Scalextric Sport FF motors where are the brakes

I bought a couple of Scalex cars one an Escort with this slim motor in so i decided to put a faster one in it a 25K Sport car goes very well but hates slowing for corners rolls well though, i have tried gears from 3 to 1 to 4,4 and a half to one no go before i throw the motor off the top of the local flats any ideas cheers Keith.