Stuffing tube and stinger temp.

[tlandauer]

I was just giving some pre-maiden check on my first build. Hull is MHZ Lizard Xtreme, Leo 4082 2000 kv, .187 cable and all Speed Master hardware.
As I seldom blip my boats on dry land, I have never put my hand over any stinger/strut. So I don't remember if it is normal to get warm or hot. My by boats to date have teflon liners. My build is without. Using K&S 1/4" brass tube. Much to my dismay, after a few blips ( not full throttle) I placed my hand over the stinger and it feels warm, same goes to the stuffing tube. Prior to final assmbling, I checked and checked and double checked, there is no abnormal binding and motor /shaft alignment is good, when the cable comes out of the tube it goes straight into the coupler. . The free-float brass bushing is sometimes turning with the stub shaft. Here is the angle for the tube:DSCN2268_1743.jpgDSCN2301_1774.jpgDSCN2316_1788.jpg

[ron1950]

hate to ask such a dumb question but....did u grease the shaft really well? where did u get the stuffing tube brace i like that....

[masonis1]

Grease it. My cousins traxxas blast tube would get soo hot it would start melting the deck. Nobody knew why.. Finally got tk.loom at it. Nobody.ever greased it. I just sprayed wd40 in his and its ok.

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[tlandauer]

Thanks for the advices, YES, I did grease it with Grim Speed grease and also the grease gun from Proboat. I also use a drop of high temp Trans & Diff Lube 75W-90. I am really puzzled.
@ Ron 1950, I got that from Kintec. My original plan was to use OSE 4074/4082 motor mount and fibricate my own rails , so the rails will extend to the stuffing tube brace, ( the cross member is the same width as the motor mount ), that did not work out so i got the little stuffing support from Kintec and used its side pieces.

[masonis1]

if its still hot i have no idea. if.its just warm.dont.worry too.muxh. in water it will be good

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[tlandauer]

The support is for 7mm tube, I had to put a short piece of 9/32 tube with a cut in that piece. After the cut you need to file away some so the closed dia. of the 9/32 is smaller. Then slide it over the 1/4 tube and jam it in the brace.
@ masonis1, I hear you, I hope water will be a good heat sink.

[tlandauer]

I understand that I might not have a perfect bend, but the warm temp on the stinger just boggles the mind. If the stuffing tube is so hot ( which is not) there is only little chance that heat can transfer to the stinger. The tube only enters the backplate of the stinger. I really can't tell if some heat build-up is normal since I never rev the boat in the dry. This is first time because i want to make sure everything is ok. Is it normal that the free-float bushing turns too? ( it doesn't spin but moves/turns in and out between the stinger end and the drive dog) When i have the shaft out, I turned the shaft in the GREASED bushing and no binding or unwelcome metal grinding feelings. Stub shaft is correct length.

[martin]

The floating bush should do exactally what you describe, you will see it float back & forth & turn but not spin fast. You should notice that it dosnt turn all the time depending on rpm.

[Fluid]

"A few blips...and it feels warm" What does that mean? How warm are you talking about? I strongly suspect this is a complete non-issue - I can't remember ever touching drive line parts while the motor was live (or not) to feel the temperature of the parts...



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[tlandauer]

Well, I certainly wish it is a non-issue, I just placed my hand on the stinger and it was warm, like from friction. ESC was disconnected by then, anyway, thanks---i was hoping to hear someone would tell me i am nuts! ( Not that you have, but I get the drift) Thanks!
@ martin, thanks for clarifying that.

[jimi911]

Where did you get that nice little stuffing tube mount?

[Basstronics]

How tight is the prop shaft in the floating bushing?

Ive had to lightly sand my 3/16" w/.187 cable shafts from Aeromarine. I just spin them up in the drill and use some well used 400 grit.

Most of your friction will be at the sharpest point in your bend. I just went through this and I tried to make the bend as gradual and large as I could.

[tlandauer]

@ Basstronics, the stub shaft is not tight in the floatng bushing, at least not that I can tell, I will spin it in the drill to see if I can improve.
I know the bend will have most friction and I have to recheck that, thanks. I guess I just never expected the stinger will warm-up after few moments of motor reving, most of my boats are either RTRs with teflon liners or built by experience guys, this is my first attempt.
@jimi911, I got it at kintec racing. Please go to post #4 for explanation.http://kintecracing.com/Building_Supplies.html

[1945dave]

Sounds like you know the right answers and your setup looks really good, so my first reaction is to say forget about it. Just for grins and giggles I hooked up a city water adapter to my Leo 4072 and ESC and sitting on my work bench ran the motor up to a fast idle and just felt the drive line and the strut/stinger. It took about five minutes to feel any noticable heat but you could say it was warm to the touch. This would never be a real issue on the pond because even if the stinger got real hot during a run by the time you slowed down and brought the boat in the stinger would be surrounded by water and it would be cool again. The stuffing box tube would hold that temp longer but still who cares? It would not melt the tube or the flex cable and it wouldn't even set the grease on fire so I really can't see where the concern is. Go ahead and run it like you stole it. Forget about it.

Dave

[tlandauer]

Thanks, I know sometimes I am a mental case!