try it
addEventHandler("onClientVehicleCollision", getRootElement(),function (collider,force, bodyPart, x, y, z, nx, ny, nz)
if collider and getElementType(collider) == "player" then
if not isElementFrozen(source) then
if collider ~= source then
if not getVehicleOccupant(source,0) then
setElementFrozen(source, true)
setTimer(setElementFrozen, 1000, 1, source, false)
end
end
end
end
end)