Caliper sliding tube / bolt thread repair . Heli coil thread repair

[audia2owner]

I was changing front brakes on Audi A2, threads on calliper bolts / sliders are disintegrated and rusted on hub carrier. I have re-cut the threads and install a Heli coil to repair this, you need M9 Heli coil kit (M9 Thread pitch 1.25 coil length about 13mm long), kit comes with drill but and thread curing tool and heli-coil insert tool plus coils. If you have to buy new bolts you need 55mm long 12mm wide sliders blots with M9 threads, in my case bolts are good so I have cleans the blots and add copper grease and used.

Drill out the old broken threads. Add lubricants to the drill bit and drill slowly and very straight.

Clean the newly drill hole and inset tap set with lubricant and cut slowly.

cut threads slowly straightly with lubricants. i use socket make cuting tool longer. You can cut from front to make life easier.

use a straight edge to keep the bit straight

Clean the new threads with plenty of break cleaner and dry.

And strongest “thread lock” in to insert/ screw Helicoil and screw from back in to new the threads

Break off the Heli coil spring end

Lever thread lock to harden and put the calipers back in
Tighten caliper bolts and torque to 27Nm

 

[Little Dog]

I know the alternatives are very expensive. I do have reservations though around brakes being held in place with a helicoil that is bonded in position. Are you sure this repair is totally safe? If so it’s good one.

 

[vagdream]

I know the alternatives are very expensive. I do have reservations though around brakes being held in place with a helicoil that is bonded in position. Are you sure this repair is totally safe? If so it’s good one.

I would not worry particularly about using Helicoils as long as they are in a suitable material as most jet engines will be utilising these wire thread inserts and an Inconel X750 insert is easily good for 1000 degree operation.