gmod cars constantly braking.

Hello, guys I really need help

Me and my friend are trying to set up a server but we are running in to an issue that we just can't fix, its when we drive any car and it comes up to a specific speed it just starts to automatically brake, we have TDM cars installed we also have VC mod and Williams car dealer. it's at 70 km/h it starts to break, and we have no idea why plz help.