[pierremcalpine]

Here's what I ended up using as a counterhold. Not as easy as I thought but very do-able. The challenge is to manage the recessed harmonic balancer screw holes. You cannot simply tighten two pieces off metal up against it. In my case I bought a bunch of 5/16 washers and put them behind the two screws to raise the counterhold suffiently. Also, you'll need to buy 2 M8 screws which for me were twice as long as the HB bolts. Lastly I ended up having to grind the edges off the ends of the metal pieces to ensure there was still room for the 30mm socket in the centre. In the end, I did all this only to find out that I had already sufficiently tightened the centre bolt!!!