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| Mirage Drive Cables Rusting @Swaged Fittings? http://www.hobie.com/au/en/forums/viewtopic.php?f=71&t=58775 |
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| Author: | PeteCress [ Sat Aug 13, 2016 7:49 am ] |
| Post subject: | Mirage Drive Cables Rusting @Swaged Fittings? |
Since Day-1 I have been diligent about rinsing my Mirage Drive with fresh water after every use - I mean really hosing that sucker down. But yesterday, after less than a calendar year of ownership (let's say 9 month's use) one of the cables parted. https://photos.google.com/album/AF1QipM ... AzE5BU0Nkr Looking at all the cables, I see that some are totally rust-free.... virgin.... https://lh3.googleusercontent.com/Lr08N ... 7-h1008-no while others look badly rusted.... in all cases where the cable enters the swaged fitting. https://goo.gl/photos/b4jp3jus7Nnusa7M8 Could somebody with engineering expertise comment? Unencumbered by any technical knowledge, I am thinking "Defective Material" - as seemed to be the case with the downhaul cleat pop rivets (https://www.hobiecat.com/forums/viewtop ... 71&t=57285)....... or something about the swaging process... |
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| Author: | mmiller [ Mon Aug 15, 2016 4:44 pm ] |
| Post subject: | Re: Mirage Drive Cables Rusting @Swaged Fittings? |
Looks like the images are not on a public site. I can't view them. Usually rust at the swage fitting would be from a build up of debris and salts I think. No other logical explanation except maybe the cutting tool left some carbon residue. That could bleed a rust, but would not be a structural issue. |
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| Author: | PeteCress [ Mon Aug 15, 2016 5:02 pm ] |
| Post subject: | Re: Mirage Drive Cables Rusting @Swaged Fittings? |
mmiller wrote: Looks like the images are not on a public site. I can't view them. My Bad.... Google migrated all my photos from Picasa to their own UI and it looks like they did not migrate album permissions.I set the permission to "Everybody" and, hopefully, you can see the pix now. I cannot test the permission bc Google knows it's me and, of course, I have permission.... so if anybody has a problem getting to the pix now, please say something so I can take it further. A salt/crud explanation would beg the question of why some of the cables are pristine and others are so badly rusted. |
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| Author: | fusioneng [ Mon Aug 15, 2016 6:09 pm ] |
| Post subject: | Re: Mirage Drive Cables Rusting @Swaged Fittings? |
All 400 series stainless rusts on the surface, unless it has been dipped in acid to passify the metal ( look it up) but that rust is only surface rust and not structural. This is just the very small percentage of iron required to give the stainless it's strength. It's not a big concern. However those cables are under high stress and much flexing, so you can assume the cables will fail over time, there isn't much that can be done, thats just the nature of the metals. In other words your cables failing has very little to do with a tiny bit of surface rust on the surface. A 300 series stainless (with even less iron) would not be able to hold up to the stress (it's mostly nickel which is not too strong), and can't take the constant flexing and tensile load as would be required by a cable. I know a lot about that kind of stuff, it's not as much the tensile load, it's the constant bending that is killing the cables, just think of them as a consumable item on the mirage drive. 3-5 yrs of normal use, and probably under a year with heavy users, welcome to metalergy, I know of no replacement for what they have that would do better, well maybe elgiloy but that would increase the cost of the cable 10x. Knowing Hobie, they are very smart, and likely already using the finest materials available ( that's why the cables are so dang expensive, I'm pretty sure they are not making them for a buck in some chinese sweat shop, then trying to sell to you for $40, they likely cost allmost that much to make (exotic materials, custom design, etc). One thing that I do on all my stuff when new is soak everything down with clearcoat spray when new (any bare metal (ie.. All rivets, all stainless screws, etc). This seals all the stuff from wetting water seepage (water wicking into and under things), the wicking water with salt in it is the real killer, and can't really be rinsed off. This gives you a couple extra years protection from galvanic corrosion, and helps keep everything looking shiny and nice. Hope this helps FE |
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| Author: | PeteCress [ Tue Aug 16, 2016 5:40 am ] |
| Post subject: | Re: Mirage Drive Cables Rusting @Swaged Fittings? |
fusioneng wrote: ...it's the constant bending that is killing the cables, just think of them as a consumable item on the mirage drive. 3-5 yrs of normal use, and probably under a year with heavy users... First time I looked at it my kneejerk reaction was that continuing the chain all the way around seemed more durable.... as in a bicycle chain - which is also a consumable but would seem to be longer-lasting than SS cable..... Also repairable - bicycle chain-breaker tool, spare links, and so-forth.I guess they have their reasons... Less than a calendar year's use for me....and that's with sitting idle during winder months.....maximum sailing days 2x per week.... and I am not by any stretch of the imagination a "Heavy User" (75 years old, barely able to walk). Even so, it sounds to me like, when Hobie Warranty finally says "Sorry, no deal", I'm ordering four replacement chain/cables instead of just two.... |
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| Author: | fusioneng [ Tue Aug 16, 2016 5:02 pm ] |
| Post subject: | Re: Mirage Drive Cables Rusting @Swaged Fittings? |
If it's any conciliation I'm a pretty heavy user, I'm out most weekends all year around peddling usually 10-15 miles every other weekend. My cables typically last about 3 yrs, I'm fine with that, actually I go thru more fins than cables, once the fins get stretched out they flutter pretty bad at higher speeds. FE |
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| Author: | Yakass [ Tue Aug 16, 2016 10:39 pm ] |
| Post subject: | Re: Mirage Drive Cables Rusting @Swaged Fittings? |
As someone who has been working in Hobie stores for a good while, I have seen numerous instances of chains broken at the swage. In every single case I can recall rust was the cause of the breakage. Rust will always appear on the exposed cable before it appears any where else and it's pretty easy to see why when you stop to think about it. While the drive is soaking in salt water that salt water is permeating inside the cable strands. While it is true to say that the appearance of rust is generally always surface rust, it can begin to damage the cable strands from the inside if left to fester without attention for long enough. I have witnessed that many times. I have also heard a few people claim they thoroughly rinse the drive after use yet still observe surface rust form on this exposed cable. I usually respond by saying there is every chance they just aren't doing it thoroughly enough, and or lubricating it often enough. It isn't enough to just remove the salt water on the surface of the cable - it really needs a good stream of water to douse it (I use warm water for this) to make sure any salt water that bled in through the strands is getting rinsed out to. Personally I am very diligent with rinsing as well as lubrication, especially on that bit of exposed cable. I can get years out of the chains without ever seeing a single spec of surface rust whatsoever (never once had one break), and it has always been the case for me (been using Hobie's for a decade now) and for a good deal of that decade I was a very heavy user. So in conclusion - my opinion is that it just isn't getting rinsed thoroughly enough, and or not lubricated enough or with the right kind of lube. I use Inox+ or Lanox, but I'll probably be using Hobie's own lube from here on in. |
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| Author: | zarbs [ Wed Aug 17, 2016 1:39 am ] |
| Post subject: | Re: Mirage Drive Cables Rusting @Swaged Fittings? |
I give my drive a good high pressure wash down each time after use, occasionally I give the chain/cables a douse of 'Salt-Away' and lube with Inox. No problems so far but if I do I will blame this thread for jinxing me. |
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| Author: | fusioneng [ Wed Aug 17, 2016 6:32 am ] |
| Post subject: | Re: Mirage Drive Cables Rusting @Swaged Fittings? |
I've had to replace maybe a half dozen cables now, everytime they break I look them over. It's typically the same story every time. All of them so far have broke in the middle ( never near the ends). The problem appears to start with a split in the sheathing (always near the center). Think about it you have maybe 10-15 individual strands making up the cable all under near equal tension and flex exposure, with the max flex exposure point varying dependent on the strands position in the bundle. Each strand can be flexed a certain number of times until it eventually fails and breaks. Once the first strand or two break the bundle expands (splitting the sheathing). Now each of the rest of the strands in the bundle must take on a little more of the tensile load. As each of the first few strands break from flexural strain (not tensile strain), the total load is divided between less and less strands. Once you lose a certain number of strands, then tensile modulas takes over and the remaining strands break in pretty rapid succession. If you were to peel back the sheathing and inspect each strand with an electron microscope you will witness some very old breaks from flex fatigue (usually grey in appearance, and likely rusty (because of salt water wicking (well described by Josh BTW). The last few strands that broke are clearly tensile break (from there not being enough cable strands left to withstand the load). Typically the break point will occur at the weakest point on the strand which is typically the point where the most flex occurred over the strands service life. This is the way this stuff works, and why and how the cables fail. What we gleen from this is, a chain reaction occurs typically with the first few strands failing by flex fatigue. A good indicator that this chain of events has already started, is a split in the modified Poe elastomer sheathing. If your planning to cross the English channel, and the sheathing is already split, means the chain of events has already started, and your likely not going to make it across without the cable failing, eventual failure at that point is inevitable. Nobody can predict when the cables will begin to fali, thats on a molecular level. However the failure will always begin near the highest point of flex, ( somewhere near the center of the cable), if any cables fail near one of the swag fittings near then ends of the cable (where there is very little flex), that's an entirely different problem. This means the swagging operation was not done correctly and all strands are not contained equally. This is why on a suspension cable bridge each strand is adjusted individually and tightened literally with a torque wrench so each strand has equal tension. Obviously a suspension bridge is built with a much higher FOS (factor of safety). Personally I feel understanding how the stuff works, why and how things fail is kinda important, well to me anyway because this is what I do for a living (my day job). Just knowing the Engineers at Hobie, who are really good at what they do (btw). All this design engineering crap was all factored in. Keith has the best Einstein quote on his signature line, regarding this subject. Designing a mirage drive that nobody can afford (aka space shuttle), nobody would buy a $3000 dollar mirage drive. Just my two cents FE |
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| Author: | PeteCress [ Wed Aug 17, 2016 6:35 am ] |
| Post subject: | Re: Mirage Drive Cables Rusting @Swaged Fittings? |
zarbs wrote: ... and lube with Inox...... INOX MX-3, right?If so, is there a two-digit number after it? Kind of confusing to the clueless like me.... there's MX3-60, MX3-100.... and I can't figure out whether the suffix indicates packagaging or a subset of the formula. Yakass wrote: I use Inox+ or Lanox, but I'll probably be using Hobie's own lube from here on in. Looks like Lanox is INOX MX4.... What would favor Hobie's lube over INOX MX4?..... I am thinking price here.... Ridiculous prices like $15-20 bucks for a little 100-gram pressure can while INOX is available in 5-liter jugs for something like ninety bucks.... i.e. half the price per unit volume. |
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| Author: | Yakass [ Wed Aug 17, 2016 6:50 pm ] |
| Post subject: | Re: Mirage Drive Cables Rusting @Swaged Fittings? |
Quote: What would favor Hobie's lube over INOX MX4?..... I am thinking price here.... Ridiculous prices like $15-20 bucks for a little 100-gram pressure can while INOX is available in 5-liter jugs for something like ninety bucks.... i.e. half the price per unit volume. To answer your question honestly I'd have to say nothing I'm aware of makes me favor Hobie's multi-lube over Inox/Lanox, but as someone who works in a Hobie dealership that stocks all of the above, I feel obliged to test it out simply to find out if there is a difference one way or another. Either way, I've had great results with Lanox and Inox/Inox+ |
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| Author: | fusioneng [ Wed Aug 17, 2016 8:15 pm ] |
| Post subject: | Re: Mirage Drive Cables Rusting @Swaged Fittings? |
I just spray everything down with WD-40 after maybe every other outing, seems to work fine, What I like about WD 40 is it displaces moisture. FE |
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| Author: | zarbs [ Wed Aug 17, 2016 8:23 pm ] |
| Post subject: | Re: Mirage Drive Cables Rusting @Swaged Fittings? |
PeteCress wrote: zarbs wrote: ... and lube with Inox...... INOX MX-3, right?If so, is there a two-digit number after it? Kind of confusing to the clueless like me.... there's MX3-60, MX3-100.... and I can't figure out whether the suffix indicates packagaging or a subset of the formula. Yakass wrote: I use Inox+ or Lanox, but I'll probably be using Hobie's own lube from here on in. Hi PeteCress I use Inox MX3 or MX5 (Inox plus) I don't know of any number (suffix) so it may be to do with packaging. There is a MX3FG which is food grade and the MX5 plus has PTFE (what ever that is) in it that makes it extreme pressure and a friction modifier, I only use this because 'the price was right' otherwise I use MX3. You are correct MX4 is lanox (lanonlin) |
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| Author: | zarbs [ Wed Aug 17, 2016 8:28 pm ] |
| Post subject: | Re: Mirage Drive Cables Rusting @Swaged Fittings? |
fusioneng wrote: I just spray everything down with WD-40 after maybe every other outing, seems to work fine, What I like about WD 40 is it displaces moisture. FE Unfortunately WD40 is also a very good degreaser and any grease in the drive drums etc will be washed out over time and in my opinion it is not a great lubricant when compared to Inox. I have used WD40 but found it left a black 'tide mark' around the drive well after I used it which was a pain to get off my yellow yak. |
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| Author: | PeteCress [ Thu Aug 18, 2016 8:30 am ] |
| Post subject: | Re: Mirage Drive Cables Rusting @Swaged Fittings? |
Yakass wrote: I use Inox+ or Lanox, Just pulled the trigger on some Lanox.But the Lanox does not arrive for a couple of weeks and the replacement chain/cables will arrive in the next few days. What would you do? - Just rinse and wait for the Lanox to arrive - Apply something else (if so, what?) My concern would be either defeating the factory lube and/or putting something on there that the Lanox could not displace. From one of the Hobie manuals: "After using in salt water or dirty water, wash the Hobie MirageDrive with fresh water. Allow to dry, then spray metal parts with WD-40™ or equivalent. Special attention should be paid to threaded cable ends, lock nuts, chain, shafts, pedals, and adjustment pins." I guess somebody could argue that "Threaded cable ends" includes the cable where it is swaged into the end.... but, since that seems to be the #1 problem area, they could have spelled it out better. Also, I sense a conflict between WD-40 and whatever lube might be applied - with the WD-40 dissolving the lube. ?? |
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