Cham you will probably not be able to purchase any spares for either of your cars at the venue so I would bring a selection of spares with you. Saying that, if anyone racing has a part that you don't carry then most would be willing to help out if need be.
I have carried my radio (steerwheel) and both cars in my hand luggage several times when racing abroad and it normally is not a problem. My advice to you would be to ask at check-in BEFORE you part with your main luggage just in case they ask you to put the radio in there. Be prepared to take everything out though as they normally spot the gear on the scanner and ask you to empty out your bag to check it, which is always fun
