OUTRUNNERS??? and cooling????

[LOVE6S]

I have just bought a DF 36 hull and hardware from a member, I bought two outrunners also to put in the boat, its a twin with CF mounts, I was going to get a couple of the water cooled mounts from FC and put them between the motors and CF mounts, FC seems to be on hold at the moment, any ideas where I can get them and do you think I really need them, I am sure it would help cool them some. Any input would be great, thanks guys, Shawn.

[keithbradley]

Do your outrunners have holes in the front on the can or the sides (are they covered by the motor mount)?

[LOVE6S]

Do your outrunners have holes in the front on the can or the sides (are they covered by the motor mount)?

Keith, they are FC 3740 outrunners, the mounts are solid cf. so I would say yes the front is blocked.

[keithbradley]

The 3740s still have vent holes at the sides, so you should be fine with the CF mount. Some inrunners, like the 3126 model, have only holes drilled in the face of the front endbell. In that case it's best to drill holes in the mounts so they are still vented.
Expect a little higher motor temp compared to water cooled, and a little more heat in general under your hatch. They should work fine in a reasonable setup though. They are a lot bigger than what you need in that hull, so they shouldn't get too hot under normal conditions.

[LOVE6S]

The 3740s still have vent holes at the sides, so you should be fine with the CF mount. Some inrunners, like the 3126 model, have only holes drilled in the face of the front endbell. In that case it's best to drill holes in the mounts so they are still vented.
Expect a little higher motor temp compared to water cooled, and a little more heat in general under your hatch. They should work fine in a reasonable setup though. They are a lot bigger than what you need in that hull, so they shouldn't get too hot under normal conditions.

Thank you keith, do you know any tricks to get a collet of the flex shaft, Brian couldnt get it off, I have not tried yet, I was thinking of heating it up with my solder iron, thanks Shawn. Should I drill some holes anyway?

[keithbradley]

Try loosening the set screw.
Kidding...

Seriously though, is the set screw stuck or is the collet stuck on the shaft? Heating will usually take care of loctite so if it's the set screw that may be your fix. If it's just the collet stuck on the motor shaft, maybe try some penetrating lube or stick it in the freezer overnight, then tap it off.

[LOVE6S]

Try loosening the set screw.
Kidding...

Seriously though, is the set screw stuck or is the collet stuck on the shaft? Heating will usually take care of loctite so if it's the set screw that may be your fix. If it's just the collet stuck on the motor shaft, maybe try some penetrating lube or stick it in the freezer overnight, then tap it off.

HA HA, good one, its stuck on the flex, I just dont want to ruin the flex getting it off, thats why the seller left it on, I will spray som penetraiting oil on it and let it set, I cant wait to get this boat going, thanks.

[iridebikes247]

As keith said they will run a little hot but that hull isn't too big so you should be ok. I would bring a temperature gun along for the first run, also have you seen thrust bearings in the store here? Outrunners should usually be run with a thrust bearing in boats they go between the motor mount and flex coupler.

[LOVE6S]

As keith said they will run a little hot but that hull isn't too big so you should be ok. I would bring a temperature gun along for the first run, also have you seen thrust bearings in the store here? Outrunners should usually be run with a thrust bearing in boats they go between the motor mount and flex coupler.

why are the bearings needed on a outrunner?

[BHChieftain]

Soldering iron or gun on the collet works wonders!
Chief

[Prop-a-Gator]

why are the bearings needed on a outrunner?

I only looked into this recently thanks to the knowledgeable people here.

The only thing resisting the trust of your motor is a little circlip. It also transfers that load axially into the side of your front bearing inner ring - which was not designed for that. My FC 3740 started out with zero play axially when pushing on the end of the motor shaft. After about 6 runs without a thrust bearing, there is noticeable play. (maybe 1/2-3/4 mm?) Something moved/deformed/wore. One of the circlip ears also broke off. Not a good sign, but better to notice now than have a catastrophic failure at 35k rpm. (or more )
3740+Outrunner+circlip.jpg

You can buy the thrust bearings here on OSE or other places like HK - if you like to wait.

My problem with the thrust bearing: It cannot sit flush with the motor mounting face. The motor shaft is actually 8mm dia and steps down to 6mm after it exits the motor. The 8mm portion protrudes ~2-3mm from the mounting face. I can use a large washer to take the thust on the front of the motor mount, but then I will not have enough shaft or stuffing tube clearance for the coupler. Anyone done this with a typical water cooled motor mount? Photos?
3740+motor+shaft+diameter.jpg

BTW... I thought the FCR and Turnigy outrunners were clones, but the FCR was shimmed = zero play. (see above pic) The Turnigy 3740 I ran previously had no shims and thus had 1-2 mm play out of the box. Since the magnets pull the can/magnets/shaft towards the motor mount and the prop thrust pushes it away - that circlip can take a beating if there is a gap.

Hope this answers your question LOVE6S, and hope someone can help with my question.

[LOVE6S]

I only looked into this recently thanks to the knowledgeable people here.

The only thing resisting the trust of your motor is a little circlip. It also transfers that load axially into the side of your front bearing inner ring - which was not designed for that. My FC 3740 started out with zero play axially when pushing on the end of the motor shaft. After about 6 runs without a thrust bearing, there is noticeable play. (maybe 1/2-3/4 mm?) Something moved/deformed/wore. One of the circlip ears also broke off. Not a good sign, but better to notice now than have a catastrophic failure at 35k rpm. (or more )
[ATTACH=CONFIG]81259[/ATTACH]

You can buy the thrust bearings here on OSE or other places like HK - if you like to wait.

My problem with the thrust bearing: It cannot sit flush with the motor mounting face. The motor shaft is actually 8mm dia and steps down to 6mm after it exits the motor. The 8mm portion protrudes ~2-3mm from the mounting face. I can use a large washer to take the thust on the front of the motor mount, but then I will not have enough shaft or stuffing tube clearance for the coupler. Anyone done this with a typical water cooled motor mount? Photos?
[ATTACH=CONFIG]81260[/ATTACH]

BTW... I thought the FCR and Turnigy outrunners were clones, but the FCR was shimmed = zero play. (see above pic) The Turnigy 3740 I ran previously had no shims and thus had 1-2 mm play out of the box. Since the magnets pull the can/magnets/shaft towards the motor mount and the prop thrust pushes it away - that circlip can take a beating if there is a gap.

Hope this answers your question LOVE6S, and hope someone can help with my question.

I have the FC 3740"s also, mine will be going on a carbon fiber plate mount, if I understand what you are saying, I should not have clearance problems as the plate is only a few MM thick, is that correct?

[iridebikes247]

You won't have clearance problems, I think Prop-a-gator ran into a problem because he used a water cooled mount. Like you said the carbon fiber mount is pretty thin, way thinner than something water cooled so no worries it should all work out. Hope the chargers are working well for you! Thanks again for such a quick payment LOVE6S.

[Prop-a-Gator]

That's right. LOVE6S will be in much better shape than me. He will just need enough carbon plate thickness to clear the 8mm dia portion of the motor shaft and circlip. (see the gap under the thrust bearing in my second pic above) I measure that to be about 4mm from the face of the mounting surface. He'll also need a hole big enough to clear the circlip ears. (I assume it stays even with the thrust bearing used.) That will require about a 14-15 mm dia hole. The thrust bearing I have is 14mm OD. So even if the carbon mount is thinner than 4mm, he'll need some type of washer anyway.

[LOVE6S]

Well I got the stuck collet off finally, is there anyway to prevent that in the future? Looks like I will have to enlarge the holes in the cf plate to fit the bearing thru, will that be ok when I go back to inrunners?