i have a teu-104bk speed control in my tt-01. I use a castle cc-bec with the esc because the futaba R603FF rx requires power and the esc does not provide power to the rx. i use a futaba s3305 steering servo and Dragon Red 5000mah 2s 30c lipos. my gearing is 25t/55t. Here's my problem:

i run the car at medium to heavy throttle for 10 mins or so and the speed control shuts off, leaving the led on the esc glowing solid red. the heatsinks on the esc are warm to the touch, not terribly hot at all. the motor is well below 120 degrees f. If i shut the esc switch off and back on, i can run for another minute or so and the same thing happens.

this happens with a 27t fantom, a 19t speed gems, and a 18t speedworks can. I don't recall it happening with the silver can that came stock, but that motor is long gone. i have a fan installed to a motor heatsink that sits above the esc and this doesn't seem to prolong runtime at all. the specs say that the esc should handle motors down to 25t, but I've read that people have had success running 19t motors with it.

any idea what could be happening? any similar experiences? any suggestions for an esc that will run the modified brushed motors as well as brushless ones?

here are the esc specs from tamiyas page:

The Tamiya TEU0104BK is a compact forward/reverse Electronic Speed Controller. The TEU-104BK is equipped with a battery cut-off function to prevent over-discharging of the battery and is compatible with LF batteries.

Specs
Size: 39.4x36.5x15mm. Weight: 47g.
Input voltage: 6.6-7.2V.
Can be used with Sport Tuned Motors (Item 53068) and 25T and above motors.
Battery voltage cut-off function can be disabled.
Compatible with Tamiya and other makes of transmitters.
The setting button allows the forward/reverse and neutral positions to be easily set.
The reverse function can be disabled.
Features heat and current protection functions with LED indicator.
Forward (100%) and reverse (50%) output.
Maximum continuous current of 60A forward and 30A reverse.
Equipped with an aluminum heat sink.
Comes with pre-wired Tamiya style battery connector.
When using Tamiya LF batteries, please use the battery included exchange connector.
Requires BEC plugged into receiver.
*Please note: When used with high geared machines such as Rock Crawlers, protection functions may stop operation due to excessive motor load.
*Always use receiver with BEC. Using other receivers may result in malfunction of receiver.

Your ESC have a problem...I think you need to replace it.

First indicator is the fact that it is unable to power-up your receiver.

nah dawg, that's part of the specs. does not provide power to rx.

Tamiya ESCs can be confusing, they are different than most all others.

The specs aren’t calling for an external BEC, they are saying you must use a receiver with BEC. Meaning a receiver that can handle the main pack voltage, the ESC does not regulate the voltage down to traditional radio levels. I don’t know if the Futaba R603FF is capable of such.

When they say the BEC must be plugged into the receiver, they are referring to the 2 wire connector from the ESC, needs to be plugged into the receiver.

EDIT: To clarify, you can use an external BEC, just not required. If so don't plug in the 2 wire connector from the ESC, but be sure to insulate it/prevent any shorting.

Sounds like your issue is the lipo low voltage shut off is engaging. Either that or simply overloading with too much motor and/or too much gearing for the ESC.

Ah ha. Weird. I think I might simply be over loading it. The low voltage cut off is actually quite worthless on this esc, it's for LiFe batteries and set very low. Low enough that it would damage the Lipo if I actually relied on the low voltage cutoff. I use an external alarm. I'm going to mess with the gearing to reduce load.

Good catch on the cut off, LF means LiFe, duh.