Minimono Upgrade Drive Shaft DIY

[yoffer]

Ok guys, i know everyone has been having the wire drive failure just like i have. I love the boat, but after only 4 runs in a month because ive snapped one and lost the spare to the depths because of the crappy set screw coupler that comes stock with the minimono i got tired of it. So i decided to do a little research online and pieced together my own custom flex drive wire system. So lets jump on in.

Listed are the parts you will have to order, yours may vary but this is what i used for my system.

Octura .098 Flex Drive Wire, assembled.
http://www.offshoreelectrics.com/pro...oct-oc098L-24c

Octura Coupler
http://www.offshoreelectrics.com/pro...oct-ocfhe18098

K & S Stuffing Tube part# 129
http://www.offshoreelectrics.com/pro...rass-tb&cat=70

*OPTIONAL*
Octura Purple Plastic y531 Prop
http://www.offshoreelectrics.com/pro...?prod=oct-y531

First we are going to start off by removing all the old drive components, you will have to remove the battery/servo tray first, which i used a small flathead screwdriver and pried up on the corners until i was able to use my fingers to pop it out. It is held in by glue. This is what you should see after that is done. (i already installed the octura coupler in this picture)



Next you will have to remove the stock stuffing tube to be able to fit the larger one on. I did this by using a set of pliers and twisting it back and forth until the glue released it and i pulled it out the back. You will then have to drill out the tube holder and the rear of the boat larger to accomodate the larger stuffing tube. Cut your new stuffing tube to length, i used a dremel for this process, do the same for your flex cable, make sure you leave extra room, its easy to cut too much. Hunker the tube down with some glue, later test it in the tub to make sure its water tight. This is what it will look like.



Next on the list is to align it properly to the motor coupler so that it reduces as much friction and premature ware on the drive line. I did this by using the end of a drill bit and pulling lightly over and over again in small incriments to make sure i didnt kink it or bend it too much, i really like the way this boat it setup, i only had one bend that i had to make. When your done, it should like this.



Now go ahead and assemble the rest of system and do a test run on the stand to make sure everything is proper aligned and nothing is catching before you glue back down the battery/servo tray into place. I should mention that the drive shaft prop that came with the system was too small and had a good amount of play in the stuffing tube, i remedied this by cutting a small piece of teflon off what i had left over and slid it over the drive shaft prop with made it fit snuggly into the tube with very minimal resistance, if any at all.
Here it is assembled.



And a shot of the new prop with the bullet nut provided in the ose flex cable system.



Heres a shot of my workstation and my new MC!



First impressions.
I love it. I ran one pack and it was trouble free. The boat sounded quieter, the stock wire drive system seemed to cause a lot of vibration and noise, this new system seems to tone that vibration down a lot. I love the way it sounds, very very little resistance when turning the prop/flex cable by hand. Everything was water tight, had maybe a drop or two in the hull after a 7 minute run. Coupled together with the new prop, this setup seems very good and i plan on running it trouble free for a while. If you have any questions, comments, or suggestions, please by all means share.

[ryin]

I am going to have to give this a try. The only problem I have right now is the stupid set screw coupling always loosens up. I had a nice coupling for my mini rio that helped the shaft from tearing apart, but coupling fits a 2.5mm motor shaft dia. not the 3mm shaft dia. on the mini mono. did you notice slower speeds at all due to the thicker shaft causing more load on the motor?

[yoffer]

No i didnt notice any slower speeds, but quite the opposite lol
I did upgrade the prop and its visually a lot larger than the stock prop, and i did notice higher motor and esc temps. I plan on throwing a watercooler 35a seaking esc in and looking to larger cooling lines to take the temps back down. I think the prop is heating up the motor and esc more than anything.

[gyrotron]

No i didnt notice any slower speeds, but quite the opposite lol
I did upgrade the prop and its visually a lot larger than the stock prop, and i did notice higher motor and esc temps. I plan on throwing a watercooler 35a seaking esc in and looking to larger cooling lines to take the temps back down. I think the prop is heating up the motor and esc more than anything.

Hi Yoffer,

Can you post a picture of the final mod so we can see the interior of the hull with everything in minus the battery? Thx.

[Duke]

Thanks for posting this yoffer , i ran my minimono today for the first time and guess what happened ? yep , down to the bottom went my prop and shaft on the second pack . that was enough to hook me on this little gem though .

[RAMROD5]

Thanks for posting this yoffer , i ran my minimono today for the first time and guess what happened ? yep , down to the bottom went my prop and shaft on the second pack . that was enough to hook me on this little gem though .

you did better than me! my first run with my minimono ended up with the esc exploding, the whole interior smoke damaged, motor mount burnt, and plastic above esc warped....not happy

[yoffer]

Yeah ive had problems with the stock drive system from day one. But i ran over 10 packs with this upgraded system now and not one issue. I do notice more torque lean on full throttle, might be because of the heavier collet on the motor, or maybe the bigger prop, not too sure. But it beats having to worry about the prop shaft falling out.

[Duke]

Yoffer , i got all my stuff today to fix my mini , i think they put a little extra glue on my battery tray lol.

[yoffer]

Yoffer , i got all my stuff today to fix my mini , i think they put a little extra glue on my battery tray lol.

All i did was pry it up starting at the corner with a flathead and i was able to pull it out. Let me know how it turns out.

[alvinm]

I think I might go this route even though this second stock wire is holding up after a few runs. Did you take a measurement of how far you went outside the back of the hull with the brass tubing?

[yoffer]

I took a rough estimate. It's about the same length as the stock tube, maybe just one or two mm's longer.

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[boogityman]

Hey Yoffer,

Great idea for this drive upgrade. I have all the parts in hand and even before installing them I can tell its going to be a lot more reliable than the stock drive setup. Question for you--what did you use to glue the stuffing tube back down? Just some epoxy? Also when you cut the cable drive to length do you have to solder the cut end to keep it from unwinding? I read something like that once I think...

I also managed to pop out the motor mount by accident while prying up the servo/battery tray Was using a putty knife to get under the tray without cracking it and when it finally gave I hammered the motor mount with my hand...whoops. I can either glue that back down or I also have a 3500kV Turnigy outrunner I got from HK months ago and never used that I may just pop in there with a 50A ESC just because its out already...Of course would also love to be able to cram the Turnigy 2200mAh battery I have in there for some longer runtimes too...but that may be dreaming this hull is tiny!

[yoffer]

This is the best I have.


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[gyrotron]

This is the best I have.


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Yes I just wanted to see how everything end up inside the hull once you had finished the mod. Thx.

[yoffer]

No problem, let me know if you have anymore questions. As far as cutting the flex shaft goes, I used a dremel with a cutting circle on it. I didn't solder the end that I cut as I didn't feel the need to but you could if you wanted to.

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[gyrotron]

No problem, let me know if you have anymore questions. As far as cutting the flex shaft goes, I used a dremel with a cutting circle on it. I didn't solder the end that I cut as I didn't feel the need to but you could if you wanted to.

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What is the overall length of the flex shaft?

[yoffer]

I'm not sure, I just measured what needed from the stock wire drive and then I cut 2 inches more so I test fit it and from there I cut small sections off until it fit perfectly

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[Sobie2]

I am upgrading my minimono with the .098 shaft, prop, and either the seaking 35a or 60a esc. The 60a esc can run 4s battery if I can find one that fits. Either esc and prop and driveshaft is $100. I am very new to the lipo thing. So I am looking for suggestions of an upgraded motor. Can the stocker run 4s? Or is there a drop in motor that is better than the stock one for 3s?

I am interested in really spending less than $60 on a motor.

Thx,
Sobie2

[boogityman]

I'm fairly new to this game as well but from my experience working with the Mini Rio there's a fine line between fast & fun and fast & constantly flipping, so I would watch out with that combination. That said, I think you will have difficulty finding a 4s that fits... at least one that'll give you decent run times anyways. I cram a bigger 3s in there to be able to keep it out there longer so its a tradeoff. I have still yet to rebuild mine with this shaft upgrade but am considering using a 3200kv outrunner I have laying around, but that would give me 35k rpm unloaded so its on the higher end of things. If you managed to cram a 4s in there its my understanding that you wouldn't want to put much more than a 2200kv motor on there.

Anyways just my 2 cents

[USMC247365]

All, new to the boating world, last time I played with toys it was in the 80's. I have been doing alot of getting shot at and barely made it back home. I picked up RC's as a way of decompressing and it worked, but it is in depth to say the least. I bought the minimono and it striped the coupler and sucked as bad as you all said it did. I tried this drive upgrade and not only did it haul %ss but it is going to be my pet project. I also got my hands on a Spartan, I love the fact that you guys have answers for every situation, I am happy to be home, God Bless the US and RC I am obsessed. Please let me know tha best battery setup for the Spartan....

[USMC247365]

I took advice and spent a little on upgrade ESc's and put the Lipo power behind it. I truely think that you have to listen to the posts, modify yours, and get some.... As I am a Combat Water Survival instructor I do swim after my flips... and I caught 2 pompanos last night and got diner and a movie..... You guys are AWESOME... Thankx again

[Mr Camil]

Thinking about doing this but completely new to rc boats. What glue would you guys recommend?

[MiniMorris]

How did you drill out the tube holder? It seems there's no way to get a drill bit in there? Also, did you use just regular epoxy to secure the new tube? Thanks

[MAMBA2200]

Grab it with pliers and twist it back and forth it will break loose

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[MiniMorris]

Grab it with pliers and twist it back and forth it will break loose

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So you break out the tube holder, drill it, then glue it back in? What glue should I use?

[tlandauer]

MiniMoris,
Since you are getting excellent advice already, I am not trying to confuse the way you want to fix it, but in your other thread, you said the motor is not center/straight when run at low RPM, you mentioned vibration. To me it seems that there can be two issues, one is mis-alignment, the other is the motor is damaged, the shaft is not straight.
If the motor is good, you should be able to tell if it is aligned with the stuffing tube , the reason I ask is that you only mentioned about this observation when the motor is running.
IMO, a bit of mis-alignment would not cause vibration where as if the motor shaft is damaged/bent would cause some vibration. Granted it is unusual for a shaft to be "bent of out of shape" so to speak, may be that the motor wasn't assembled right to begin with. You also mensioned Not centered: are you saying the shaft doesn't look centered in relationship to the stuffing tube or it just doesn't look centered on the motor by itself?
I would examine all possible causes before doing surgery on the stuffing tube, this is just my opinion if I were faced with this problem, in no way am I putting other's advice down, this being the New Year, last thing I want is misunderstanding.
Cheers!

[tlandauer]

How is your coupler? is it machined correctly? These aluminum things are cheaply made, if itself is out of round, then you don't stand a chance.

[MiniMorris]

MiniMoris,
Since you are getting excellent advice already, I am not trying to confuse the way you want to fix it, but in your other thread, you said the motor is not center/straight when run at low RPM, you mentioned vibration. To me it seems that there can be two issues, one is mis-alignment, the other is the motor is damaged, the shaft is not straight.
If the motor is good, you should be able to tell if it is aligned with the stuffing tube , the reason I ask is that you only mentioned about this observation when the motor is running.
IMO, a bit of mis-alignment would not cause vibration where as if the motor shaft is damaged/bent would cause some vibration. Granted it is unusual for a shaft to be "bent of out of shape" so to speak, may be that the motor wasn't assembled right to begin with. You also mensioned Not centered: are you saying the shaft doesn't look centered in relationship to the stuffing tube or it just doesn't look centered on the motor by itself?
I would examine all possible causes before doing surgery on the stuffing tube, this is just my opinion if I were faced with this problem, in no way am I putting other's advice down, this being the New Year, last thing I want is misunderstanding.
Cheers!

Well, to clarify the motor shaft is straight it's when I put the coupler on motor, if you look at the end of the coupler where the prop shaft attaches you can tell, at low rpm, the coupler isn't on straight be because if you hold a nail against it, the nail will vibrate and bounce, where as it is smooth on the motor shaft side of the coupler. It looks as the motor shaft is straight inline with the stuffing tube. Also, the stuffing tube surgery is so I could use a flex shaft and not have to lose $20 in parts (a wire shaft, prop, prop nut.) everytime a grub screw backs out...... Which is every time it gets put in the water for me.

[MAMBA2200]

those stock couplers are made out of a very soft metal the set screws are junk i tossed mine never used it if you want it i will send it to you

[MiniMorris]

How is your coupler? is it machined correctly? These aluminum things are cheaply made, if itself is out of round, then you don't stand a chance.

Umm ... Well ima newb to the whole boat thing so I'm not sure, it looks alright?