they expand because they can't provide the current draw from the motor. it happened to a trakpower lipo i had a while ago. you pretty much can't use them afterwards safely...

The big packs are only 15C though...:thumbdown:

for an 8000mah pack thats fine... plus you will get amazing run times
only down size is weight ;)

My Medusa is really powerful, I get wheelies if I push it, far more top end than the top nitros and stuff - I couldn't ask, or need any more power, it's excellent!

what gearing are you using though? i am using 47/16 and it didn't seem that quick. could have been my old mamba max esc though now i have a mamba monster so we shall see. i hopefully have 2 5s and 2 4s lipos on there way so i should get some decent run times :thumbsup:

can you use mechanical brakes on a 8th electric?? if so how ?

Electric:

48/15 - which according to "The Speed Calculator" is geared right on for 40mph (slightly less in fact). With your gearing, you have geared for more speed (47 will give higher top speed than 48, and so will a 16 over a 15). I think you would want a 15T pinion on there instead.

Jono83:

You can use mechanical brakes with 8th Electric. Basically you need an ESC where drag brakes can be turned to 0%, or completely off, and where braking force can also be reduced to 0 or off. Then use a servo + brake linkage set-up as normal. This servo is best used with 3rd channel mixing on your transmitter (where it plugs into the 3rd channel port on the Rx but acts off the 2nd Channel movements). This means that the ESC is not told to do anything other than 'stay at neutral' whilst the servo moves into braking and vice versa. This saves battery life.