Fatstogey

I mean i can read that your not supposed to. I wanna know why.

ESC can handle it? Motor cant handle it? Truck can handle it?

What is the reason?
Has anyone tried it?
I wouldnt think it would affect teh ESC. And the motor is friction less however i would assume higher powers would produce more heat. But higher voltages should produce less heat? Or is the motor stronger too the point that at that voltage it will draw to many amps?

Or is it prone to mechanical failure at that high an RPM(or an attempt to reach that rpm).

Kinda hoping some money bags on here will give it a shot. lol Im not takin a chance with mine.

badassrevo

iTrader: (12)

It will spin the motor too fast and it will come apart. The RPM's will be too high.

OG RC 10T

iTrader: (41)

Product design.

TomTomTuning

iTrader: (19)

3s lipo = 11.1v
11.1v x 7700K = 85470 RPM

Which is over what they are rated for.

But i know people have put 4s on the 5700K motors, so I'm sure someone had to put a 3s on a 7700K.

Fatstogey

Well i understand that but i wanna know specifically what fails. Will the higher rpm cause the rotor to go outta control? Will it cause higher heat that breaks down the motor? Will it cause higher current draw than the ESC can handle? Or will it simply tear the transmission to shreads.

Also you must remember. That rpm is unloaded. Loaded its attempting to reach that rpm. And in doing so it will dram more amperage. Im thinking that it will cause too much heat and or draw too much current for the ESC to push.

But i dont think that the motor could have a mechanical problem. Because its frictionless. So it shouldnt have a problem with higher rpm.

kurt.

iTrader: (19)

physics



the magnets basically explode.

geeunit1014

iTrader: (14)

You could, but the motor wont last very long. Extreme RPM's for extended periods of time will kill the motor. I actually hear of people who build drag rails who run 4s on the 7700, but they only get away with it because theyre only running for about 1 second at a time...

If youre looking for a reliable 3s setup, go with the 5700. For most cases that will be more power than you ever need Think about it this way. The traxxas VXL setup that does 70mph on a 3s is a 3500kv motor. just think how much more retarted it will be with an extra 24000 rpms

Fatstogey

Yea but how is that? IN a brushed motor the electro magnetic field is whats spinning. Inside a fixed magnetic field. The device changing polar orientation is actually the moving part. Also the brushes create friction.

Where as in a brushless there is no friction other than in the bearings. If i was to try id try to find some better bearings for the motor first. And the fixed magnetic field is that of the armature(not sure if thats what youd call it in a brushless but the brushed equivalent of the moving part of the motor). So its the fixed magnetic field that rotates within the electro magnetic field. So nothing should fail mechanically due to friction. And it shouldnt go out of balance unless there is a failure due to heat or or shorting out. Causeing total failure or an out of balance electro magnectic field. Throwng the armature out of its alignment. The only way it could fail is electrically.

But does it just fail and stop? Or does it blast it out of alignment and break into pieces.

Id guess the most likely problem would be getting too hot and burning the insulation of the motor windings. Due to a higher current draw trying to achieve 80k rpm. Because if you had the motor unloaded. Once it hits the top rpm it believe the current will be at 1 amp. But its higher than 1amp in its attempt to reach that speed.

So im wondering if i could make myself a custom badass heat sink and fan for the motor and avoid the higher heat in the motor. I know they have them but i could make myself a higher performance sink and fan. Or if the power would be high enough to simply short it out before it fails due to heat and i shouldnt even bother.

Fatstogey

Well basically i wanna try a high speed run when i get a radar gun. I got a t4 and i wanna see how fast i can get it going on the pavement. I was gonna lower the truck to the ground and throw a 3s on there just to try high speed runs. Also if they are dragging it would be drawing higher amperage. I want to accelerate slowely(draw less amps) to see what kinda top speeds i can get on a long run.

If you throttle up slowly then it shouldnt be a problem. Because amperage draw will be lower. I got other things i wanna buy first but i think im gonna get a 3s and give it a shot in a month or 2.

Jrz13

if you want some more speed go with custom gearing, that motor isnt going to take that 3s very long. honestly you would have been better off with the 5700kv motor if you were doin speed, runs

rearviewmirror

iTrader: (17)

Chuck Norris runs his 6900kV on 6S....just sayin'....

Fatstogey

No chuck norris runs 1.21 gigawatts.

shinta

iTrader: (1)

im not all up on a lot of things seen as im must starting out but form what i under stand the 3s you taking about a lipo battery and the mm7700 is a brushless motor right?

if im right, and slow start would seem like it would work, but i do know one thing, i would get all steel or alum gears all the way around, before i tried. as well as gearing the trans high as well, as well as lowering it a lot like a few mm form the ground. i know cars not so much rc cars but i know cars, i owned a geo storm with a skyline gtr awd motor and trans, and i had it at stock ride hight and being the smart person that i am, i was on the highway and punched it and the front end lifted off the ground at 180mph, thing god i was smart and put a fill roll cage in it, but still ended up spending 3 days in the hospital.

you could put the motor on a dino and get it up the the rpm your trying to get. im shear there is a ways to find out how much amperage its takes as well as what brakes in the motor, but i know there not cheep ether.

i say go for it

Fatstogey

Well there is an aluminium transmission housing available. Ill be getting it after i paw a few bills. But ive yet to find any aluminium transmission or spur gears. Im baffled that no one has done this. Im trying to start a business now so i dont have tons of money to waste. But i did A/C work for a guy with a shop doing industrial metal work. But in his shop he had helis that he made custom aluminium parts for. I might go back there and see if he can replicate my transmission, spur, and differential gears. However im sure hell be cool about it. And i could try to trade him some A/C work for it. But i doubt it would be cheap.

But i cannot believe that no one has made a fully aluminium or even steel driveline for the t4. I know id buy one for sure. They have the transmission case in aluminium but thats it, that i can find. Ive been searching for those very parts. Some day ill just have some custom ones made for myself. But given the power of these new brusless and where things are going i cant believe this truck doesnt have metal gears.

But yea if i do it ill zip tie the a arms to the shock tower. I was also thinking about putting buggy tires on it as well. If i can get a long enough run and start slow enough it should be fine. The question is how long will it take to get up to that speed without me accelerating too fast and drawing too much current.

I may also get another rear wing and cut it into pieces and bolt it to the hood to get more frontal downforce. But that will also create more drag and increase amp draw so i dont know if i should or not. ACtually you know what id just put a little lead in the front. Although the wing would only increase the weight at speed rather than actually carrying weight.

ALLERACER

iTrader: (2)

You also could run into problems with the ESC. I know in plane ESC's there has been problems running high rpm's. It won't kill the ESC but it won't run the motor that fast.