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View Poll Results: Have you replaced one or more of your RV8 engine control cables?
Yes, at under 500 hours. 10 30.30%
Yes, at under 800 hours. 8 24.24%
Yes, at under 1100 hours. 1 3.03%
I have never replaced my RV8 engine control cables 14 42.42%
Voters: 33. You may not vote on this poll

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  #1  
Old 04-04-2019, 08:36 PM
edneff's Avatar
edneff edneff is offline
 
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Location: Oakland, CA
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Default RV-8 Engine Control Cables freezing up

My mixture control has gotten to the point where I can barely get it to the ICO position without using two hands. RV-8, IO-360

There are a number of threads on this particular topic, but most of them are fairly old. I thought it was time to refresh the topic. It seems that the consensus of opinion on this is that the Vans Cables supplied with the kit are not designed for high heat environments. (best I can tell is that I Have a Vans CT Q-55 on my 850 hour airplane)

So, a poll, and two questions:

1.) has anyone found a cable that does not have the same issues as the green Vans cables? specifics and sources would be appreciated.

2.) Since I did not build this plane, do you have any tips on approaching the replacement of the cable? It looks like a lot of disassembly will be required.

Thanks
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  #2  
Old 04-04-2019, 08:50 PM
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Only 125 hrs on mine so time will tell. I did put firesleeve and heat reflective aluminum tape around the throttle cable where it went under the engine. Nothing on the mixture cable though
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Last edited by Champ : 04-04-2019 at 08:53 PM. Reason: Oops.
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  #3  
Old 04-05-2019, 01:21 AM
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rv8ch rv8ch is offline
 
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Default McFarlane

I needed slightly different length cables due to a slightly different engine and throttle body so I ordered some from McFarlane Aviation.

https://www.mcfarlaneaviation.com/se...gine-controls/

They seem to be good quality, but since I'm not flying I can't tell you how many hours they will last.

Replacing your cables will probably not be that easy, probably a good 4-8 hours of work, plus once you get them out, you'll need to measure them carefully, order new cables, wait a week or so, then reinstall. I recommend you take care with the measurements - I didn't, and got to buy a second set.
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  #4  
Old 04-05-2019, 07:15 AM
BillL BillL is offline
 
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Ed, Ron Schreck had the same issue on is 8 and replace a cable 3+ times due to heat. He added fire sleeve and a 3/8" cooling tube to provide some air down inside the fire sleeve. I thought it was a really clever solution. The post was a year or two ago.

I think it was a different cable but the solution would work too. On my 7 I have a 4-into-1exhaust and my throttle runs parallel to it. I added fire sleeve and measured the internal temperature, it was well below McFarlane's usage limit.

Edit: added link to Rons post - funny - it was in a 2013 thread!! Time flies in the RV world.
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Last edited by BillL : 04-05-2019 at 07:24 AM.
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Old 04-05-2019, 07:50 AM
brad walton brad walton is offline
 
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I just replaced my mixture cable about 10 hours ago and 425 hours total. I spoke with the manufacturer of the cables Vans sells and they have improved the heat range since I purchased the original about 15 years ago.
I cut the old one up and the internal sheath seemed to have become soft and then began to roll up.
I had reflective sheathing over the portion of the cable nearest the exhaust, but no protection on thethreaded steel end. My guess is the steel end conducted heat to the intenal sheathing and caused it to bunch up
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  #6  
Old 04-05-2019, 12:45 PM
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edneff edneff is offline
 
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Thanks for all of the responses. As "rv8ch" confirms, this is a big job I am not looking forward to since I don't have the builder knowledge lots of you have.

I am going to get a quote from McFarlane. They asked me, "Will the clamp sleeves need to be threaded?" and I am not sure what they are referring to. Anybody know?

Quote:
Originally Posted by brad walton View Post
I spoke with the manufacturer of the cables Vans sells and they have improved the heat range since I purchased the original about 15 years ago.
Thanks Brad. It would seem from my survey that about half of the poll respondents had never replaced their cables... Perhaps they are using the newer more heat resistant product. Any idea when the product was improved, and what the new temp range is? Did you use the Van's cables for the replacement?
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Last edited by edneff : 04-05-2019 at 12:49 PM.
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  #7  
Old 04-05-2019, 01:49 PM
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Ironflight Ironflight is offline
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Ed - just a recommendation based on my own experience - they get really bad quick - if it’s taking two hands to get it “off”, then ground the airplane now until the cable is fixed - you might only have one operation left.

Paul
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  #8  
Old 04-05-2019, 01:58 PM
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Ed, these cables were new circa 2006. At 850 hours they are still hanging in there, right above a 4-into-1 pipe.

They're wrapped in fiberfrax, then aluminum foil tape, then the side facing the pipes got a formed aluminum tray. Double reflector over an insulator.

I seem to recall the mixture cable becoming a bit rachety very early on, then it smoothed out again.



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Last edited by DanH : 04-05-2019 at 02:03 PM.
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  #9  
Old 04-05-2019, 04:31 PM
Captain Mike Captain Mike is offline
 
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Ed,
I replaced cables on previous RV8, not yours, used standard vans cables but covered them with fire sleeve and heat shield. Was surprised when I removed the cables that they would not slide by hand. I recommend you get new vans cables and follow Dans and my advice to protect them from heat.

All the installation on your aircraft is per Vans instructions so will require some getting down under to disconnect and reconnect new but it is doable.

I posted a safety issue about this years ago. All cables should be protected from heat as much as possible.

Captain Mike
Building number 5 in Alabama
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  #10  
Old 04-05-2019, 04:48 PM
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Ed_Wischmeyer Ed_Wischmeyer is offline
 
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Thereís a company in California that sells better cables. Iíll have to dig to find it, but forget the vanís cables. Working great on my -8.

Ed
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