My SCX24 Deadbolt was slower than either the C10 or the Jeep, which both are running the stock motor. The Deadbolt had an 050 Barrage motor with the pinion from the SCX24 motor. This was driving me nuts. The motor would actually stall in a climb that the other 2 could make with ease. So I took the Barrage motor out and put the FF-030 in which is a 100t 030 motor. Should be a tad slower but more torque. Well it would stall on the same climbs as the Barrage motor. Ok lets go back to stock so I put the stock motor back in. To my surprise I got the same results. I was pretty much at my wits end and was ready to make it a parts truck even though it was one of my favorites.
Went upstairs and ate dinner and thought about it some more. It came to me I wonder if the speed switch on the transmitter had gotten changed. It has L, M, H and I keep it in H all the time. So after dinner and some family time. I went back downstairs and looked at the transmitter for the Deadbolt. Sure enough the speed switch was in the L position. Switched it to H, plugged in the battery and woola the normal speed was back. Now if I would have just thought of that before I did all the motor swaps the afternoon would have been much better.
The lesson to this story if your SCX24 slows down before you do anything else check the damn speed switch.