TheOtherSide

Stock couplers do not do well long term... they'll vibe the poop out of your equipment. I have 15-20hrs on my Graupner u-joint without a problem. Here's a copy/paste on an email I sent a guy on this part:

Graupner u-joint: Scroll 3/4 of the way down the page... it's part # 355.4, and I drill out the 2mm part on a lathe with a 3/32" drill bit to make it 2.3mm exactly. If you don't have access to a lathe, just drill as straight as you can. doesn't hurt to buy 2 of them... they're cheap and take a bit to come from the UK.
http://www.cornwallmodelboats.co.uk/...-graupner.html

sundogz

2.3 to 3 or 3.17mm couplers are pretty much non-existent for some reason. If you're not equipped to enlarge holes properly, email Jeff Wohlt ([email protected]) about making you a custom coupler. Or better yet - get several, sell the others on this forum for a little profit to lessen the cost of yours. I had Jeff make some for me a while back that had 3 setscrews around the perimeter so I could eliminate any possible wobble by judicial tightening of the 3 opposed screws. He did a great job. I'm still running those couplers on some ABC Hobby Jet Ski's that we set up for racing (with that same 3900kv motor, by the way).

TheOtherSide

Valid... if anyone needs a Graupner one modded... let me know and I'll be happy to buz one up for you. I currently have four 355.4's ready to be modded for anyone...

MikeHRC

Some help please - I have 2 Tear Into's, both with the same motor (but different ESCs) however they sound very different - one is much louder (and a bit faster). What could be causing this ? Is it down to spacing of the impeller ??

Thanks Mike.

sundogz

The loudness might be caused by impeller clearance. But the one with the highest pitch (note) should be fastest. If not it may have a slipping coupler. I don't think the speed controls are the reason for the difference in sound.

MikeHRC

Thanks - how should I set the impeller clearance ? I only mentioned the different ESCs as I believe that the timing can make them sound different if that is different.

ISIRC10

I know this may seem a bit daft, but are both escs propperly callibrated? If not, then that could also be a reason for the speed difference (I had a 2-prop boat with the same problem, caused me many headaches untill I realised my stupid mistake). Or it could be that one of the escs is rated for less amps, and is struggling to deliver the amount of amps the motor requires. These are just two suggestions (if sundogz's suggestion doesn't fix the problem)

**Edit: timing can make them sound different - an increase in timing can make a motor go faster, but must be done carefully as it may cause unnnecesary amp draw/heat build up and sync loss with the esc

Stein

I just order 2 but if you can get me one modded for a good price shipped to Canada I would take one. I have this motor [link]http://www.hobbypartz.com/07e-c-sl-10t-2848-blue.html.[/link] How much for one modded and shipped to New Brunswick Canada?

Thanks,

sundogz

Mike: check to see if the impeller is contacting the stator or sides of the intake cavity. If so, remove the offending plastic - or better yet, run it until it wears down (more fun). You didn't say if that was the one that was faster.

ISIRC10: It may be so, but I've never compared identical esc's set to different timing side by side. I don't see where different timing would sound any different - they are just 'firing' at different times during the cycle is all. But your suggestion of them not being initially calibrated would be valid if the trigger was held to a different position when initially plugged in, or a different TX was used when initially fired up. But I don't think that is the case.

Stein: You're talking to the wrong person. Write Jeff Wohlt at the email address I posted. Hopefully, he can help you.

MikeHRC

The noisier one is faster. I'll check the impeller. They sound different throughout the throttle range, not just top end, I'm not convinced that they are calibrated perfectly - I have 2 different Tx's and no manual for the Traxxas one - it is a bit of a guess

sundogz

Yes, what I meant was is the noisier one also the one with the highest pitch (note)? Have you checked for a slipping coupling in the noisy boat? You may be onto something with the two transmitters being used. Hope you get it figured out.

ISIRC10: I take that back; if the timing is different it could effect the sound since the motor would have the potential to run at a higher top end (all things considered). I should have thought that through. Sorry Ivan, my bad. Good observation.

ISIRC10

No problem sdgz... sometimes it seems like one needs a phd in electronics to post here - some pretty complex problems we run into

prontozuk

I had a drive of my new boat with the standard 9.6v and then 7.4v and 11.1v and it is night and day with responsiveness and power. I actully dont mind the amount of grunt it has with the stock motor. I just need to upgrade the ESC, servo and receiver to something more usable as I been reading that some people have been having issues tracking down a coupler to adapt brushless motors to the outdrive.

Is there a cheap brushed ESC out there that people have been using as the only one i can see is one from Traxxas.

Thanks James

sundogz

Proboat makes a nice [link=http://www.ebay.com/itm/Pro-Boat-Waterproof-ESC-Reverse-4-8-12V-PRB2314-/130566218456?pt=Radio_Control_Parts_Accessories&hash=item1e665a62d8]40A esc[/link] that won't need water cooling, but the stock motor won't handle a 3S lipo very long. Better get some [link=http://www.ebay.com/itm/Mabuchi-Electric-Motor-RC-Tools-Car-Etc-RS-380PH-/230538474989?pt=Radio_Control_Parts_Accessories&hash=item35ad29f5ed]spares[/link] - they are cheap enough. And put some holes in the transom to facilitate easy replacement of the motor with a screwdriver or long hex wrench. You can cover the holes with hatch tape.

prontozuk

Thanks for the headz up sundogz I will have a look at that ESC. looks easy. Still have to cut the main hole in the top to get at eveythings.

thanks James

prontozuk

Hi All,

I have decided to go all out.

My thought and would love peoples opinion.

2040SL 4800kv Brushless Inrunner http://www.hobbyking.com/hobbyking/s...Cooled%5F.html
Turnigy Marine 35A Brushless Boat ESC http://www.hobbyking.com/hobbyking/s...idProduct=7377
Traxxas High Torque Servo Waterproof http://www.amainhobbies.com/product_...rvo-Waterproof

the reason for the 2040 inrunner is i don't need a coupling.

Also another question. With both the ESC and motor it requires water cooling. Were have you placed the jet (in and out) and which one have other people used for it.

Thanks James

swervyn

Hello to the brains trust

a few questions people may already haver the answers for:

the brass bushing at the end of the prop shaft seems to have reamed out of its housing, slid down the shaft and allowed to impeller to wobble and shred itself on the sides of the intake .... tried super glue but no good, so cut a few notches on the outside of the bush with a hacksaw blade and set it in using a 2 part body filler, seems to have worked ok just wondering if this is common or if there is a better way to avoid it happening in the first place?
Has anyone tried fitting the intake for the motor & esc cooling inside the water intake housing rather than the jet outlet? ie: an intake either side aft of underneath the coupling? So that the impeller draws water into the cooling tubes rather than possibly reducing thrust by diverting it through the cooling tubes after it passes the prop?
Also the stock coupling seems a little short with a new motor if the shaft is set back into the brass bushing far enough to not come out? Is there an easily  available longer 2.3mm coupling? I am assuming the coupling should be fitted so that it rests against the seals at the rear of the jet unit? (unsure exactly what these seals are or whether they should be replaced?) seems about 5mm longer would be handy or a better alternative?

thanks in advance for any help

hqdby1

Well in my water cooling system I have done as you say, but with a slight modification. I also drilled a hole in the jet drive outlet and attached the tube there, but without actually putting a pickup on; the tube is just on the hole. This way the pressure from the jet outlet and the swirling water causing centrifugal force both work together to force water through the pipe. Then the vacuum pressure from the outlet hose (as the impeller is sucking water, just like you were saying) adds to the flow of the water cooling further. But the best thing about it is it hardly effects thrust!

sundogz

That has been tried before. You don't want to draw water from the intake area as that is negative pressure and will not flow water (it actually draws water!). That is maybe why Hqdby1 had to resort to adding pressure from the nozzle to get some flow. Adding a pickup in the nozzle doesn't seem to lower thrust appreciably - at least none that you can tell by running it. I've done it both ways. And to see that stream from the outlet is reassuring that things are getting sufficient cooling. The 'o-ring' is to help keep grease in the shaft bore and as you found when fitting an aftermarket motor the coupler is too short to hold it in place. A longer coupler would be handy here. Let us know if you find a source.

aum-offshore

hi....





[youtube]http://www.youtube.com/watch?v=28H5Kq1UYrA[/youtube]

prontozuk

Hi aum-offshore,

wow. that is awesome. I don’t suppose you have an English version or maybe even if you like email me the editable version of yours and I can get it converted.

Did i mention that is awesome.


Thanks James

murmuzy-tearinto

I had the same issue with my stock coupler. with the new motor it shortened it and I ended up destroying a prop and shaft (check out the damage on pg. 91). What i've done now is file the flat spot on the shaft all the way to the top so you can get an extra 4ish milimeters.

murmuzy-tearinto

I've finished the build, finaly. This is one gutsy set up I must say. 3900kv motor, 55a esc, 3s 2200mah 40c. ZINGZING

sundogz

Which motor is that? Looking forward to a video!

sundogz

You might have accidentally pulled the shaft out of the bushing trying to fit the coupling (which is short with aftermarket motors) letting the bushing come out of place. The impeller normally holds the bushing in place. Only other thing that could cause that would be if the impeller spun loose on the shaft.