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Replacing original throttle, mixture, and prop cables

salty

By salty
in Vintage Mooneys (pre-J models)

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salty Proficient

salty

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I'm in the middle of an engine overhaul, and my mechanic says that I should be replacing these cables. 

They appear to be the original controls. The mixture is a tiny knob that is difficult to adjust finely. I'm ok with the throttle and the prop controls, but I'd really like to get a Vernier style mixture cable, and as my mechanic says apparently it's supposed to be done at overhaul time.

But when I looked at the situation I do not see any way a human could replace these cables without disassembling the radio stack, putting the plane on jacks and removing the j-bar socket. That's not even mentioning the crazy mess with the gear alarm switch that's attached to the throttle control...

Am I missing something? Making too big a deal of this? My mechanic has never done it on an older mooney, but he hasn't come over to look at it yet, but as I said, I don't see how it's possible.

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Bob_Belville Grand Master

Bob_Belville

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I replace all 3 engine controls a couple of years ago. Not a lot of fun for a full figured old man under the panel but not that high on the DIY difficulty scale. As I recall I did have to make the throttle hole larger for the new shank. McFarlane makes the cables as "owner produced parts". 

call McFarlane's Kelli Bishop at 866-920-2741 ext. 313

https://www.mcfarlaneaviation.com/section/services/custom-engine-controls/

throttle (friction lock): https://www.mcfarlaneaviation.com/media/documents/throttle-control-form.pdf

prop or mixture (verier): https://www.mcfarlaneaviation.com/media/documents/vernier-control-form.pdf

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salty Proficient

salty

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3 minutes ago, Bob_Belville said:

I replace all 3 engine controls a couple of years ago. Not a lot of fun for a full figured old man under the panel but not that high on the DIY difficulty scale. As I recall I did have to make the throttle hole larger for the new shank. McFarlane makes the cables as "owner produced parts". 

call McFarlane's Kelli Bishop at 866-920-2741 ext. 313

https://www.mcfarlaneaviation.com/section/services/custom-engine-controls/

throttle (friction lock): https://www.mcfarlaneaviation.com/media/documents/throttle-control-form.pdf

prop or mixture (verier): https://www.mcfarlaneaviation.com/media/documents/vernier-control-form.pdf

You've got a Johnson bar? That seems to be the main issue to me. Did you do it without removing the locking block for the bar?

 

I've already talked to McFarlane, but thanks for the info anyway.

Edited by salty
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Bob_Belville Grand Master

Bob_Belville

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1 minute ago, salty said:

You've got a Johnson bar? That seems to be the main issue to me. Did you do it without removing the locking block for the bar?

 

I've already talked to McFarlane, but thanks for the info anyway.

Yes, my '66E has a JBar, plus a ram air you do not have with your C. 

No, I did not have to remove the locking block. However, if yours is original you might want to replace it as well. LASAR makes them and I made that change as well. Low difficulty but you do need to jack up the plane. 

Pics are of old locking block and new controls but before block was change.

IMG_20170120_124036731.jpg

IMG_20170120_124046833.jpg

IMG_20151127_171053181.jpg

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C-GHIJ Collaborator

C-GHIJ

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1 minute ago, salty said:

Did you do it through the bottom, or through that giant GTN-750 sized hole above them?

I did mine with everything still in the panel.  Having fingers like ET helps, but it really wasn't all that hard.  The hardest part was putting the micro switch back on the throttle cable.

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KSMooniac Grand Master

KSMooniac

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Props to you guys. I can't even imagine how you'd get a wrench within 3" of the secure nuts on the back.
McFarlane makes a socket wrench for the nut on the back of the cables. I got by without it on my J, but I might have morr room than the pre-J/Johnson bar planes.

Sent from my LG-US996 using Tapatalk

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cctsurf Proficient

cctsurf

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I did the throttle cable last year on my johnson bar C model.  It was original and the sliding sheath broke between the mount and the carburetor.  If yours are truly original, I can't urge you to replace them hard enough.

I was quite thankful for the easily removed radio right above the cables.  I worked through there and some from underneath.  I didn't find it to be too difficult.  Much less difficult than a number of other projects I've had to do on airplanes.  I had more difficulty running the cable on the forward side of the firewall than I had behind the panel.  Do it now while you have your engine out. 

Are you cleaning, inspecting and painting your motor mount?  I'd suggest doing that as well while the engine is off.  There are SO many things you have access to now that you won't have until the next time you remove your engine...which I hope is a VERY long time.  I wish those things had been done on mine when the engine was off.

 

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MB65E Grand Master

MB65E

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I would replace them!! With the engine off you'll have the time to do it right. One at a time and take your time. They are a pain in the rear but it beats the alternative. 

The throttle cable takes a pounding. The gear switch makes it more challenging but it's not the worst.

-Matt

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carusoam Grand Master

carusoam

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+1 change them if they are as old as the engine OH...

+2 really change them if they came with the plane...

Give the old ones a good look yourself to see if there is any damaged or worn parts...

PP thoughts only, not a mechanic.  There have been a few cable failures on MS both throttle and prop. Some came apart at the engine end, others at the knob end.  And one had the button fall of a knob making it a problem to activate...

Best regards,

-a-

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salty Proficient

salty

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So, I have shiny new cables now. It was a giant pain in the ass to get the old ones out (I had to remove half the radio stack and invent a tool or two to get on the nut in the back), especially the throttle, but it's done and well worth it. The old cables were in fair condition considering they were in fact original to the plane, but they definitely needed to be replaced.

Edited by salty
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carusoam Grand Master

carusoam

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Salty,

did you go with the standard T,M,P order?

Add any extra vernier type attributes?

iirc, my old 65C had its knobs in an odd order.... T,P,M? And not much vernier control....

I expect you will find some nicer smoother operation with the new hardware.

Best regards,

-a-

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carusoam Grand Master

carusoam

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Just now, salty said:

I debated that quite a bit, but settled on "fixing" it from the original TMP to the standard TPM. I'm thinking you said it backward in both places though. Otherwise, I'm very confused.

Signs that it may be...

Better to get it right from the beginning, or spend a lifetime being confused about the order later :).

Its a good thing for me to have the different shaped, colored, feel for the knobs.

Thanks for the kind response.

Best regards,

-a-

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Yetti Grand Master

Yetti

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Did we ever settle if the throttle quadrant cables need to replaced on time rather than condition?   Seems like they knob one fail on the crimp point from the rod to flexible part.   I would think the quadrant is all flexible and would go with condition unless molested in some way.  TPM is the quadrant way.

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salty Proficient

salty

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1 hour ago, Yetti said:

Did we ever settle if the throttle quadrant cables need to replaced on time rather than condition?   Seems like they knob one fail on the crimp point from the rod to flexible part.   I would think the quadrant is all flexible and would go with condition unless molested in some way.  TPM is the quadrant way.

A lycoming mandatory SB states TBO on control cables is same as engine. I don’t see why that would be different with a quadrant the cables aren’t wearing at the panel, but where they snake around and especially outside the firewall. 

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