New Sprockets and Masts for Mirage Drive

Here's a close up look at the newest masts and sprockets for the Mirage Drive. I understand these are standard on all the '09's and can be retrofitted to the older Drives as well. They are already available and I have a set installed in conjunction with last year's redesigned drums and chain/cables. IMO, these latest upgrades finally make the newest Drives superior in reliability to the venerable old "stainless" drives (which we rarely use any more).

This is what the old (left) and new sprockets look like next to each other.


Notice the slight difference in color between the sprockets. The newer sprocket is a little harder and should have excellent wear characteristics. Obviously the Allenhead screw is gone and we should expect to see the end of "sprocket wallow" with the brass insert.

Mast installation is simple -- drop some Locktite Blue in the hole and screw the mast in (a screwdriver slot is conveniently located on the opposite end of the mast. No need to orient the mast slot, no more worries about screw tension or backing out.

Here's a cutaway showing a cross section of the insert. Nicely engineered, with flanges to prevent backing or turning.


This next view shows the mast. It uses a heavy shouldered, shallow thread pattern to maximize strength.


Bent mast? I bent one of these and had no problem straightening the mast without removing it from the Drive. Actually, it would be difficult to straighten any other way because of the potential for damaging the threads.

Cost? About $60 for a set of 2 sprockets and 2 masts. You must replace mast and sprocket together, but you can do so one at sprocket at a time.

Downside? Better not forget to use the Locktite (Blue). It works great as a thread locker and these need to be locked in. If you loosen them for any reason, re-apply new thread locker.

Overall evaluation: These should eliminate the last of the issues that have occasionally come up with the old sprockets, especially when using Turbofins. The Hobie engineers have done a great job of improving the ruggedness of the Mirage Drive to handle the heavier demands necessitated by the newer series of fins. Finally!

Do you need it? You should inspect your masts to insure they are not twisting or moving in their sprocket holes, and that the Allenhead screws are not backing out. If you have a problem, there are 3 options:
1. clean and epoxy the joint together;
2. replace your old sprocket with another one (still available)
3. convert one or both sprocket/mast sets to the stronger latest version.

Between #2 and 3, I think your money is much better spent on the later!

PS -- Matt Miller has posted part numbers here:
http://www.hobiecat.com/community/viewtopic.php?t=10306

Thanks for the info Roadrunner- impressive cutaway which details the improvement well!
So, finally a Rnkster proof drive?

As always Roadrunner you have provided excellent info and outstanding photos.

I have, so far, avoided the standard plastic sprockets in favor of the stainless steel. Hard turbo fin use on the Island demands a higher level of durability and reliabilty not provided by the standard plastic sprockets.

Now, finally, the dreaded allen screw is gone and we have a brass insert for strength. Great!

I have no doubt that the turbo mast, with locktite, screwed into a brass insert will exhibit no wobble between mast and brass insert. I do wonder if over time the brass insert will wobble/loosen inside the plastic. The wall of plastic surrounding the brass insert is kinda thin if one views the mast and insert now as one piece. Brass will expand and contract with temperature change. Thousands of pounding reps & constant vibration will be at work. I guess time will tell if the brass remains captured by the plastic

I think welding the turbo mast to a Stainless Steel sprocket to be the ultimate in strength & durability. However, this 'metal head turbo freak' is willing to give the newer sprockets a chance. They are unarguable much better than the old plastic sprockets.

Yakaholic

Stringy, I do think the Drive is now pretty close to bullet proof, but Rnykster proof? He is to Mirage Drives as Michael Phelps is to swimming, Tiger Woods to golf. He was able to destroy a Drive so fast that he needed to carry an extra as a back up. He could disable the stainless steel models as well as plastic. So I really want to say yes, but Rnykster was uncanny! I say this out of deep respect.

Yak, you know I've always been a big fan of stainless sprockets. I have the old aluminum frame units and have never had a problem with them. My first plastic model in 2006, in contrast, broke down several times when Turbofins were added. But the newer design had some potential -- more streamlined, lighter weight, pitot tube capability (which I love), no more chain skipping. The problems that I had made me start paying more attention to the drive. As a result, I learned how to operate the Drive in various states of disrepair. I also learned how to tune and care for it and this has improved its reliability and efficiency for me.

Hobie has made a ton of incremental improvements since then. Better material and assembly control, redesigned pedal cranks, drum axles, drums, chain/cables and sprockets. Today's Drive is a different machine than the one that I got 2 1/2 years ago.

The last malfunction I experienced was the preliminary stage of a wallowing sprocket, which I reset in epoxy. That was over 500 pedaling (not including sailing) miles ago and well over 400 boat wake sprints.

Hat's off to Hobie for their commitment and success in overcoming these obstacles. A far easier (and much less expensive) direction would have been to discontinue the Turbofins.

There are a couple of reasons why I think the newest Drive is better than the stainless sprocket models. 1) Stainless has never overcome the tendency for chain skipping. This is not a problem for you because you keep your cables properly tensioned. Most people don't though. 2) Several of the other parts have improved over the older models. Cables have better crimps, current drums are nylon with glass to make them wear much better on the axle shaft; axles are now splined to improve their stability, etc. These parts not only last longer, but improve performance IMO.

So I'm a convert. My old stainless drives sit in the garage ready to take over whenever the new Drive fails. They've just been collecting dust lately. I've even been thinking about selling them. On the other hand, I'll probably just keep them for their historical value!

I think I remember seeing detailed instructions with pictures for changing sprockets. I think Road Runner posted them... but I can't find them. Anybody know where they are?

http://www.hobiecat.com/community/viewtopic.php?t=10710&highlight=tuning

Those replacement instructions were great. I did the replacement including the sprocket guards on two drives last weekend and this step by step covered it all.

Thanks to all who take the time to write up and post all of these "how to" instructions.

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Roger
http://www.aldenofsunapee.com/
http://www.NEKF.com/

My i 9 inflatable arrived today---it was the wrong color (yellow instead of sage, but in retrospect, I think the yellow is safer. I had a problem earlier this year seeing some kayakers in neutral/dark colored hulls in rough moderately rough water in San Franscisco bay--and the bright color seems like a safety feature.

Now to the drive masts. I asked the shop person for the ST turbo fins--I said that they were the new type on all the 2009 inflatables. He was not at all aware of the difference and insisted that they were all of the same. So..when I got home, i found that I do indeed have the new brass inserts, and of course the old style masts don't fit. The shop tech suggested I just swap for the older allen set screw drives. I suspect that I am better off waiting for the threaded rod masts. I assume that these are available? Any comments? Also could I just thread the rods which come with the older style masts?

Thanks.

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Bob Austin
Pensacola, FL

Hey RR,
Thanks for the update. I agree--these new threaded masts and metal inserts look like a huge improvement over the shift from SS fittings to the plastic parts and Allen screws that I complained mightily about when they first came out over 2 years ago.

http://www.hobiecat.com/community/viewt ... stic+parts

Although I have no problem with my original 2004 SS mast holders, I also have no plans to shift to the Turbo fins, so I think I will stick with my original all-metal Mirage Drive, an oldy, but goody!

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Hi Dick,

I agree, your stainless model is a sturdy unit and for those fortunate enough to still have one in good condition, there would be no reason to upgrade. I also still have a pair of old Drives from 2000 and have never had any problems with them.

Nevertheless, the '09 Drive IMO, should prove to be an equally sturdy unit with one nice advantage -- there shouldn't be any sprocket skipping! With their lighter weight and easier tuning, I rarely use the old Drives any more.
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Bob, I don't know what to say about your dealer, except to suggest that he spend a little time getting to know his products. Surely it must be embarrassing to learn about the newest features from your customers!

First of all, your inflatable Drive is unique in two ways:
1. The well plug (that rubber piece that is attached to the back of the Drive) is shaped differently to better fit the unique inflatable Drivewell shape.
2. I believe your drive comes with a wrench for a quick breakdown of the pedal cranks for compact storage. I can't remember if the cranks are actually different of not.

Most importantly though, the threaded masts for '09 were specifically engineered to improve the reliability of the Drive and ease of installing Turbofins. IMO, they represent a significant upgrade.

Yes, you could swap -- an older Drive would work but not with the ease and utility of your inflatable Drive. You'd certainly be trading down.

Your Dealer gets a D- for product knowledge and advice. You might want to find a more capable party to install the Turbofins or just do it yourself.

The new drive comes with a pedal crank wrench? I wonder if the crank attachment is the same as with the older drives? I've been removing the cranks for tansport, but it is kind of a pain. This winter I'll upgrade to the threaded masts. Would they make it more practical to remove the fins and masts for transport instead?

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Frank
2007 Oasis

If the pedals are removable, does that mean you can replace the Hobie pedals with bicycle pedals?

I've put clipless pedals on my drives but had to buy threaded cranks.

Hobie keeps making the Mirage drives better and better.

Hobie INFLATABLES come with a 9/16 wrench to assemble/disassemble the crank arms. The others do not, but it's easy enough to take them off if you want to.

All current pedal/cranks come as one assembly and will not accept conventional pedals. Technically the pedals are removable but the shaft is pinned and not replaceable. You can adjust for lateral clearance (access by popping off the end cap), but that's about it.

Hobie used to use threaded anodized billet aluminum crank arms and still probably has some leftover in inventory. They're heavy but very strong and ideal for adapting to the clipless pedals as tilroh has. Tilroh, how are the clipless pedals working out?

My two drive assemblies are only 141 difference in seriel numbers! (Revolution is older than the Inflatable). Yes, the peddals and bars are able to be taken down with the wrench, but a socket set is much much faster. The spash skirt is identical in both units. I have interchanged them between the i 9 and the revolution, even with the different retaining mechanisms.

Roadrunner, thanks for the feedback. I have to say that the owner of the dealership was out racing his Hobie cat in celebration of the anniversary when I picked up the inflatable--but it was the person who seems to do the technical work I dealt with. They had just sold two i 14's, last week, so inflatables were not new to them. I'll have to wait until Tues or Wednesday to talk to the owner.

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Bob Austin
Pensacola, FL

Ok, I'm doing the switch from Stainless to the new V2 sprockets - a big step for a die hard Stainless Steel sprocket & turbo fan.

There are a some "gotchas" in the installation that need a little attention by the installer.

First. The V2 sprockets have plastic burs on the interior where the sprocket guard holes are drilled. Before putting sprockets on shaft you need to clean out the plastic chaff & burr holes to keep sprocket to shaft movement smooth.

Second. Forget trying the use a screwdriver to screw in the mast shafts into the sprocket. The brass opening of the sprocket has 5/8" of brass shoulder before one hits the actual threaded section. The brass shoulder to mast tolerance is so tight that the mast nearly has to make its own threads when inserting. Because you start "screwing-in" the mast before you hit the threads I suggest measuring the depth of the brass sprocket and marking that on the mast. That way you know how far you need to go. I found the mast bottoms out 1/8" before the mark - likely because the brass insert is not threaded all the way to the bottom. To get mast all the way in use a VISE-GRIP.

Now this very tight shoulder on the brass insert I find a good sign - means more strength and no chance for wobble or dwell.
Considering the lock-tite and very tight fit I doubt they will be easily removed.

Third. After I got it all assembled and adjusted all the cables properly I was disappointed to find that when cycling the drive though its motion that it was far from smooth. The chain would catch and pop near the end of the strokes. Wha...
Ok, the plastic sprockets have a master center tooth larger than the other teeth. Stainless Steel sprockets have no such center "big tooth". Seems like all the catching and binding was related to that plastic center tooth.

Also, in the manufacturing process the plastic mold seam is also right on that fat tooth. Hmm... OK got a fingernail emery board and went to work sanding away the mold seam on the fat tooth. Took 3 tries sanding, assembling and disassembling before I was happy with results. Removing the seam and tapering the fat tooth slightly did the trick. Having the chain bind is no way to use your drive! Now it is smooooooth when cycling thru the drive.

I have only been on the water once with the new V2 & turbofin combo on the older mirage drive but, so far, I am impressed.
The dwell/wobble of the cotter pin/SS combo is totally gone. The entire range of motion while pedaling is very smooth and quiet.

I will report back once I have sprinted a few times more.

Looks like if one pays close attention to all the details this will be great!