how meny mm to take out the back of the flywheel??

[joegtir]

Does anyone know how much you can get away with taking off the back of the flywheel , i've tried mesuring on one of my 5s but im finding it hard as the engine and box are in the car , what im after really is the depth to go , its a bit rough but i can see it starts to be cut out after 20mm from the starter teeth then goes for about 40mm, raises a bit and then meets the standard hight just before the crank bolts . If anyone can help out would be much appreciated.
thanks

[bye_all_c_ya]

i try and find out what i had taken out of mine as my dad does them