Hi Homegrown, you don't need a special tool. Turn the block on its side so that you can see the bottom of the gear. Then get something that is the same size (like a socket) and tap the gear until its high enough for the cam to be pulled out
Have a look at my page https://www.renault4.co.uk/forum/threads/look-what-i-found.5611/page-4
Sorry, I said to "tap the gear out". I meant to say tap the bush out. No idea what size the thread is. Renault used to have a special tool to take out the bush