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Mixture control cable

Mark Cigal

Active Member
Sponsor
I have an RV8 with an IO360-A1B6, 200 HP engine. I completed the build in 2004. Since then, I have had to replace the mixture cable twice due to binding. I have used cables supplied by Van's, but am wondering if there is another supplier out there. Van's recommends the 55" cable, but I think this is too long. What length has worked for you other 8 drivers ?
 
RV8 mixture cable

McFarlane has nothing for an RV 8 and they want $450+ to custom make one !!! :eek: Any other suggestions ??????
 
Try running any cable (or wire) that is under the engine through a length of Fire Sleeve. It will help mitigate the radiant heat damaging the cable.

Carl
 
I built mine with all McFarlane cables. 700+ hours and same as new. All custom lengths. Happy I did.
 
Mixture Cable

Many thanks for the input. Since I have already replaced the mixture cable twice and the prop cable once with Van's offerings, I'm going to bite the bullet and go with the McFarlane cable this time.
Jerry...... do you still have the McFarlane build sheet for your mixture cable ? I am curious to see how the measurements compare to what I'm getting.
 
After 6 years of use and 475 hours on my Vans supplied Cablecraft mixture cable it has gotten stiff and harder to operate despite the fact that I had fire sleeve on it. Fire sleeved throttle cable within a few inches of the mixture cable has no issues; go figure. When I got the quote for a replacement from McFarlane I thought there must be a typo. $475 for a 60" cable, no typo. I bit the bullet and ordered it so I'll install it at this year's condition inspection while the prop is getting overhauled at Hartzell. The way I look at it is that if I only have to replace it once, it'll be worth it. BTW, Kelli at McFarlane was great to work with.
 
Many thanks for the input. Since I have already replaced the mixture cable twice and the prop cable once with Van's offerings, I'm going to bite the bullet and go with the McFarlane cable this time.
Jerry...... do you still have the McFarlane build sheet for your mixture cable ? I am curious to see how the measurements compare to what I'm getting.

Hello Mark,

See attached picture. I don't remember which one is which. If I had to guess, I would say the 60" is the throttle, 53" mixture, and 50" prop. Having at least 2 1/4" travel is critical. BTW, I paid $225 each only four years ago. I can't believe they've gone up that much!
 

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Mixture Cable

Jerry, many thanks for the reply. Your numbers are very close to mine and I believe your assumptions as to position are correct. The cost for my mixture cable is $475 !!! It's an awful high price to pay, but if I don't have to replace it again it will be worth it.
 
Hello Mark,

See attached picture. I don't remember which one is which. If I had to guess, I would say the 60" is the throttle, 53" mixture, and 50" prop. Having at least 2 1/4" travel is critical. BTW, I paid $225 each only four years ago. I can't believe they've gone up that much!

I found 2.25" travel for the Van's cables isn't quite enough for the mixture cable. Doesn't quite bottom out at full rich if set up to bottom out at full lean. We tried everything including moving the mixture lever attachment point up by about 0.5". Cable travel should be long enough so it only bottoms out at either the control lever or controlled element, but not within the cable itself.
 
I found 2.25" travel for the Van's cables isn't quite enough for the mixture cable. Doesn't quite bottom out at full rich if set up to bottom out at full lean. We tried everything including moving the mixture lever attachment point up by about 0.5". Cable travel should be long enough so it only bottoms out at either the control lever or controlled element, but not within the cable itself.

I have the same problem. Not sure how to fix it. If the throttle quadrant allowed more throw it would be fixed.

I've wondered if somehow some movement is taken up by cable flex or some other mechanism.

Right now I have it set for full power.
 
Mark,

Heat is a huge enemy to cables. It's often overlooked due to the mindset that it is designed to be FWF.
As mentioned previously fire sleeve is very helpful. Also, the strap on heat shields.
 
McFarlane VAF Advertiser, Standard Cables

I looked at McFarlane’s site, filtered products by Vans and only found RV-10 and RV-12 as standard cables offered off the shelf. Would they consider expanding their line to the rest of the popular models? New build RV-8A and I’m interested in Prop, Mixture, Throttle cables at in stock vs custom prices.
 
The mixture cable supplied in the Vans firewall forward kit is on the longer side but I was able to fit it. I had to take up some of the slack so it can fit into the mounting plate that was bolted to the oil pan. The throttle cable is spot on. The mixture control travel seems to okay, at least when I was checking with the AvStar fuel servo, its control arm was able to travel from stop-to-stop.
 
Jerry, many thanks for the reply. Your numbers are very close to mine and I believe your assumptions as to position are correct. The cost for my mixture cable is $475 !!! It's an awful high price to pay, but if I don't have to replace it again it will be worth it.

You’re welcome Mark. I hope it works out.

At the time, McFarlanes cables were triple the cost of the Vans cables. I figured even if they only last twice as long it would be worth it. So far so good.
 
One hint for custom cables - I recommend that you measure thrice - cut once. I ended up buying two sets for the mixture and throttle due to not having fully engineered the brackets on the engine side. After getting the cables, and building the version 1.0 of the brackets, I realized I needed to do it differently and got to order the expensive cables again. Ouch.
 
That's great advice. I measured and measured until I got repeatable results. Then I made a mock up. The new custom cable will be covered with fire sleeve and will have very few bends in it (the Van's cable was too long).
Many thanks to all who participated in this thread. I've used all the great advice given and am hoping this is the LAST time I have to replace this cable :rolleyes:
 
I have the same problem. Not sure how to fix it. If the throttle quadrant allowed more throw it would be fixed.

I've wondered if somehow some movement is taken up by cable flex or some other mechanism.

Right now I have it set for full power.

That’s my thinking too…bends in the cable consuming some of the total travel. My A&P drilled a new cable attachment point on the mixture quadrant lever but it didn’t help, suggesting there bottleneck is the cable travel itself. The quadrant lever was not at full travel when it reached full available travel.

I’ve installed the larger M-S carb for my O-360-A1A, so am not sweating it if the mixture lever does reach full travel by .020-.030”.
 
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Mark,

Heat is a huge enemy to cables. It's often overlooked due to the mindset that it is designed to be FWF.
As mentioned previously fire sleeve is very helpful. Also, the strap on heat shields.

Today I took the opportunity to replace the Vans supplied Cablecraft mixture cable with a McFarlane custom cable. Time consuming but overall not a hard job. I flew the airplane last week before starting the annual condition inspection and the mixture cable was still sticking some but got better as it heated up. When I removed it today, I was surprised the firesleeve would not slide off easily. I ended up cutting it off and found that the plastic coating on the cable had melted about 12" inside the firesleeve. I checked for movement of the cable and it was completely frozen in place. I cut the cable in the center of the melted section of plastic and found that a piece of the inner sleeve closest to the fuel control unit came out with the cable. but it would still slide over the metal cable. The other half of the cable was still frozen in place. My Cablecraft throttle cable in the same general area with the same exhaust pipe clearances has no issues whatsoever. Like Bruce said, heat is the enemy of these cables. Here's hoping that the McFarlane cable lasts longer than 6 years.
 

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Alternative

Has anyone found an alternative push/pull cable? I have looked but get stuck finding a cable with a temp rating that is as high as the McFarlane.
 
I looked at cablecraft. Temp range is -65 to +350F. McFarlane is -65 to 450F. The higher temp tolerance seems to be the reason the McFarlane is lasting longer. Any other options out there with 450F or greater temp tolerance?
 
I used some old RG-59 CATV coax to simulate the cables for determining length. Allowed a similar bend radius, etc. Worked for me.

Put firesleeve on all the cables FWF, and wrapped the firesleeve in metal tape for radiant heat. Also made some custom heatshields. Fingers crossed!
 
I used some old RG-59 CATV coax to simulate the cables for determining length. Allowed a similar bend radius, etc. Worked for me.

Put firesleeve on all the cables FWF, and wrapped the firesleeve in metal tape for radiant heat. Also made some custom heatshields. Fingers crossed!

Excellent idea with the old coax, considering the cost of the good cables.
 
Mixture cable -RV8 - IO360

I have an RV8 with an IO360-A1B6, 200 HP engine. I completed the build in 2004. Since then, I have had to replace the mixture cable twice due to binding. I have used cables supplied by Van's, but am wondering if there is another supplier out there. Van's recommends the 55" cable, but I think this is too long. What length has worked for you other 8 drivers ?

Mark,

I'm driving an RV8 w/IO360 and the mixture cable is practically frozen up 600 hrs.

Vans Store lists a Mixture/Throttle cable part number CT Q-52.5 for RV10 which should be 2.5 inches shorter. Do you think that would work for me?
 
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