RV-8 throttle quadrant friction imbalance

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.

Governor spring

Read post number 28 in this thread.

http://www.vansairforce.com/community/showthread.php?t=95773

Thanks. Sounds pretty similar. Seems like a possible answer.

tturner said:

Read post number 28 in this thread.

http://www.vansairforce.com/community/showthread.php?t=95773

Click to expand...

Yeah, and look at post 25 in that thread. It solved the problem for me and for others who did the same. With enough friction to make the prop control feel right, the throttle and mixture move easily.

Ed Holyoke

Thanks for the advice. At least I know I'm not the only one with the problem.

Problem Solved

ronschreck said:

Click to expand...

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?

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, read Ron Schreck's post 12. 4 feet.

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.

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 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!

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!