Van's Air Force
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Sticky control cables
- Thread starter Reddsky1
- Start date
dpansier
Well Known Member
Cable Luber
These are widely used in the motorcycle world to lubricate control cables.
https://www.phatperformanceparts.com/ProductDetails.asp?ProductCode=1606-0002
These are widely used in the motorcycle world to lubricate control cables.
https://www.phatperformanceparts.com/ProductDetails.asp?ProductCode=1606-0002
Mike S
Senior Curmudgeon
Sticky control cables can be a symptom of bad engine ground. There are other reasons, of course, but---
The heavy current when using the starter has been known to fry the control cables------if the current cant get to ground properly.
Just to be sure, check your ground cable.
The heavy current when using the starter has been known to fry the control cables------if the current cant get to ground properly.
Just to be sure, check your ground cable.
JonJay
Well Known Member
Not sure there is any practical way.....
I did a destructive test on the Control Cables that Vans sells. The way the cable is designed and captured in the Conduit Body you can not gain access to the inner cable at all without destroying the Conduit Body.
I have emailed the manufacturer directly and will report on what they have to say about lubrication but I suspect that they are permanenltly lubricated for the life of the cable.
Double check your cables where they may be exposed to severe heat, like around the exhaust. The cables are rated for a maximum of 145 deg F. It is very easy to "cook" the cable and this has been known to cause binding.
Also, you can reduce cable friction by avoiding bends where possible. Make the cables as straight as practical.
I did a destructive test on the Control Cables that Vans sells. The way the cable is designed and captured in the Conduit Body you can not gain access to the inner cable at all without destroying the Conduit Body.
I have emailed the manufacturer directly and will report on what they have to say about lubrication but I suspect that they are permanenltly lubricated for the life of the cable.
Double check your cables where they may be exposed to severe heat, like around the exhaust. The cables are rated for a maximum of 145 deg F. It is very easy to "cook" the cable and this has been known to cause binding.
Also, you can reduce cable friction by avoiding bends where possible. Make the cables as straight as practical.
I agree with JonJay - I dissected a bad one and couldn't figure out how you'd lube it.
At 840 hours, I am on my second Throttle and Mixture cable, and have the third mixture cable standing by to go in to the game. I did a lot of research after I had the first one go bad, and came to the conclusion that FWF heat is probably the issue, and that I couldn't find a reasonably priced alternative that promised to be much better. However, hope springs eternal, and every once in awhile, I go off on an internet search for better cables....
Paul
At 840 hours, I am on my second Throttle and Mixture cable, and have the third mixture cable standing by to go in to the game. I did a lot of research after I had the first one go bad, and came to the conclusion that FWF heat is probably the issue, and that I couldn't find a reasonably priced alternative that promised to be much better. However, hope springs eternal, and every once in awhile, I go off on an internet search for better cables....
Paul
JonJay
Well Known Member
Factory Response
The cables are lubricated with a lithium grease at the factory "for the life of the cable". There is no way to add grease or service the cable. However, the control heads (knobs and mechanisms) use "O" rings that do dry out. They suggest lubricating the rods in the control heads with a lithium grease. Run them in and out a few times to re-lubricate the "O" rings and reinstall. I intend to try this soon and see if it makes mine operate better.
Any protection you can provide to limit the FWF cables from exposure to heat will extend their life.
The cables are lubricated with a lithium grease at the factory "for the life of the cable". There is no way to add grease or service the cable. However, the control heads (knobs and mechanisms) use "O" rings that do dry out. They suggest lubricating the rods in the control heads with a lithium grease. Run them in and out a few times to re-lubricate the "O" rings and reinstall. I intend to try this soon and see if it makes mine operate better.
Any protection you can provide to limit the FWF cables from exposure to heat will extend their life.
JonJay
Well Known Member
Not Sure
I know some are using it to try to protect the cables. My theory on fire sleeve is that it will get saturated with the ambient heat inside the cowling anyway and would offer little long term protection. Fire Sleeve is just insullation with a fire proof silicon jacket. Put insullation in an oven, and eventually the insullation is the same temperature as the oven.
If there was relatively cool fuel running through it, like on fuel lines, it will insulate the cool fuel from the hot air. But, the control cable is just plastic and steel. It will eventually heat to the same temp as the surrounding air.
Radiated heat is a different animal though. Heat shields will protect from the radiated heat of exhaust pipes so that is a given if cables are very close to them.
One mans opinion always subject to being changed by smarter men than me.
I know some are using it to try to protect the cables. My theory on fire sleeve is that it will get saturated with the ambient heat inside the cowling anyway and would offer little long term protection. Fire Sleeve is just insullation with a fire proof silicon jacket. Put insullation in an oven, and eventually the insullation is the same temperature as the oven.
If there was relatively cool fuel running through it, like on fuel lines, it will insulate the cool fuel from the hot air. But, the control cable is just plastic and steel. It will eventually heat to the same temp as the surrounding air.
Radiated heat is a different animal though. Heat shields will protect from the radiated heat of exhaust pipes so that is a given if cables are very close to them.
One mans opinion always subject to being changed by smarter men than me.
ronschreck
Well Known Member
Paul,
I am on my second Prop and Mixture cables. They were both Van's quadrant cables with "NOT FOR AIRCRAFT USE" printed on the cable itself. I have replaced them with aircraft cables from Aircraft Spruce. I wonder if the construction of the "aircraft" cables is significantly different. I have extensive heat shielding to protect the cables from the exhaust, and have wrapped several places with fire sleeve. If your internet search turns up the perfect cable for the job, please let me know.
I could be wrong (or my info outdated) Smoky, but I did some burrowing into the information, and discovered that the ACS cables were basically the same as the Van's cables - same company I think. So based on that, I just got the Van's ones again. I may try the ACS cables next time - I have the change procedure down to about two hours of labor...
I really think this is a general heat issue, and agree with the posts that fire sleeve probably won't help - I know as a long-time fireman that all the insulation in the world isn't going to stop you from reaching ambient temperatures eventually.....
Paul
JonJay
Well Known Member
ronschreck
Well Known Member
Paul, have you found out what material is used to coat the inside of the cables? I cut open one of the old Van's cables and it appears that something like nylon or teflon is wrapped around and bonded to the interior cable. Their catalog does not say what liner is used or what temperature limits apply. Seems to me that cable manufacturers would be required to specify the maximum temperature for cables used in aircraft. Aircraft Spruce cables have Teflon casing liner and they say this is for use in high-temperature areas such as engine compartments, but no specific temperature range is given. I'm thinking it would be interesting to put temperature indicating labels on the cables to see what we are dealing with. I know my wife can eventually destroy a teflon coated frying pan by useing too much heat. (The eggs can't stand it either...
)
Andy Hill
Well Known Member
ronschreck
Well Known Member
Andy,
I used the A-1550 cables which are the same as A-920 but with a 7/16 threaded bulhead fitting at each end. Spruce says they are for use in high-temperature areas such as engine compartments. They are not a direct replacement for Van's quadrant cables as the bulkhead fitting is placed further from the end of the cable sheath. I had to re-work my control brackets to make them fit. I can't say that the Spruce cables are better. Van's cables lasted about 500 hours. I only have a few hours on the Spruce cables. Ask me again in about two years!
Andy Hill
Well Known Member
Our throttle cable does run close to the exhaust, and now (140hrs) needs replacing. I've done some research, probably same as Paul's, so to save anyone else:
Andy & Ellie Hill
RV-8 G-HILZ
- The Van's CT Q-60 is almost certainly model number 184-VTT-2-60 from Tuthill (since that model number is on the Van's cable labels)
- The 184 is one of their better specs of this type of control to a stated Temp of 310F. See Push Pull Cable Standard - Product Data sheet
- The -2 is the "Travel" (2"). The Spruce seems to have a ~3.3" Travel.
- Spruce says their cables are "Teflon". The Tuthill / Van's ones are less specific, but have some PTFE for low friction...
- Tuthill do a similar "Aircraft cable" that is only good for ~200F - see Push Pull Cable Standard Performance - Product Data sheet that uses a "Nylon Covered Innermember"
Andy & Ellie Hill
RV-8 G-HILZ
Greg Arehart
Well Known Member
OK, more than two years gone by - how are the cables holding up?
I replaced my cables at last annual as they were getting sticky, probably from proximity to the exhaust system. Still ok this year but I got to thinking if it would worthwhile/feasible to put a "blast sleeve" around the outside of these cables to feed some cooler air to them? Probably more trouble than its worth but just wondering....
Greg
hydroguy2
Well Known Member
since I'm down awaiting exhaust repairs...
My throttle cable has a stiff spot as I reach WOT. I am wondering if this is a sign of heat damage? or just a bad spot in the cable?
How do other cables act as they get heat issues? Do they get stiff in one spot or does the friction co up and become stiff over a large range?
I'm going to the hangar today and pull one end loose to see if maybe I just have a bind as the throttle reaches full open.
My throttle cable has a stiff spot as I reach WOT. I am wondering if this is a sign of heat damage? or just a bad spot in the cable?
How do other cables act as they get heat issues? Do they get stiff in one spot or does the friction co up and become stiff over a large range?
I'm going to the hangar today and pull one end loose to see if maybe I just have a bind as the throttle reaches full open.
Noah
Well Known Member
Reviving Old Thread
REVIVING OLD THREAD.
Have a stiff throttle cable for some time now (500 hrs TT), researching control cables. Here's an interesting tidbit, Cablecraft seems to have LOWERED the temperature capability of the Vans supplied cables:
Above, Andy Hill says (6.5 yrs ago) that Series 184 (Vans standard) cable was rated at 310F. The CURRENT spec sheet says only 210F! Did they finally realize their cable was overspec'd and was not capable? Here is the current spec sheet (Andy's old link is inop):
http://www.cablecraft.com/pdfs/Push-Pull_Standard_Industrial.pdf
I am thinking of using their Blue Max cables, which are rated to 350F:
http://www.cablecraft.com/pdfs/Blue_Max.pdf
Anybody got any experience with these?? Prefer not to have to do this every 3 years. Haven't got pricing yet though.
These seem AWFULLY similar to their AIRCRAFT CABLE offering, which are undoubtedly 5-10X the cost!
http://www.cablecraft.com/pdfs/Push_Pull_Standard_Performance.pdf
REVIVING OLD THREAD.
Have a stiff throttle cable for some time now (500 hrs TT), researching control cables. Here's an interesting tidbit, Cablecraft seems to have LOWERED the temperature capability of the Vans supplied cables:
Above, Andy Hill says (6.5 yrs ago) that Series 184 (Vans standard) cable was rated at 310F. The CURRENT spec sheet says only 210F! Did they finally realize their cable was overspec'd and was not capable? Here is the current spec sheet (Andy's old link is inop):
http://www.cablecraft.com/pdfs/Push-Pull_Standard_Industrial.pdf
I am thinking of using their Blue Max cables, which are rated to 350F:
http://www.cablecraft.com/pdfs/Blue_Max.pdf
Anybody got any experience with these?? Prefer not to have to do this every 3 years. Haven't got pricing yet though.
These seem AWFULLY similar to their AIRCRAFT CABLE offering, which are undoubtedly 5-10X the cost!
http://www.cablecraft.com/pdfs/Push_Pull_Standard_Performance.pdf
Toobuilder
Well Known Member
I've been able to lube these things by disconnecting the engine end, removing the rod end, and slipping a piece of rubber/tygon hose over the end and clamping it to the outer sheath. The hose should have a foot or two of length past the end of the cable, and you fill this with gear oil. Next step is to insert the air blaster nozzle from your air compressor and pump a few PSI into the whole mess as someone works the control back and forth. Eventually, you will get a few drops of oil coming out the cockpit end and you are done.
F1Boss
Well Known Member
That's not a cable - THIS is a cable! :-0
The C45/Beech 18 has cable controls on more than a few items. Keep in mind this is 1930s technology - no PTFE or nylon...just a wire wound outer sheath covering a heavy cable. These cables are not subjest to heat (exhaust type), so that factor is not in play there.
The cables are re-lubed in much the same way Toobuilder explains. Only recently I found that the factory used a concoction that used graphite to lube these cables. This nasty stuff is used in other apps on the plane - so that no outside forces (dirt etc) can gather. My best guess on the product is a mix of graphite along with a quick evaporating carrier - like acetone - was used.
Since only NOS cables are available (but not each specific part), Beech owners figure how to lube these irrepplaceable parts. It's not fun! But at least there are a LOT of 'em!
Koolmat has some ignition wire protectors - they actually have one that has a reflective cover on their website that could help with this problem? http://www.koolmat.com/wire.shtml
I see a reflective wrap that uses a Velcro closure along the length of the tube...easy install on an existing system. And I see completed tubes that slide over the wire or cable for an initial, or replacement, installation.
I am experimenting with some of their 'zero clearance' insulation just now - initial experiments (motorcycle muffler cover) look promising. If this stuff works as claimed, it might be good for a FWF covering on our firewalls, and maybe on the inside of our cowlings. I will admit that using this stuff to cover the firewall BEFORE the engine is installed would be the proper procedure...
Carry on!
Mark
The C45/Beech 18 has cable controls on more than a few items. Keep in mind this is 1930s technology - no PTFE or nylon...just a wire wound outer sheath covering a heavy cable. These cables are not subjest to heat (exhaust type), so that factor is not in play there.
The cables are re-lubed in much the same way Toobuilder explains. Only recently I found that the factory used a concoction that used graphite to lube these cables. This nasty stuff is used in other apps on the plane - so that no outside forces (dirt etc) can gather. My best guess on the product is a mix of graphite along with a quick evaporating carrier - like acetone - was used.
Since only NOS cables are available (but not each specific part), Beech owners figure how to lube these irrepplaceable parts. It's not fun! But at least there are a LOT of 'em!
Koolmat has some ignition wire protectors - they actually have one that has a reflective cover on their website that could help with this problem? http://www.koolmat.com/wire.shtml
I see a reflective wrap that uses a Velcro closure along the length of the tube...easy install on an existing system. And I see completed tubes that slide over the wire or cable for an initial, or replacement, installation.
I am experimenting with some of their 'zero clearance' insulation just now - initial experiments (motorcycle muffler cover) look promising. If this stuff works as claimed, it might be good for a FWF covering on our firewalls, and maybe on the inside of our cowlings. I will admit that using this stuff to cover the firewall BEFORE the engine is installed would be the proper procedure...
Carry on!
Mark
McFarlane Aviation has high quality cables
I stopped by their booth at OSH They have a new throttle cable with a vernier adjustment. I was impressed with their quality. But, at this point they only list cables for the RV-10 and RV-12 in their catalogue. I am thinking about having them make custom cables for my RV-9A. I can find the lengths from Van's catalogue. If more of us request these cables I would think they would get added to their catalogue. The risk for me is that something doesn't fit properly. I need to remove the cowling and take pictures and measurements first.
I stopped by their booth at OSH They have a new throttle cable with a vernier adjustment. I was impressed with their quality. But, at this point they only list cables for the RV-10 and RV-12 in their catalogue. I am thinking about having them make custom cables for my RV-9A. I can find the lengths from Van's catalogue. If more of us request these cables I would think they would get added to their catalogue. The risk for me is that something doesn't fit properly. I need to remove the cowling and take pictures and measurements first.
ppilotmike
Well Known Member
I also stopped by the McFarlane booth and was impressed by their cable knobs, especially the vernier-type throttle body. Are their cables rated to high heats? Anybody..?
az_gila
Well Known Member
Couldn't find a rating, but they claim this on their web pages -
Special Lubrication
During assembly the McFarlane controls have a special life-time lubrication applied to critical sliding surfaces. This molybdenum disulfide and Teflon based lubricant with a synthetic grease base has been specially formulated to reduce friction and prevent galling and contamination locking of the control components from -70 F to over 1000 F.
Toobuilder
Well Known Member
That tells me that the cable may burst into flames, but at least the grease will still be good. Not much of a consolation.
rzbill
Well Known Member
Vendor Datapoint
All 3 cables (Throttle, Mix, Prop) I received from Vans approx 2010 for my 7A with -M1B were of ACS Products construction. I don't remember the ACS part numbers exactly but they were "custom" because of a "V" at the end of the part number. Upon review it appeared that the customization was inclusion of the polymer external sheath.
All 3 cables (Throttle, Mix, Prop) I received from Vans approx 2010 for my 7A with -M1B were of ACS Products construction. I don't remember the ACS part numbers exactly but they were "custom" because of a "V" at the end of the part number. Upon review it appeared that the customization was inclusion of the polymer external sheath.
cable failure
I had a prop governor cable go bad. Started getting sticky until it finally would not move. Cut it open to see what made it fail. The teflon or what ever the plastic type material is came loose at the end not near any heat but at the quadrant. It sort of raveled internally until it was jammed. I had to cut in a lot of pieces each time it was easy to move until I got to the end that was raveled. It appears to be pressed on with the crimp and thats what failed.
I had a prop governor cable go bad. Started getting sticky until it finally would not move. Cut it open to see what made it fail. The teflon or what ever the plastic type material is came loose at the end not near any heat but at the quadrant. It sort of raveled internally until it was jammed. I had to cut in a lot of pieces each time it was easy to move until I got to the end that was raveled. It appears to be pressed on with the crimp and thats what failed.
My mixture control has become very stiff until the engine warms up.
I'll be pulling the cowl soon so I can disconnect the cable end from the carb, that way I can see if it's the carb arm that's stiff or the cable. But in the meantime I was wondering if anyone knows whether this kind of thing could be something like a bad o-ring or ?? in the carb?
Because most of the posts here mention sticking in spots etc. but mine is just really stiff throughout the full range, until it warms up then it's fine.
1200 hrs on the cable and carb, btw.
I'll be pulling the cowl soon so I can disconnect the cable end from the carb, that way I can see if it's the carb arm that's stiff or the cable. But in the meantime I was wondering if anyone knows whether this kind of thing could be something like a bad o-ring or ?? in the carb?
Because most of the posts here mention sticking in spots etc. but mine is just really stiff throughout the full range, until it warms up then it's fine.
1200 hrs on the cable and carb, btw.
Far North Texan
Active Member
What did you find? Mine is exactly the same. First couple of pushes of the throttle, before engine start, is so stiff it will hardly move. Four or five pushes its moving freely and works smoothly the rest of the flight.
I'm wondering about getting a new cable or did you find an issue at the carb?
My recommendation is to replace the cables once they become hard to move. I remember reading this thread a year or so ago and thinking at some point I'll need to replace the cable, because mine were getting hard to move. A few weeks ago I went up for some pattern work and on the second time around I noticed I was faster than I expected on final, and did a low pass instead of a touch and go. On the third time around I couldn't slow the plane down and called the tower and reported I would have to do a dead stick landing. I pulled the mixture to full lean on final but the engine wouldn't stop because it still had too much fuel, so I had to turn off the ignition on short final. I crossed the numbers at about 130 knts and was lucky to have a long runway to bleed off speed, but it was a wild ride. Ironically I had ordered new cables to install "soon" and had them sitting at home. I was surprised how easily the new cables worked once I installed them. I hadn't realized how bad the old ones were. When the planes talks to you, listen.
scsmith
Well Known Member
insulating cables at hot spots
Since this tread got revived, I wanted to add something about using firesleeve insulation on throttle and mixture cables where they pass hot spots on the engine.
Ironflight and a couple of others commented earlier about the insulation slowing the heat flux but still reaching the ambient temperature eventually.
While this is certainly true of heat-soaking the entire length of the cable to the ambient temperature of the engine compartment, it is not quite right when applied to a localized region of higher temperature.
By putting insulation (fire sleeve or other) on the cable, you reduce the heat flux in. There is still axial conduction of heat along the cable from a hot area to a cooler area, and heat rejection off of the cable into that cooler area. The equilibrium temperature of the cable at the hot spot will be lower with the insulation slowing the rate of heat flux.
Absolutely the best first thing to do near hot spots is use a radiation heat shield. But in addition, it WILL help to reduce the peak temperature of the cable at the hot spot to cover that section of cable with fire sleeve. Away from the hot spot, leave the cable bare so as not to impede the heat rejection back into the engine compartment from the cable.
Since this tread got revived, I wanted to add something about using firesleeve insulation on throttle and mixture cables where they pass hot spots on the engine.
Ironflight and a couple of others commented earlier about the insulation slowing the heat flux but still reaching the ambient temperature eventually.
While this is certainly true of heat-soaking the entire length of the cable to the ambient temperature of the engine compartment, it is not quite right when applied to a localized region of higher temperature.
By putting insulation (fire sleeve or other) on the cable, you reduce the heat flux in. There is still axial conduction of heat along the cable from a hot area to a cooler area, and heat rejection off of the cable into that cooler area. The equilibrium temperature of the cable at the hot spot will be lower with the insulation slowing the rate of heat flux.
Absolutely the best first thing to do near hot spots is use a radiation heat shield. But in addition, it WILL help to reduce the peak temperature of the cable at the hot spot to cover that section of cable with fire sleeve. Away from the hot spot, leave the cable bare so as not to impede the heat rejection back into the engine compartment from the cable.
Ordered custom McFarlane replacement cables
I just removed and sent my cables to McFarlane for measurement and ordered replacement cables. I am getting the Vernier Assist on the throttle cable, and a normal Mixture cable. This is for a RV-9A with O-320 and CARB with standard Van's routing and bracket. My throttle cable tension was starting to wear in the aluminum thread area. Both old cables had rubber boots on the engine side that were cracked.
I was very impressed with the quality of the cables I saw at OSH last year. But these are more expensive cables. The throttle cable is $310 and the mixture cable is $250. I have included a link to the custom order forms.
http://1drv.ms/1Oej71W
I just removed and sent my cables to McFarlane for measurement and ordered replacement cables. I am getting the Vernier Assist on the throttle cable, and a normal Mixture cable. This is for a RV-9A with O-320 and CARB with standard Van's routing and bracket. My throttle cable tension was starting to wear in the aluminum thread area. Both old cables had rubber boots on the engine side that were cracked.
I was very impressed with the quality of the cables I saw at OSH last year. But these are more expensive cables. The throttle cable is $310 and the mixture cable is $250. I have included a link to the custom order forms.
http://1drv.ms/1Oej71W
RV8Squaz
Well Known Member
I just threw away my second set of Vans cables and will not go back. I have 1100 hours on my IO-360 RV-8 in 9 years. I had all kinds of heat deflectors and fire sleeve. I don't know what else I could have done to protect them.
I decided to do as BMW X6M above did. I spoke with Tim Paine at McFarlane and sent him my Vans cable and some measurements for overall length. Hopefully, I'll never have to replace these cables again. They are expensive (about 4 times the cost of the Vans cables), but I feel it will be worth it if I don't have to suffer through stiff cables for 2000 hours. We'll see how it goes.
Jerry Esquenazi
RV-8 N84JE
I decided to do as BMW X6M above did. I spoke with Tim Paine at McFarlane and sent him my Vans cable and some measurements for overall length. Hopefully, I'll never have to replace these cables again. They are expensive (about 4 times the cost of the Vans cables), but I feel it will be worth it if I don't have to suffer through stiff cables for 2000 hours. We'll see how it goes.
Jerry Esquenazi
RV-8 N84JE
RV-8 Throttle Cable
I removed the throttle cable on my RV-8 today. It's equipped with Titan IO-360, Bendix FI and Vetterman exhaust. Almost 700 hours TT.
The throttle quadrant was getting difficult to manipulate/actuate while the engine was cold. Once hot, not so much.
The cable crossed over two exhaust pipes on its way to the firewall. Both exhaust pipes have heat shields clamped to the pipe to shield the throttle cable from radiant heat. The throttle cable also had about 5 inches of fire sleeve over the cable in the area where it crossed the two exhaust pipes.
After removing the cable I discovered the outside green sheathing that covers the throttle cable was melted to the inside of the fire sleeve. It actually took quite a bit of force to remove the fire sleeve from the cable. I had to cut the fire sleeve length wise to get a look. The spot where it melted was directly over the area where one of the exhaust pipes crossed. The melted portion was about 2 - 1/2 inches long. The pipe closest to the FI servo was was where the melting occurred. The area where the second pipe crossed the path of the throttle cable did not exhibit any signs of melting despite the two pipes having almost identical heat shields.
I'm considering wrapping the exhaust only in the areas of where these two pipes intersect the throttle cable.
Also, if I could create a small air gap between the heat shield and the fire sleeve surrounding the throttle cable, I think that might help.
Heat rises. What if the cable was routed underneath the exhaust pipes instead of over the top? Any one ever try this?
I really like the idea of using the McFarland Aviation product.
Any one using these care to comment? Any advise/comments are appreciated.
Any
I removed the throttle cable on my RV-8 today. It's equipped with Titan IO-360, Bendix FI and Vetterman exhaust. Almost 700 hours TT.
The throttle quadrant was getting difficult to manipulate/actuate while the engine was cold. Once hot, not so much.
The cable crossed over two exhaust pipes on its way to the firewall. Both exhaust pipes have heat shields clamped to the pipe to shield the throttle cable from radiant heat. The throttle cable also had about 5 inches of fire sleeve over the cable in the area where it crossed the two exhaust pipes.
After removing the cable I discovered the outside green sheathing that covers the throttle cable was melted to the inside of the fire sleeve. It actually took quite a bit of force to remove the fire sleeve from the cable. I had to cut the fire sleeve length wise to get a look. The spot where it melted was directly over the area where one of the exhaust pipes crossed. The melted portion was about 2 - 1/2 inches long. The pipe closest to the FI servo was was where the melting occurred. The area where the second pipe crossed the path of the throttle cable did not exhibit any signs of melting despite the two pipes having almost identical heat shields.
I'm considering wrapping the exhaust only in the areas of where these two pipes intersect the throttle cable.
Also, if I could create a small air gap between the heat shield and the fire sleeve surrounding the throttle cable, I think that might help.
Heat rises. What if the cable was routed underneath the exhaust pipes instead of over the top? Any one ever try this?
I really like the idea of using the McFarland Aviation product.
Any one using these care to comment? Any advise/comments are appreciated.
Any
One alternative for throttle quadrants
might be converting control runs to use stainless steel Bowden cables. No liners to melt/jam. Bug nuts on engine end. Cable clamps on the quadrant end.
I have no idea how much more force would be required to move the controls, maybe a bit more. A somewhat more complicated build, however.
might be converting control runs to use stainless steel Bowden cables. No liners to melt/jam. Bug nuts on engine end. Cable clamps on the quadrant end.
I have no idea how much more force would be required to move the controls, maybe a bit more. A somewhat more complicated build, however.
RV8Squaz
Well Known Member
Hello Charlie,
I only have about 250 hours on the McFarlane cables since I replaced the last Vans set. The Vans lasted about 500 hours each time. I now have 1350 hours on my plane. The McFarlane cables appear to be a high quality product. However, they are 3-4 times the cost of the Vans. Even if I only got 1000 hours out of the McFarlane cables, I would still be happy since they are such a pain to replace. Good luck!
Thanks Jerry. I will give McFarlane a call next week. Did you go with a 60 inch cable? I there any chance they have your specs on file?
Thanks again!
Thanks for the suggestion Scott. I'll check them out. Are you using Bowden cables?
Thanks,
petercavallo
Well Known Member
Cause and solution for hard to move cables
Hi,
Regarding the Cables available from Vans, we found it seems they get hard to move over time (harder and harder) seems that when we cut them open the outside Teflon liner starts to fray and jams up the cable (slowly it seems so it provides lots of warning)
Best we can tell the problem is caused/exacerbated by the cable restrained too tightly the contact point of the restraint is where the cables Teflon liner seems to fray. (let us know if you found the same)
The fix (it seems for this particular problem) is to not have the cable restrained too tightly keeping the cable free to move a little
Regarding heat and other issues ......other solutions I guess
Peter
RV 6.2
Hi,
Regarding the Cables available from Vans, we found it seems they get hard to move over time (harder and harder) seems that when we cut them open the outside Teflon liner starts to fray and jams up the cable (slowly it seems so it provides lots of warning)
Best we can tell the problem is caused/exacerbated by the cable restrained too tightly the contact point of the restraint is where the cables Teflon liner seems to fray. (let us know if you found the same)
The fix (it seems for this particular problem) is to not have the cable restrained too tightly keeping the cable free to move a little
Regarding heat and other issues ......other solutions I guess
Peter
RV 6.2
