seehuusen

LOL, yes, I swam in the river too after the floods, debris and all... on second thought, perhaps I shouldn't have
There was a 4 day sting where I came home from work everyday, wet... Missus got suspicious LOL

duckdogs14

Shaft mod question?

How does a 10x4x3 mm bearing fit a 1/8" copped tube sanded down? Isnt 3mm way bigger than 1/8".. Someone posted a boca bearing item number and when I looked it up it didn't match. And help on what size or number needed to do this shaft mod, or anything else to help with cavitating boat?  I have a new prop, have adjusted it all the way back towards the nozzle and back towards the inlet pickup with still loss of suction once it starts to plane. I have trim plates and have done almost every angle to fix it and nothing is working. So I assuming it has to be the slight gap where the shaft comes through the housing.

And help on the correct parts from you pros would be very helpful  =)

DRAGONFIRE81M

First witch drive do u have the copyed one with a 2.3mm shaft or a grumpier drive that has a 3mm shaft witch is what that bearing was for with out haveing to make a new shaft or ordering a grumpier impeller shaft

duckdogs14

IM running the stock shaft

DRAGONFIRE81M

That comes with the nqd witch is 2.3 mm. Btw 1/8" is 3.17mm

n_ahvakana

I am new to RC and I chose the NQD 757 as my first boat, yes stock version is crappy so I upgraded:

-FlySky GT2 2CH 2.4GHz transmitter and receiver

-Seaking 4800kv brushless (watercooled)

-Seaking 25A ESC for brushless (watercooled)

-Gotek 9257MG Metal Gear Servo

-Hobbymate 3S Lipo low voltage monitor

-Stock jet drive

and run one of the following batteries in 11.1v 3S Lipo:

-5800mAh 25c

-2x: 2200mAh 20c

It has been good to me so far but now i'm seeing in the first 5 minutes on running, I don't get as much power as I used to get and the wires from the battery to the ESC are heating up.

 is this because the 3s lipo is too big for the 25A ESC?

 do I need 7.4v 2S lipo's instead or will a higher rating ESC work, say 35A?

 I can add another metal line for water cooling for the wires but that seems unnecessary; I don't want to start ordering parts that I don't need/want before I know what the problem is.

seehuusen

Hey mate,

I'd say that your setup is not very efficient on 3S.
These jet pumps can't run at much more than 28K RPM, and even that is a stretch if the motor doesn't have enough torque...

Your setup, with a 4800KV motor, would be running at more than double the rpm recommended, 11.1 x 4800 = 53280 rpm at full throttle (no load)

That size motor is way better suited a 2S setup, 7.2 x 4800 = 34560 RPM at full throttle (no load)
Take 20% efficiency loss, 34560RPM/ 1.2 = 28800... in the sweet spot now

With the 3S, all the extra RPM would do, is cause more heat and noise... potentially also massive amounts of vibration at full throttle.

Switch to 2S and you will find it runs better, less weight too

sundogz

Yes, I agree, and you need a water jacket on that motor, not a coil of tubing. You may also want to change to at least a 35A esc. I have a 60A in mine for a little headroom.

Another perhaps cheaper route would be to go to a lower kv motor on 3S - 3200kv tops. Water jacket or tubing. That way you may get away with the 25A esc for a while as well.

n_ahvakana

thank you for the advise, I will order a 3200kv motor and see how that affects my set up, and probably a 2S lipo to see how that also affects my set up.

seehuusen

I found a new little piece jet boating goodness 50 meters from my new place... Massive sand flats on incoming or outgoing tides = heaps of fun!
(Minor problem, I can't find either of my remote controls since the move... Half my luck LOL... back to the boxes)

seehuusen

so the bush in the stator (where the drive shaft fits after the prop) was completely worn out, as in, MASSIVE vibrations, so much so that I broke a blade on the impeller!! LOL

I've now glued some 1/8 copper tube into the stator, and it's a longer bush, so hoping for more stability/ less vibration It looks and feels like the goods, will let you know in a later post when I've tested it out in the wet

prontozuk

after starting travel around Australia i went to get the boat out for go up this creek.... and no go. I had lost a bearing in the top of the motor. So now i have to wait a month until i get to darwin to pick it up from a post office. I also ordered a new flexi drive and stainless intake grill.

s2k matt

I have posted and built a couple boats now and I know this topic has been covered in the past, but I need some coupler help as I have been hitting dead ends everywhere I try.

Does anyone have any sources for good couplers, or does anybody produce them on here? I have 3.175mm motor shaft and a stock 2.3mm impeller shaft.

Thanks in advance

sundogz

Get with Steve at SicRc.com. His email is [email protected]

He makes some good quality couplers for that jet drive. I have two of his couplers on my JetCat conversion. Sdg.

s2k matt

Thanks a lot sundogz, he was great and I was able to get them ordered right away. I have been on this for a little while now and he's the first person to really be responsive, awesome! Can't wait to finally get the boat in the water again

sundogz

Glad I could help. Good luck with the build!

hollaendersgasse

hello
I´m a newbee from Germany and want to buy a tear into for small money (for example in Asia)
do you know a link to a good shoPß
thank you very much
hollaendersgasse

Wheelnut

My Feedback: (81)

Here you go.
http://www.banggood.com/Wholesale-NO...t-p-48328.html

similar

Hi there,
It's been a long time since I've posted on this thread, but.....

Does anyone have a link for a video of a modded Tear Into, running I think a Graupner unit on 4s and has an enthusiastic observer saying things like "And that's not fast motion" and "Look at those three sixties, wooooo underwater three sixties".

Tall order I know, but if you've seen the video I'm talking about, you'll no doubt remember it - that thing was a beast

s2k matt

Deleted...

prontozuk

while i travel around Australia i have done another video.

Bluff Reserve, Buchan, VIC, Australia 29th of September 2013.

http://youtu.be/7Exxc7F-kmA

prontozuk

while we travel around Australia I have done another video.

Bear Gully Campground, Tarwin Lower, VIC, Australia 8th of October 2013

http://youtu.be/NWWcrH_EPdE