. See Page 1-1 for a description of the "SAFETY THROTTLE LEVER SPRING"

http://www.insightavionics.com/pdf files/MA-4 Carb Manual.pdf

Gary

 

[DENNY]

Yep, there it is for some reason I had a picture of the lien lever in my mind
DENNY

 

[Cardiff Kook]

So if my throttle is slowly pulling open this is spring is thr likely culrpit? Wonder how i could adjust tension.

I will start with friction washers.

 

[Scott A]

Check this drawing http://www.supercubproject.com/drawings/pdfs/A3250023.pdf and then sub-drawings B-B and V-V.

That drawing shows the throttle lever link rod going into the top holes and the throttle cable to the carb on the bottom hole. It seems most of the guys who work on them say the link goes on the bottom holes, throttle to carb on the top hole?

Also, my link rod has two holes on each end. I can't tell from the drawings, is the second hole for a cotter pin on the back side (so there would be a cotter pin on each side of the throttle lever through the link rod)?

 

[AKjurnees]

I had a mechanic lube the throttle lever, pissed me off. Why CC can’t make a throttle friction knob on a brand new airplane is beyond me.

 

[Steve Pierce]

They do on the new stuff but not on the Top Cub.

 

[Steve Pierce]

I had a mechanic lube the throttle lever, pissed me off. Why CC can’t make a throttle friction knob on a brand new airplane is beyond me.

I keep meaning to come up with a knob the size of that throttle lever but and drill my throttle panel for this reason.

 

[Scott A]

@Steve Pierce, I am guessing you've taken apart A LOT of original cubs and the throttle lever link rod is always on the bottom? Not the top holes as shown in the Piper Drawing four post up (or I'll try to attach an image).

 

[Steve Pierce]

I have disassembled 5 Super Cubs that had never been apart. I went through all my pictures and this is what I found. Three different airplanes ranging from 1972 to 1982.

 

[Scott A]

Thanks Steve! Bottom it is. Interesting that two have washers under the cotter pins and one does not.

 

[Dave Calkins]

For the EXP guys......

install a missile nut in place of the castle nut and cotter key. Drill a hole in the cover panel that will fit a socket that fits the castle nut....voila, an easy way to adjust the friction. PS, a knurled knob could be fabricated that allows in-flight adjustment instead of the castle nut or missile nut, but I have not found it necessary to fiddle with after doing the missile nut thing and periodically adjusting it.

I meant to write “… drill a hole in the cover that will fit a deep well socket that fits the missile nut…”

the new website will not allow me to edit my post from way back