Flex shaft very HOT!!!!

[banixj]

The final part of the strut of my tenshock mono became so hot after 1 second only of middle throttle...
The heat is so high: there's a dilatation and the axle come out a little...
I can fell some vibrations too on the strut (axle cover with the 2 ball bearings inside)...
I know i have a so hard configuration (5100kv@3S) but i think there's something wrong...
I've tried using grease or oil and the peak amp is always around 25A..!!!
Only 5A with motor disconnected from flex...
Here's the pic:

[Basstronics]

Flex on teflon with grease will create drag. Just nature of the beast.

Now are the bearings binding up due to being misaligned?

I would lube up the flex, put back in with motor out. It should turn pretty easy with only resistance being from the flex/teflon/grease. If there is any bind find and fix.

[sanyijr]

You running this out of water at half thottle? You have to have lots of friction to build up heat that fast. As Basstronics says, does the flex roll free if not attached to motor?

[tlandauer]

Same set-up as Ten Shock Samurai, you have either misalignment in the machined part or faulty bearings, spin the bearings and check for problem, also it is common that on the Ten Shock flexcable, the point where the cable enters the stub shaft is not trued, I have several spare ones for my boats and not every one is trued, but I run lower KV motor and don't have vibration , it will become apparent as RPM increases.

[BHChieftain]

Isn't 57,000 rpm a little nuts?
Chief

[banixj]

i've found the matter: the flexi si not aligned with the final shaft... they made a bad soldering...
so what can i do? where can i find a better plug and play flexi??
do you think is better to change bearings too?

[BHChieftain]

Can you unsolder the flex from the driveshaft, then replace the flex? I did that on my tenshock mono1-- I needed to change a motor, then the orig flexshaft was cut too short. I unsoldered the flex from the driveshaft, and soldered in a new flex cut to the right size.

Chief

[banixj]

i think is too difficult...
what i need to unsolder and sold again?
the solder for electric cables is ok?

[tlandauer]

Chief, what size did you use as your new flex cable? .130? My feeling is that the stock cable is just a bit undersized for the stub shaft and it wasn't centered when it was soldered, it will be good to know if you didn't have this problem with your new cable. I might send mine to have it professionally redone.
@ banixj, can you have someone do it for you? I think it is a good suggestion by Chief.

[martin]

It could be that the hole in the stub is over size & or the flex is undersize which would cause a problem re alignment when soldering. But ive seen a few stubs where the hole is drilled offcentre, easy to happen when theses things are being mass produced. I make my own stubs & still have to be carefull that im drilling central when going up in stages off drill diameters, its easy for drills to wonder off centre when drilling deep holes ecsecially small diameter ones.

[tlandauer]

I will never catch up with some of you guys! I am lucky that I can cut the cable w/o cutting my fingers!
Yes!! That could also be the reason, in which case there is no cure for that unless a new stub shaft is made. My RPM is much lower and I haven't encountered any problems yet, was only lamenting the imperfection when one is so accustomed to the quality of flex shaft sold here.

[banixj]

So what tools i need to unsold and solder again?

[martin]

Have you run this shaft in the boat before where it didnt get hot or vibrate & it suddenly started getting hot & vibrating, if so then its prob something else thats wrong.

[martin]

Simple basic check on the shaft & stub is to sit it on a flat surface & roll backwards & forewards with your fingers & see if theirs a wobble on the stub, you can also hold with both hands & twist between you fingers & see a wobble. If the hole is drilled wrong then theirs nothing you can do, also if the hole was to big for the flex it would be very difficult to get the flex centred during soldering.

[BHChieftain]

So what tools i need to unsold and solder again?

On mine, the flexshaft was factory soldered into the propshaft. I used a solder gun (140W), but you could use a standard 40-80W soldering iron wilth a large tip on the end, or a torch to heat up the prop shaft. Then the flex shaft should fall right out. You could either loctite a new flex cable into the shaft, or solder it again. The best tool for cutting the flexshaft is a dremel tool with a cutting wheel.

My orignial plan was to simply replace the entire flexshaft with a standard OSE propshaft, but the tenshock was metric and used metric bearings in the metric strut (which was a tube attached to the stuffing tube), so I would have had to rebult the entire back end...

I used a .150 cable actually-- I might have had to sand it down a bit to fit into the propshaft.

Here's a pic of mine:


Chief