burning out motors

i have a savage with a mamba max and 4s true rc lipo...i just burned out my second 9xl in a week the first i attributed to the fact that i crashed and smashed the esc...now i have a new esc and motor and all of a sudden the car stopped and wouldnt stop cogging, i checked the motor and it was 258 yup, that'll kill it...why on earth did this happen? the esc was 165 and the battery was 125...i was running for about 30 min...im running a 20t pinion and a 49t spur. i was doing some high speed runs if that makes a difference. is it possible that the brakes are rubbing a little and causing the heat?...they seem to catch very slightly, i dont think it would be enough to cause this though...im obviously doing something very wrong, any help would be appreciated

also, the shrinkwrap on the negative deans connection on the battery split open (melted?)

i just did some testing...the car will cogg indefinitely from a standstill but if i give a it a good push and ease on the throttle itl go but i cant punch it i have to ease in, and in about 30 seconds the motor was 150 and the esc was 190...will a dead motor make the esc heat up like that?

any help i can get here is great, im completely stumped

[brushlessboy16]

did the rotor de-mag?
if so how much for the can?

[suicideneil]

Whats the final drive ratio of the savy? 20/49 sounds very high, but I dont know what the diff ratio is on that truck. Seems like running the truck up and down at high speed with high gearing is only going to have one result, especially with a feigao (they all run hot regardless). A de-magged motor will pull huge current as the weaker the magnet, the higher the motor Kv becomes, and high Kv = high current draw- hence the hot esc etc.

[brushlessboy16]

full reduction ratio is
13.29804 : 1

this i what Brian's calculator says for my setup

Differential Ratio: 3.3076923076923075
Transmission Ratio: 1.640953716690042
Other Ratio: 1
Spur Tooth Count: 49
Pinion Tooth Count: 20
Total Voltage: 16.8
Motor KV: 1853
Tire Diameter (inches): 5
Tire Ballooning (inches): 0
Motor Current Draw: 0
Motor coil Ω: 0.0092
Spur/Pinion Ratio: 2.45 : 1
Total Ratio: 13.29804 : 1
Tire Circumference (inches): 15.71 inches (398.98 mm)
Total Motor Speed: 31130.4 RPM
Vehicle Speed: 34.82 mph (55.94 km/h)
Estimated Adjusted Speed: 33 mph (53 km/h) - 4% loss
Effective KV Value: 1853
KT constant: 0.73 oz-in/A

[brushlessboy16]

a few seconds too late :)

haha lol

so do you think going to a 52 tooth spur would make much difference? is this most likely my problem?

[brushlessboy16]

id check for driveline drag first...

then check your pm box..

[E-Revonut]

def sounds like you where drawing a lot of current with lipo temp of 125. My 8xl went with my MMM, I didn't know the motor had went until I hooked it up to my MM, it worked but after giving it a little throttle with nothing hooked up to it for about 15 seconds my esc was already at 160. The feigao motors are a cheap entry level motor but I'll never run one again. With gearing for 35 in my E-maxx my 8xl was running 190+ with a heat sink. Save up some money and get something a bit better, the Medusa motors are only about an extra $30 from Mike compared to the Feigao

i think im going to leave the gearing the same and check temps like every three minutes, this is weird i didnt seem to have problems before with the 9xl...is there a limit to the amount of time i shoud run? or is it all dependant on temps

although i had never done successive speed runs before, could it be that the large pinion is only causing heat issues only at high speed, because ive done general bashing in the dirt and stuff at lower speeds for a while (mostly staying in first gear)

and would changing the timing on the mm do anything? its set at default now, i think its "normal"

[tc3_racer_001]

go for the lowest setting.

ok, thanks, do high speed runs cause heat more than low speeds?...or is something else going on here

[brushlessboy16]

depends how much airflow your getting thought the truck

well i have a hole cut in the front and back of the body...could it be that i just need to take it easy with the feigao and not run a full pack without stopping?...its just that 258 seems ridiculously high

[brushlessboy16]

yeah it is.. :D umm im stumped