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 Post subject: Mirage Drive sprockets
PostPosted: Mon Jan 18, 2010 4:05 pm 
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Location: Australia
Ive shredded the sprocket twice in the last 12 months. The teeth on the sprocket get progressively sheared off. You first notice this change on the kayak(a.i) as a push of the foot slides forward way to easy. The fins end up pointing in all directions, and it maybe difficult to remove them from the slot. The sprocket is a plastic cog, and the chain is stainless steel. Why not cast an alloy cog? Kinda make sense...yes?


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PostPosted: Mon Jan 18, 2010 4:14 pm 
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Not a consistant story we have been hearing. Do you have a lot of small pebbles on the beach? Maybe the chains real tight?

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PostPosted: Mon Jan 18, 2010 5:19 pm 
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Joined: Tue Dec 01, 2009 4:30 am
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Location: AUS: Sydney midweek - Murrumbateman weekends
I had a similar problem:
Quote:
Quote:
To speed up my return I was peddling hard and pointing as high as I could without luffing the sail - then Mirage drive problems. The drive felt like it was skipping teeth. I took it out to inspect, but the chain tension felt OK. The skipping worsened soon at a point where the drive was virtually useless.


On close inspection of my Mirage drive under lights I discovered the root cause of my problem:
Image Image Image


The drive was second hand and I don't know the history. I suspect that it might have been exposed to sand which has abraded the sides of the teeth, finally wearing through and sheering the teeth off.

I found grit in the chain of the front drive on my Oasis which could well result in such abrasion. My lesson is to inspect and thoroughly clean the chain and sprockets after each trip involving a beaching.


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PostPosted: Tue Jan 19, 2010 9:11 pm 
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Location: Phuket, Thailand
okz00k wrote:
I had a similar problem:
Quote:
Quote:
To speed up my return I was peddling hard and pointing as high as I could without luffing the sail - then Mirage drive problems. The drive felt like it was skipping teeth. I took it out to inspect, but the chain tension felt OK. The skipping worsened soon at a point where the drive was virtually useless.


The drive was second hand and I don't know the history. I suspect that it might have been exposed to sand which has abraded the sides of the teeth, finally wearing through and sheering the teeth off.

I found grit in the chain of the front drive on my Oasis which could well result in such abrasion. My lesson is to inspect and thoroughly clean the chain and sprockets after each trip involving a beaching.


I have seen some photos of boats beached with the mirage drive still locked in place and the fins up against the hull, it always seemed to me to be a bad thing to do for the very reason you mentioned....sand getting into the drive chains.


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PostPosted: Tue Jan 19, 2010 10:37 pm 
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Joined: Mon May 04, 2009 5:02 am
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Location: Sydney - Parramatta
Must say I'm in the remove drive before beaching group.
The drive gets a good fresh water flush and squirt of Lanox once dry. Good opportunity to check for damage etc.

Gets transported in a heavy duty cardboard sleeve now to stop any damage to the fins.

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PostPosted: Tue Jan 19, 2010 11:57 pm 
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Posts: 2379
Location: Escondido
matcoburn wrote:
The sprocket is a plastic cog, and the chain is stainless steel. Why not cast an alloy cog? Kinda make sense...yes?
Hobie used stainless sprockets for years.
Image
They have some good points, but some serious flaws as well. The current sprockets engage the chains better and are not prone to skipping out if proper adjustment is neglected.

This damage is consistent with an incorrectly mounted chain rather than normal wear. In this next picture, one of these sprockets has over 800 logged (pedaled) miles and the other is new? Any guesses which is which?
Image
I can only tell by looking because the used sprocket (left) still has the sprocket guard attached. This glass filled nylon is pretty tough stuff.

So how can the chain be installed incorrectly? the next pic shows a chain seemingly installed correctly (sorry about the bad flash angle).
Image

But if you look from the other side, it's a half link off -- not that easy to spot for the casual observer. This will rip up the cogs
Image

The chain must be pressed into the master (extra wide) cog FIRST, before any other links are applied. It is not easy to press in all the way (when new) and can not be done correctly at any other time. When properly installed, it stays in place, even if inverted as in the case with this well used chain chain and sprocket:
Image
Subsequently the other links should be pressed in individually and inspected for any gaps or high riding tendencies before adjusting cable tension.

Needless to say, the chain/cable should be properly adjusted -- not so much for sprocket wear, but excess (power robbing) friction on one extreme, and drive slack on the other.

This does not preclude other possible causes for sprocket damage. Nevertheless, this would be my best guess by far. 8)

PS If you still want stainless sprockets, I believe Hobie still has some available. You'll also need to order bushings different sprocket guards and clew outhauls (as the top picture shows). I have both types and consider the current Nylon sprockets to be superior.


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PostPosted: Thu Jan 21, 2010 3:15 pm 
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Location: Australia
Thanx Roadrunner and Matt M. Ive bought a replacement cog and followed instructions on this forum and installed it. It has been the thicker central tooth that has broken on my old one, and one of the adjacent tooth as well. Matt, each time this has happened ive been way offshore with the wind behind the A.I with 5m sail fully out. Nowhere near sand. Ive been travelling around 10km/hr and catching swells. I think that when there is speed in the yak caused by the sail(and on a wave), if you engage the mirage drive , and lack of resistance makes it easy for the system to slip. After you catch a wave, to maintain the momentum i think that the natural response is to engage the miragedrive vigorously. It is these conditions i ve stuffed the teeth. Perhaps the tension on the chain was not optimal. Roadrunner, Id no idea that the older models had steel teeth. The more i fiddle with the mirage drive the more my confidence has returned. The idea of being stuck at sea with a disfunctional drive has been a confidence killer. Roadrunner, Ive stuck your piece into a word doco and printed it off. I will absorb all imformation. thanx.


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PostPosted: Thu Jan 21, 2010 3:18 pm 
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Location: Australia
Thanx old salt. excellent pics


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PostPosted: Fri Jan 22, 2010 4:23 am 
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Location: Phuket, Thailand
matcoburn wrote:
each time this has happened ive been way offshore with the wind behind the A.I with 5m sail fully out. Nowhere near sand. thanx.

Hi Matcoburn,
OUCH :shock: .....Not much fun being way offshore in an offshore wind and having a drive breakdown...imagine having the wind die on you out there and, in full AI mode, trying to paddle home...at least it sounds as if you were able to tack back in under sail. A spare drive would cost you a lot of money but it would be kind of nice to know you had it with you....if, in the above kind of conditions, you venture way out to sea.


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PostPosted: Sat Jan 23, 2010 1:45 am 
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Joined: Thu Aug 16, 2007 2:25 pm
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Location: Central Coast NSW Australia
matcoburn wrote:
The more i fiddle with the mirage drive the more my confidence has returned. The idea of being stuck at sea with a disfunctional drive has been a confidence killer.


matcoburn,
Philip1el's spare drive suggestion is a good one. I usually carry one when I venture offshore. If that isn't possible I would make sure to have some spare parts with me. In the 3 years I have been using the Miragedrive I have broken a few V1 masts (using Turbo's), two drive chains (V1 and V2) and one idler cable (V1).
The V2 sprockets seem to have eliminated, pretty much, the mast problem but idler cable and drivechain breakages, though rare, can happen. I always carry one spare of each.
I see you have already found Roadrunner's excellent repair tips in the FAQ's. Together they make a great workshop manual.8)
I recently replaced a V2 drivechain in the field without problem, remembering some of RR's tips. :)
His photo above with the middle of the chain clearly marked is a great tip that makes replacement a lot simpler!
This post too should be required reading:
viewtopic.php?f=11&t=8240&p=40489#p40489


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PostPosted: Tue Mar 23, 2010 9:29 pm 
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Joined: Sat Sep 20, 2008 8:19 am
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Location: Australia
Quote:
I have seen some photos of boats beached with the mirage drive still locked in place and the fins up against the hull, it always seemed to me to be a bad thing to do for the very reason you mentioned....sand getting into the drive chains.


Not a problem if you hose it all out, which isn't hard to do. My experience is much the same as Road Runners. I have a drive thats done over 8000km, but you would never guess by looking at it. Its scratched, lost some paint, but otherwise its never missed a beat... and it has been beached numerous times (I do avoid it if I can though). The key is rinsing the things out properly, and maintaining them properly.

In my experience, chains can slip and grind off sprocket teeth if the chain is too tight. Have seen it happen to customers several times now, almost always in the surf. Why surf? Because its in surf users sometimes have to pedal like mad, and if its loose, that can make it pop off. Moral of the story - don't let your chains get too loose.

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PostPosted: Thu Mar 25, 2010 12:23 am 
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Joined: Sat Apr 28, 2007 11:59 pm
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Location: Coffs Harbour, NSW, Australia
Cowsgomoo wrote:
Must say I'm in the remove drive before beaching group.
The drive gets a good fresh water flush and squirt of Lanox once dry. Good opportunity to check for damage etc.

Gets transported in a heavy duty cardboard sleeve now to stop any damage to the fins.


That Lanox is the best natural lube I have found, one squirt before and after sailing and no probs, perfect to keep the AKA pin connector sliding in/out easily too, WD40 dries out to a flakey laquer film, Lanox stays slippery.

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PostPosted: Thu Mar 25, 2010 8:26 am 
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Joined: Fri Sep 19, 2008 4:07 pm
Posts: 397
Location: CLEARWATER, MN
I have been using several US bicycle lubricants as recommended here in the forum. After several hours of vigorous Mirage driving, I can find no trace of the lubricant on drive parts. I have been using the same lubricant on my bike and don't have to lube as often even when pedaling in the
rain. I am wondering if the continuous flushing in the Mirage drive removes the lube much
faster than on a bicycle which is not being hit with as much water.

I done some web browsing about Lanox (Australia) and am impressed with its reputation.
Is Lanox available in US, or does someone know of a better 'marine' lube than premium bicycle
lube?


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PostPosted: Thu Mar 25, 2010 8:43 am 
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Location: Oceanside, California
The Drive chains are self lubricating in the water, so lube is not critical there. I can't imagine a lube staying put when constantly scrubbing while in use.

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Director of Parts and Accessory Sales
Hobie Cat USA


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PostPosted: Thu Mar 25, 2010 9:00 am 
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Joined: Tue Jan 22, 2008 5:47 am
Posts: 71
Location: Fort Walton Beach, Florida
I use (truck)wheel bearing grease when I rebuild my drives from the ground up at the beginning of every fishing season.
I rinse after every trip with fresh water.....

Thats about all the maintenance I do....my drive (ver.1) has been working for the last 6 years.
I have replaced both cams and one chain....but I put ALOT of miles on these things.

Oh and I have replaced countless turbo fins due to the bottom always getting in my way. :roll:

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