ElectricMotorcycleForum.com
Makes And Models => Zero Motorcycles Forum | 2013+ => Topic started by: MajorMajor on July 17, 2016, 02:52:18 AM
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Hi everyone,
Is the ground strap on my FXS supposed to be zip tied to the chassis (see pic)?
http://i.imgur.com/aj2xwzM.jpg (http://i.imgur.com/aj2xwzM.jpg)
(http://i.imgur.com/aj2xwzM.jpg)
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I don't have an FXS so I can't tell you what it's supposed to look like but that definitely doesn't look right. In order to be effective as a ground path the strap needs a solid connection to exposed metal (no paint etc.). Back in the day when I worked at Best Buy installing stereo amps we used a star washer to dig into the metal of the frame to ensure a good ground path. It looks to me like the ring broke off the ground strap so someone just zip tied it.
Do you see a bolt with a ring where the ground strap should be connected?
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Good catch, definitely looks like the ring was broken.
I don't see where it would have been originally attached to, though.
Is the dealer the one who attaches the ground strap?
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I can't say for sure but it seems likely that it should have been connected by the factory. More than one dealer has told me that pretty much the only thing they do when the bikes arrive is remove some protective plastic from the colored portions of the bike and screw in the side mirrors....unless you order extras like top case, chain kits, power tank, charge tank etc.
Was your bike a demo?
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OMFG! mine is just like that! the ground strap is bare and is being grounded to the upper shock body. attached only by a zip-tie. granted it is a "metal to metal" contact but come on. what happens when the AZ heat dries out that zip-tie and it breaks?
i'm calling my dealer buddy and see what he has to say.
keep you posted.
laters,
laramie ;)
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granted it is a "metal to metal" contact but come on. what happens when the AZ heat dries out that zip-tie and it breaks?
Okay, I'll bite...what does happen? The upper shock body would then "float" electrically. I'm not sure this would qualify as a dangerous condition, although it's certainly better to have it reliably grounded.
I don't think that zip-tie is ever going to dry out, either...those things are really tough. It might deteriorate from UV if it was out in the sun, but this is well-protected from that, isn't it?
That's clearly a change order tag on the strap. I'd guess that this was just a stop-gap measure to ground the shock tower when they realized the mounting bolts weren't doing the job. I'd be willing to bet they've come up with a more permanent solution since then.
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Was your bike a demo?
It's supposed to be brand new (less than 50 km on the odo, can't remember exactly how low the number was).
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That's also the way it's done on my new FX. Nothing to worry about imo. There is no fuel to cause trouble with sparks. And how much of a potential would build up anyway? It's not like it's an exposed piece of the bike.
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This is very bad Earth/Ground connect. Aluminium is not bare metal but has an hard coating on aluminium oxide which stops it corrosion.
this should have a mechanical and electrical tight joint. screw and star washer. this is the international standard for earthing.
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Closer examination of the tag attached to the ground strap shows "GROUND STRAP RF RETURN SHOCK CASTING TO FRAME". I was wondering why they cared if the shock tower was grounded, but it seems they were having some sort of problem in the RF range. Either the bike was emitting too much RF radiation (maybe not actual RF, but energy in the RF band, perhaps generated by the high-frequency waveforms created by the motor controller), or perhaps RF energy was coupling in and degrading performance somehow. My best guess is the former, with the shock tower behaving as an antenna to disperse RF energy, but we do know there have been issues with the motor controller performance being somewhat susceptible to interference from outside sources.
Firepower is right that aluminum oxidizes, and quite a bit faster than steel does. The reason it's rarely an issue is that unlike iron oxide, aluminum oxide is stronger than bare aluminum, so it doesn't flake away like rust does, and it's a good electrical conductor as well. Sure, what they came up with is a kludge, but it seems to work and I wouldn't be too concerned about it. Especially if it was an "emitted RF" problem, it probably won't make a bit of difference even if it does fail. The FCC has to have some standard to enforce, but they act like the slightest spurious radiation is going to bring down the International Space Station, when in reality it rarely has any effect at all.
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Aluminum oxide is an electrically insulating material with high resistivity that increases with purity.
It is very thin and easily penetrated with a mechanical connection using star washer and screw or rivets.
a loose connection will just form new oxide when it is scratched and produce intermittent connections
there is also the problem of galvanic reaction between dissimilar metals.
http://hypertextbook.com/facts/2006/EuniceHuang.shtml (http://hypertextbook.com/facts/2006/EuniceHuang.shtml)
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My FXS is identical, but my '15 FX has no strap at all. I can't see what this would be for anyway, unless the friction of the shock builds static electricity.
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My late 2018 FX has the some sort of half-baked effort, just a bit worse. The cable is ONLY cable tied with the bolt end left unattached and no bolt. Which is to say it has never been grounded and now I've cut it free. I haven't noticed anything odd but I don't listen to the radio 8)
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Doug S. is right. :) Unlike ICE bikes, the Zero line does not use the frame as ground. That strap and nearly all the others on the bike are solely for preventing spurious RF emissions. Cutting or removing that strap would not cause the bike to do anything, except emit noise. Any piece of metal near rapidly changing electric fields can become an unintentional antenna.
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My 16FX is zip tied the same. I'm not concerned about the zip tie (they are all over the bike), and I'm not concerned about poor RF isolation of the shock. But unfortunately, it is the sort of hack that makes you wonder.
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Those RF emissions may cause something to malfunction.
Zero put that zip-tie there intentionally, for whatever reason. I'm sure they considered and rejected a harder fastening method.
I do know that RF emissions are a thorny topic for engineers. If you really want a formidable engineering topic to intimidate you, lookup "waveguide theory". (Yes, I took an RF course in the US Navy and instrument calibration sometimes involved interference checks).