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RV-8 throttle quadrant friction imbalance

Hangar 1271

Hangar 1271

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Hard to come up for a title for this.

However, my prop control is very easy to move and requires the singular quadrant friction lock to be very tight to prevent it advancing to fine pitch. The throttle and mixture are similar to each other but require far less friction lock to stay put. When I manage to keep the prop set, the throttle and mixture become tougher to move and make subtle adjustments difficult. Obviously, this is particularly important on takeoff and landing when you really want the most throttle control. I have considered releasing the friction lock some for those flight phases but I would rather make it right.

I spoke to a mechanic and he described a way of adding some resistance at the governor end of the cable but other options would be nice to consider.

I'm using the CT 83F DELUXE throttle quadrant on an IO-360 and the Hartzell blended airfoil prop.

Thanks for you sage advice and wisdom.
 
friction

Couple of things - when the friction lock is loose, I assume all is smooth? this is important.

Is there any chance the levers are binding somewhere?

If all this looks ok, I'd just take it apart, clean all the various layers of brass that form the friction mechanism, and reassemble with a very light oil or boelube.

Also, perhaps DJM (Dayton Murdock) has some hints - he designed them after all.
 
Everything moves smoothly. Each cable appears to operate properly.

I will inspect the throttle quadrant and lubricate a little to see if that helps. Thanks.
 
La_Rooster said:
Ron, I'm planning on using a similar setup for my prop and mixture controls on an IO-360-A1B6 for my -8. Any chance you remember the lengths of your Vernier controls? Also, did the friction control come with your single lever quadrant?
Click to expand...

Sorry, I can't recall the length of the cables. That was a 3-lever quadrant and I just moved the prop and mixture to Vernier controls and took the levers off the quadrant. The friction worked fine for the throttle control.
 
Click on the link in post 4 above. When you get there, click on Ron's post 12. 4 feet.

This is particularly a problem if you're flying formation, as one's throttle has to be loose enough to go back and forth rapidly, but you don't want your prop lever advancing to 2700 RPM's. Solution I was given by Jerry Esquinazi, was to change the prop spring inside the throttle quadrant to where the prop lever stays where you put it when the friction is off. He said one would have to play with different springs to get it right. He was correct.

Jerry, Sorry if I spelled your last name wrong.
 
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No no no

Don't just assume it 4 feet because that's what someone else used. He may have a front mounted FI or bottom mounted FI or carburetor and any of a dozen different cable mounts or even a custom made mount. Get a piece of tubing and lay it on the same path you want your cable to run and measure it.

Go to Aircraft Spruce's website and follow instructions on how to measure cables:

https://www.aircraftspruce.com/catalog/appages/acscontrols.php
 
I have this issue with the prop control creeping forward unless the friction knob is cranked down, which makes formation throttle control a problem.
After pondering ways to fix it for a few days, I emailed DJM, who promptly called me on a Sunday!
Turns out, he has a "formation" version of his quadrant with individual tension knobs for the throttle, and another for prop/mixture!

He also mentioned the prop gov spring being too strong, which makes sense.

Anyway, I promptly ordered one of the formation quadrants. Guaranteed to make my formation performance 20% better!

The formation quadrants do no show in the product page on the DJM website, but if you use the search function, you get them. Oh, and the prices are out of date.
https://www.djmmfg.com/proddetail.asp?prod=SMCT3L-Formation

I think Dayton has updated the (five year old website) pricing now, but it you ordered before the update, you will get an invoice for the difference, or the option to cancel. No whining!
 

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That formation flying option is one of the best changes i have made to my aircraft. Love the ability to independently adjust the friction on the throttle independent from mixture and rpm. Plus Dayton is first class!
 
fl-mike said:
I have this issue with the prop control creeping forward unless the friction knob is cranked down, which makes formation throttle control a problem.
After ponding ways to fix it for a few days, I emailed DJM, who promptly called me on a Sunday!
Turns out, he has a "formation" version of his quadrant with individual tension knobs for the throttle, and another for prop/mixture!

He also mentioned the prop gov spring being too strong, which makes sense.

Anyway, I promptly ordered one of the formation quadrants. Guaranteed to make my formation performance 20% better!

The formation quadrants do no show up in the product page on the DJM website, but if you use the search function, you get them. Oh, and the prices are out of date.
https://www.djmmfg.com/proddetail.asp?prod=SMCT3L-Formation

I think Dayton has updated the (five year old website) pricing now, but it you ordered before the update, you will get an invoice for the difference, or the option to cancel. No whining!Does
Click to expand...

Does anyone know if this a completely different quadrant or can an existing quadrant be modified? I already own a 3 lever.
 
Pretty significant changes to the arms, friction plates, etc., so essentially a different design.
 
I ended up replacing the governor spring on the prop governor and, with some careful friction adjustment, now works fine. The throttle isn't too stiff and the prop stays put. The mixture is a little too tight but that just makes it a problem to fine tune the mixture to 1/10 of a gallon. I can live with that.
 
Howdy David. Did you buy and replace the spring yourself or did you send in the governor to have it replaced?

If you did it yourself, where did you buy the spring?
 
The manufacturer supplied a replacement and the guy who built my engine helped me (meaning he did all the work) replace it. This is 4 years ago so I only remember the big picture rather than the fine details.
 
I loosened my friction lock and applied triflow to the brass spacers and affected levers. I also relubed the control cables and mine have been work great. Good luck!
 
On my RV-8, the problem was that the cable had become cooked. I replaced it with one from California PushPull and the excessive friction went away. Probaby not the same problem, but interesting...
 
AX-O said:
That formation flying option is one of the best changes i have made to my aircraft. Love the ability to independently adjust the friction on the throttle independent from mixture and rpm. Plus Dayton is first class!
Click to expand...
Is this formation option quadrant a "drop in" for the existing 3-lever model? That's a really nice option if its easy to replace.
 
fl-mike said:
Yes
Click to expand...
Hey @fl-mike - I'm just finally getting around to thinking about doing this. Here's a pic of my current throttle Quadrant. You mentioned that the Formation throttle quad would be a "drop in" for mine.

1758767306039.jpeg
1758767617045.jpeg

However, the "formation" throttle quadrant is rounded at the top compared to mine.
1758767394405.png

I'm not sure this would "drop in". Am I looking at the correct one from DJM.

Thanks!
 
I'm curious to know why this is called a formation throttle quadrant. Having flown formation for over 60 years I hope this doesn't mean I have been using the wrong equipment all this time!
 
ronschreck said:
I'm curious to know why this is called a formation throttle quadrant. Having flown formation for over 60 years I hope this doesn't mean I have been using the wrong equipment all this time!
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The "formation" quadrant has a separate throttle friction adjuster from the mixture/prop friction control providing better friction control.
 
Thank you. From the picture, it looks like you can adjust the friction on 2 of the 3 controls. Is that right?
 
Anybody use the Vans standard one? It seems to work perfectly. Never touch the friction knob. The blocks on top eliminate any cross coupling. The controls move independently and smoothly.
 

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Does anyone have a phone # for DJM manufacturing? I ordered their flat top formation throttle quadrant over a week ago, and have received no shipping information on it yet, but the item showed in stock when I ordered it. And my credit card shows it was charged. I can’t find any phone number anywhere on their website to talk to a live person.

Thanks for the help.
 
Notso said:
Does anyone have a phone # for DJM manufacturing? I ordered their flat top formation throttle quadrant over a week ago, and have received no shipping information on it yet, but the item showed in stock when I ordered it. And my credit card shows it was charged. I can’t find any phone number anywhere on their website to talk to a live person.

Thanks for the help.
Click to expand...
Don't sweat it, DJM is good people. Mine showed up after a week or so without any comms. But if nervous, his number is 775-sevn two one-niner476
 
Update, my DJM "Formation" throttle quadrant arrived. Beautiful piece of machining. And yes its absolutely a "drop-in" from the original. But OMG, installing it was a nightmare! Getting the clevis pins and cotter pins in was a PITA and then getting the bushings lined up for the the bottom bolts was painful - all while scrunched up underneath the instrument panel. That was pretty much a day of my life I'll never get back.

I swear, the things we do for our airplanes....
 
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