● An assistant to remove / install the spring on the cylinder head of camshaft.
● Before remove the spring, fixed A1156-12 in the positioned plate and loosen
   the bolt.
● Open A1156-12 carefully, unloaded the spring and take it off.
● Close A1156-12 to tighten the spring while installing it. To match the bolt to 
   hole, and locked.
● Applicable : BMW N42 / N46