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Another mirage drive failure - time for improvement?
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Author:  coastbum [ Sat Feb 22, 2014 6:28 pm ]
Post subject:  Re: Another mirage drive failure - time for improvement?

I've broken 8 of these new shafts. Never broken an old one. Hobie needs to address this problem. I'm tired of buying replacements. I'm also tired of my calf heeling when the pedal breaks off and the top of the crap shaft slices into my leg. Can someone provide more detail about the old solid shafts? Do they work with the Hobie pedals like we use on newer ones? Do you have to also order a screw in shaft for the pedal? Or are you stuck using bicycle pedals?

Thanks!

Author:  CR Yaker [ Sat Feb 22, 2014 7:17 pm ]
Post subject:  Re: Another mirage drive failure - time for improvement?

coastbum wrote:
I've broken 8 of these new shafts. Never broken an old one. Hobie needs to address this problem. I'm tired of buying replacements. I'm also tired of my calf heeling when the pedal breaks off and the top of the crap shaft slices into my leg. Can someone provide more detail about the old solid shafts? Do they work with the Hobie pedals like we use on newer ones? Do you have to also order a screw in shaft for the pedal? Or are you stuck using bicycle pedals?

Thanks!


Only 8? Why be concerned now? LOL, heck I've broken only one and I'm already looking for an alternative.

Author:  fusioneng [ Sun Feb 23, 2014 6:30 am ]
Post subject:  Re: Another mirage drive failure - time for improvement?

Coastbum:
If you have indeed broken 8 pedal shafts recently during normal use then this is very telling to the rest of us. All of my experience is on pre 2013 model mirage drives ( about a dozen different drives since 2007 never having any issues). My 3rd TI was purchased in mid 2012.
I pedal my boat at least 15 miles a week all year round in all conditions. One question I have is if you have a newer drive it is covered under warranty for two years, basically if you walk into any dealer they will change the shaft for you ( no cost at all to you). Knowing my dealer if they had a customer that had 8 shafts replaced just recently, they would have the president of Hobie on the phone after the third one demanding resolution ( assuming it costs the dealer a couple hundred in labor out of their own pocket to repair the unit each time).
Personally after the second unit I would have slipped a solid 3 inch sleeve made out of stainless into one of the broken units and either epoxy it in or drill two 8/32 side screws to hold it in place and call it a day (no tools needed besides a hack saw and drill).
Alternately on the third new shaft (replaced by the dealer under warranty) before trying to use it I would do the epoxy drill bit trick, if you do the drill bit trick do not cover the drill bits with anything as that would render the fix useless. Drill bits are cobalt steel and being completely encased in epoxy water can't get to them anyway.

If you want to go way overboard on the fix if you go to someplace like MSC (basically any mail order tool supply) and order four 3/32 tungsten carbide drill blanks (they are really cheap) and drop them in (one in each corner inside, then embed the works in epoxy, that joint will withstand well over a thousand lbs of force (way overkill), which is way more than the shaft itself can withstand (you could literally put a brick under each end of the shaft on the floor and stand in the middle).

I'm trying to help you personally here trying to come up with a solution that will fix your problem, I don't give a hoot about Hobie or what they do about it, as long as they get this obvious material supply problem solved by the time I buy my next mirage boat. If what you say is true I'll not be recommending anyone buy a new Hobie mirage boat until this problem is solved ( buy used only pre 2013 only)
Hope this helps
Bob

Author:  Zenyak [ Tue Mar 11, 2014 11:13 pm ]
Post subject:  Re: Another mirage drive failure - time for improvement?

Dang, I think I followed most of this thread. Was thinking of investing in a new drive as my old V1 needs a new sprocket and there is a lot of extra side to side play on the main spindle. Perhaps I'll just upgrade the sprocket for now. Can understand main abuse being continuing to apply pressure at the end of the stroke, but also agree that one should be able to apply a lot of pressure to these things without worrying they will fail.

Author:  fishwhisperer619 [ Wed Mar 12, 2014 6:08 am ]
Post subject:  Re: Another mirage drive failure - time for improvement?

fusioneng wrote:
Coastbum:
If you have indeed broken 8 pedal shafts recently during normal use then this is very telling to the rest of us. All of my experience is on pre 2013 model mirage drives ( about a dozen different drives since 2007 never having any issues). My 3rd TI was purchased in mid 2012.
I pedal my boat at least 15 miles a week all year round in all conditions. One question I have is if you have a newer drive it is covered under warranty for two years, basically if you walk into any dealer they will change the shaft for you ( no cost at all to you). Knowing my dealer if they had a customer that had 8 shafts replaced just recently, they would have the president of Hobie on the phone after the third one demanding resolution ( assuming it costs the dealer a couple hundred in labor out of their own pocket to repair the unit each time).
Personally after the second unit I would have slipped a solid 3 inch sleeve made out of stainless into one of the broken units and either epoxy it in or drill two 8/32 side screws to hold it in place and call it a day (no tools needed besides a hack saw and drill).
Alternately on the third new shaft (replaced by the dealer under warranty) before trying to use it I would do the epoxy drill bit trick, if you do the drill bit trick do not cover the drill bits with anything as that would render the fix useless. Drill bits are cobalt steel and being completely encased in epoxy water can't get to them anyway.

If you want to go way overboard on the fix if you go to someplace like MSC (basically any mail order tool supply) and order four 3/32 tungsten carbide drill blanks (they are really cheap) and drop them in (one in each corner inside, then embed the works in epoxy, that joint will withstand well over a thousand lbs of force (way overkill), which is way more than the shaft itself can withstand (you could literally put a brick under each end of the shaft on the floor and stand in the middle).

I'm trying to help you personally here trying to come up with a solution that will fix your problem, I don't give a hoot about Hobie or what they do about it, as long as they get this obvious material supply problem solved by the time I buy my next mirage boat. If what you say is true I'll not be recommending anyone buy a new Hobie mirage boat until this problem is solved ( buy used only pre 2013 only)
Hope this helps
Bob


I'm sure there's a lighter material that can be used besides tungsten

Author:  Tom Kirkman [ Wed Mar 12, 2014 7:12 am ]
Post subject:  Re: Another mirage drive failure - time for improvement?

The fix may already be available, provided Hobie still has some of the older crank arms (right in the photo below). You can quickly identify them by the rounded top which lacks the plastic cap of the newer hollow crank arms.

Image

These are the 2nd generation drives and upon comparison I can see no outside dimension differences with the newer drive crank arms so they should be a "bolt in" piece. However, because they are interchangeable, it is very likely that Hobie discontinued them and is servicing the older units with the newer arms, if any of the older arms were to break. They are solid, a little heavier, but I have never heard of one breaking.

Author:  fusioneng [ Wed Mar 12, 2014 8:39 am ]
Post subject:  Re: Another mirage drive failure - time for improvement?

fishwhisperer619:
I wasn't talking about replacing the whole shaft with a tungsten carbide mirage shaft, adding tungsten carbide shafts to you mirage drive would add at least ten lbs weight to each drive, the force required to break that shaft would be well over 10,000 lbs of force (might be overkill for some), and the cost would be prohibitive (around $5000).
The difference in weight between HS steel drill blanks (.0049 lbs ea) vs tungsten carbide blanks (.0119 lbs ea) is minimal, and the carbide blanks only cost a little more (I'm guessing around the $2 bucks ea).

Here is a chart showing roughly how much weight would be added for each style of repair option (just a really rough estimate (+/-.01 lbs)), Personally I'd go for the solid carbide shafts ( joking).

Image

It's suprising how heavy the solid stainless steel shafts are, they add 4.4 lbs to the weight of the mirage so instead of 6 lbs (ea mirage drive) they would now be ten lbs ea.
My little fix with eight 3/32 dia carbide vs eight HS steel drill blanks adds .76 lbs to the weight of the entire unit over the HS steel fix, but doubles the break failure force. Realistically you probably only need 2 drill blanks in there to make the shaft virtually indestructible.
A stock mirage drive weighs 6 lbs, if you add my little mod with HS steel blanks the mirage drive the new entire mirage drive weight would be 6.457 lbs, with the carbide blanks the entire mirage drive weight would be 6.513 lbs

Bob

Author:  fishwhisperer619 [ Wed Mar 12, 2014 9:30 am ]
Post subject:  Re: Another mirage drive failure - time for improvement?

fusioneng wrote:
fishwhisperer619:
I wasn't talking about replacing the whole shaft with a tungsten carbide mirage shaft, adding tungsten carbide shafts to you mirage drive would add at least ten lbs weight to each drive, the force required to break that shaft would be well over 10,000 lbs of force (might be overkill for some), and the cost would be prohibitive (around $5000).
The difference in weight between HS steel drill blanks (.0049 lbs ea) vs tungsten carbide blanks (.0119 lbs ea) is minimal, and the carbide blanks only cost a little more (I'm guessing around the $2 bucks ea).

Here is a chart showing roughly how much weight would be added for each style of repair option (just a really rough estimate (+/-.01 lbs)), Personally I'd go for the solid carbide shafts ( joking).

Image

It's suprising how heavy the solid stainless steel shafts are, they add 4.4 lbs to the weight of the mirage so instead of 6 lbs (ea mirage drive) they would now be ten lbs ea.
My little fix with eight 3/32 dia carbide vs eight HS steel drill blanks adds .76 lbs to the weight of the entire unit over the HS steel fix, but doubles the break failure force. Realistically you probably only need 2 drill blanks in there to make the shaft virtually indestructible.
A stock mirage drive weighs 6 lbs, if you add my little mod with HS steel blanks the mirage drive the new entire mirage drive weight would be 6.457 lbs, with the carbide blanks the entire mirage drive weight would be 6.513 lbs

Bob


That's the last time I ever question your posts haha. Can't argue with the evidence. Also I knowbyou didn't mean the whole shaft, I thought you meant dropping a rod in the shaft.

Author:  mmiller [ Thu Mar 13, 2014 8:34 am ]
Post subject:  Re: Another mirage drive failure - time for improvement?

Fyi... we are on this. There are likely some production issues that contributed to an increase in failures. Alloy and hardness can cause issues, but we are planning some changes to the extrusions for wider margins of safety. We are also testing 100% of stock here.

The primary modes of failure seem to be use with Turbo fins and possibly longer legged users (Stronger? Not sure). To put this in some perspective... Actual replacements of pedal shafts is a VERY small percentage compared to current year production... <.000?% The number of replacements this year includes all reasons for replacing a shaft for all years of production.

Author:  CR Yaker [ Sat Mar 15, 2014 12:41 am ]
Post subject:  Re: Another mirage drive failure - time for improvement?

mmiller wrote:
Fyi... we are on this. There are likely some production issues that contributed to an increase in failures. Alloy and hardness can cause issues, but we are planning some changes to the extrusions for wider margins of safety. We are also testing 100% of stock here.

The primary modes of failure seem to be use with Turbo fins and possibly longer legged users (Stronger? Not sure). To put this in some perspective... Actual replacements of pedal shafts is a VERY small percentage compared to current year production... <.000?% The number of replacements this year includes all reasons for replacing a shaft for all years of production.



Sounds great Matt that your on it. I don't understand what your saying here?

"To put this in some perspective... Actual replacements of pedal shafts is a VERY small percentage compared to current year production... <.000?% The number of replacements this year includes all reasons for replacing a shaft for all years of production."

Are you saying there is an increase in failures this year compared to other years? Are you saying you need to replace all of this years shafts? Kind of confused as to what your saying here but good to know that you guys are on it.

Thanks
Mark

Author:  fusioneng [ Sat Mar 15, 2014 4:35 pm ]
Post subject:  Re: Another mirage drive failure - time for improvement?

For those who happen to have one of the newer mirage drives and are worried about the pedal shaft possibly breaking especially if you are a hard pedeler, or are very tall or large, and you don't feel like tearing your mirage drive apart to fill the shaft with epoxy and drill blanks (or old drill bits) like I described above, here is a really simple fix to the problem. If you take a piece of 1/8" x 1/2" x 2" long piece of aluminum (available at Home Depot or Lowes for a few bucks) and attach it to the front side of the shaft (the side facing you) with two stainless 8-32 flat head screws (attach the screws above and below the weak pin joint where the pedal length adjustment pin goes thru (the weak spot in the design), of course you will need an electric drill, a countersink tool, and an 8/32 tap. I typically clear coat or paint any aluminum and screws when I install anything onto my boat (salt water).

Here is a video of the stress analysis. This simple fix raises the safety factor of the joint to above the failure point of the metal, so it should never fail.
As I showed earlier, without the fix just applying 100 lbs force to the pedal (from your foot) is more than the metal could withstand, and would always fatigue and fail after several 100 lb loads (breaking the shaft). If I owned a new mirage drive I would do this fix just for my own piece of mind.

Here is the FEA stress analysis.
[youtube]http://www.youtube.com/watch?v=N9eZ-OYsC6Q&feature=youtu.be[/youtube]

Hope this helps
Bob

Author:  Gas Yakker [ Sun Mar 16, 2014 8:06 am ]
Post subject:  Re: Another mirage drive failure - time for improvement?

Bob,

Always love a FEA :).

Doesn't the plastic pedal adjustment handle interefere with this fix? There isn't 1/8" between face of shaft & inside face of the handle arms that hold the pin, at least not on my drive. They're basically touching.

Am I missing something?

Author:  fusioneng [ Sun Mar 16, 2014 1:35 pm ]
Post subject:  Re: Another mirage drive failure - time for improvement?

Oops ( DAH)
I have a mirage drive in my cad system but I never drew in those plastic levers. I was wondering why no one had tried my epoxy fix with the drill bits, and tried to think of an even simpler fix that people might actually attempt, it looked great on the cad and the math worked, however I never walked out to the garage to actually look at the drive before posting.
I thought it was a great idea at the time, oops.

It's back to the drawing board, I'll keep trying to come up with a quick simple fix that actually works this time.
Bob

Author:  GB2 [ Mon Mar 17, 2014 5:13 pm ]
Post subject:  Re: Another mirage drive failure - time for improvement?

The easiest solution is to buy the V1 shafts and pedals and replace the V2 shafts. I searched the web and could not find any reports of the V1 shafts failing. I built my own stainless steel pedal shafts but with a hand drill, it was not easy or fun. http://www.norcalkayakanglers.com/index ... ic=52116.0 The V2 shafts are fine for light recreational use but are not reliable enough for those peddling long distances on the ocean and far offshore. The Island sail package puts more stress on the drive shafts because of the increased weight, water resistance and wind drag and increase the likelihood of failure. The replacement V1 shafts and pedals will cost you about $70. Well worth it if you are 5 miles off shore, IMO.

Author:  Roadrunner [ Mon Mar 17, 2014 6:24 pm ]
Post subject:  Re: Another mirage drive failure - time for improvement?

GB2 wrote:
The easiest solution is to buy the V1 shafts and pedals and replace the V2 shafts.
I think a little clarification is necessary. What is generally considered a "V-1" Drive (pre-2009) does not have "V-1" cranks. Crank arms have been hollow since about 2005. Today's crank arms are actually a second generation hollow shaft, which is stronger than the original hollow arms. Remember, in those days there were no Turbofins, no AIs, nothing to overtax the crank arms.

What GB2 probably is probably referring to are the solid billet aluminum cranks, PN 81100001 (left) and 81105001 (right). Yes, they are very strong -- pretty bullet proof as far as I know. These list for $31 US each and do not come with pedals. Most standard bicycle pedals can be used (need left and right thread, 9/16" I think) -- you supply your own. You can even install quick release pedals if you like. These are the ones (or similar) to that which Tom Kirkman describes above (right crank arm in his picture). They are in fact, fully interchangeable with current crank arms and you can transfer the pins and pin retractors as well. There are two versions of these, but the differences are not significant. I've had both versions in the past and have had no issues with them. They were standard equipment on all early series Drives until 2005. Whether Hobie actively stocks these or they are just old overstock I don't know, so I would say if you want some, don't wait too long to order them! 8)

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