1990 Brembo calliper with ISO M12 x 1.75 pitch high tensile screws refusing to seperated from their beloved callipers.

Using part of the broken screw, and the correct Thread Die, the Co-Axial indicator allows us to position for the removal. [Note: when more precison is required <0.02mm. then a high resolution DTI is used.]

Step 1. Mill a flat surface on the errant screw.

Step 2. Centre drill, Drill upto orginal tapping size, examine thread integrity. Then drill to correct size for HeliCoil tap. (Existing thread was damaged, and as a safety critical item, an insert was required) full thread length engagement was achieved.

Step 3. Tap with Helicoil threading tap, the insert correct length helicoil (Stainless Steel)

After helicoil is installed, the thread tolerance is inspected by using a Screw Thread Plug Go/No Go Gauge Class 6H.

All ready to be safely fastened using new high tensile screws (Grade 8.8 Minimum).

if screws are difficult to remove, torque values may exceed fastener Proof strength, if in doubt replace them.

if replacing original medium (8.8) or alloy (10.9) steel fasteners with Stainless Steel, Grade A4-80 are the absolute minimum grade that are close to grade 8.8. (do so at your own risk).

Best wishes John.