i got a hpi rush evo and when my car is runing and i have the wheels off the ground and i give it gas only the back left wheel is spinning fast when i pull the throttle but the right wheel does not spin fast like the left wheel what could the problem be

Is there a rock in the right tire. just check cuz that happend to me. also try spinning both the tires and see if the right one is harder to spin.

That is completly normal. Its a limited slip diff and both tires will not spin at the same time. If you give it gas and hold 1 tire the other will spin and vise verse.

no it does not have a rock in the tire when i turn the wheel wit my hand it turns nice a smooth i dunno what can be wrong

maybe you stripped a dif gear or 2...open it and check it out

If you stripped one side of the diff it would not move at all. Like I said hold 1 tire and the other will spin switch to the other and the opposite will spin. Its normal. Just like a car. If both rear tires spun at the same time the steering would suck. You dont have a problem!