E-Revo Motor blues...

Revision #1:
Tekno Kit using the stock 4146 clutch shoes and 13T/38T with a Traxxas VXL 355 Velenion Brushless set-up. Ran for 15 mins, get performance and runtime with a 3C-5400 Venom LiPo. After the 10th second gear shift the 3.2mm shaft snapped. (w/ bore reducer).

Revision #2:
Same as above but used a CC 5700 w/ MM ESC. Run great for 10 mins and engine and esc overheated. CC5700 got to 300 degrees and ESC 125. Result: melted the solder off wires on the motor side. (w/ bore reducer).

Revision #3:
Same as #2 but with a CC 4600 w/MM ESC. Performance was what I expected, somewhere between Rev 1 and Rev 2. After 6-8 2nd gear shifts the motor shaft broke. (3.2mm w/ bore reducer).

I want to continue running a 3S Li-Po (5400-8000mah) and I want the performance realized with the CC 4600.

What is a good replacement with a 5mm shaft? And is my gearing OK? I'm running 40-series street tires..

Thanks,
Al