1970s Model Throttle Quadrant Issue

[AlbertF]

I have a 1974 M20F, but my post applies to any model around this time that used a throttle quadrant instead of push pull controls.  Can anyone help me with either a picture of the inside of your throttle quadrant (showing the micro-switch and lever that rest on the throttle arm) OR details on how their arm operates from working this same issue?  My issue started after my annual where my mechanic fixed our gear warning that had been disabled by a previous owner.  In reconnecting the system, we find that the warning horn comes on at about 22-21 inches manifold (thus why the previous owner disabled it).  I've attached detailed photos of the switch and arm that rest against a Cam connected to the bottom of the throttle arm.  My mechanic and I have bent, adjusted, pulled, pushed, etc, on both the Cam and switch arm and it appears to not have the correct length to keep the switch closed for as long as is needed.  The arm is released at about 22 inches, no matter where the Cam adjustment is made.  See my photos.  Can some kind person send me pictures of their switch and arm and see if mine looks different? Or, have you dealt with this issue?  Anything else I could be missing?

Edited July 24, 2020 by AlbertF
wording

[carusoam]

Albert,

Did you notice on the back side where the switch has a slot that it can be moved front to back..?

This is typical for all Mooney throttles... the switch is moved to meet requirements...

Somebody may have a pic around here for the throttle quadrant version....

Best regards,

-a-

[Hank]

There's a thread here somewhere with pictures showing a groove on the throttle cable that the switch drops into to make the horn sound. On my quadrant, I can't get the (brass) screws out of the knobs. It's allegedly accessible from underneath. The referenced thread also shows where to drill a hole for access without disassembly.

[AlbertF]

Hi Hank.  No, those posts are for the push / pull controls.  There is no slot.  It is a lever that is depressed by the throttle lever until it is pulled away from the lever with sufficient room to release the switch.  This is specific to the throttle quadrant and I’m curious how others look compared with mine.  Thank you.

[AlbertF]

Well, no takers on pictures.  Oh well.  I lengthened the lever and tucked it down under the throttle shaft Cam and it works now.   I had to pull back the cam until I heard the small click indicating the lever had released the switch.   Tightened it down at that point and now my horn comes on at 14" manifold pressure...just perfect.  Still interested in pictures if anyone is ever inside their throttle quadrant. 

[markgrue]

without seeing the whole thing it looks like the switch is upside down.  Just a guess mind you.

 

Mark

[AlbertF]

 Definitely a possibility.  If someone has a picture of a working one, that should be readily apparent!  Thanks!

[EricJ]

12 hours ago, AlbertF said:

 Definitely a possibility.  If someone has a picture of a working one, that should be readily apparent!  Thanks!

Does the IPC not show how it should be oriented?   On a J model it's drawing 76-00-00, but I think it's a bit different than an F.

[AlbertF]

I’m not familiar with the IPC, but I don’t think orientation is the issue.  The switch works perfectly, it just comes on way too early.  If it was reversed, full throttle would keep the switch disengaged which would keep the horn ON.  The lever appears too short to keep pressure from the throttle engaged long enough to bring the throttle to say 14 inches. I got it to work by extending the lever with a weld, but I don’t think that should be the fix.  Thanks though!