Just refitting my brake caliper to my 5yr old bos deville.
Torque to 12nm and ripped the thread out of the lower

Use a nut and bolt? (Edit: just been working my wife’s old IS mount forks!! Doh – no use for PM)

Helicoil insert?

Helicoil.

Isn’t Deville PM160? No excuse for not using a 4-bolt adapter.

Helicoil and check torque values. IIRC 6mm bolts are usually done to 6 nm

Something like this?

Was the bolt too long, bottoming out before reaching torque?

Edit: Torque value too high as said above.

Seems I’ve been over doing the torque, should have been 6nm.

Will look into helicoil, and cross my fingers.

Thanks for all the comments guys.

Helicoil is fine and will actually produce a stronger thread as it ens up steel on teel not steel on alloy

Really simple to do as well. Live anywhere near Edinburgh I’ll put one in for you. should be £10 – 20 quid at an engineers or even your lbs. Literally takes 5 mins to do as you don’t even need to drill it in ally – just run the tap into it and fit the insert

Thanks for the offer but I’m in Huddersfield.
Will just try a lbs at the weekend.

12nm sounds like a huge torque for a post mount brake caliper.As above, 6nm max, if that.

Insert / helicoil fitted by a decent LBS / engineering firm will get you up and running again so all is not lost.

I have this job to do. The other option, which though much cheaper, is certainly not as good as helicoil. You can tap a new thread to the next size up, and drill out the caliper hole too. A friend did this successfully. There’s not much margin for error, the thread is no stronger than it was, and there might not be a huge amount of material on the post mount, depending how it’s formed.

A helicoil cost a few pennies. A kit including tap and fitting tool can be had for a few quid.
Don’t drill out and retap to a bigger size. You could well be weakening the structure too much