21 Nms Really?

It wants to be nearly twice that, mine is 38NM (BMW) but I'd guess Triumph will be very close. I wouldn't put copperslip or any grease on those bolts though.

 

I've followed the Haynes manual when doing my Bonneville Speedmaster, so I guess I do 21Nm (just checked my manual says that too). I've not had any issues with brakes coming loose, don't use copperslip on them though.

 

Radially mounted calipers like the Speed Twin use larger bolts and higher torque values, hasn't your bike got axially mounted sliding calipers?

 

https://www.thetriumphforum.com/threads/speed-twin-torque-settings.27590/
Will this help?

 

No worries, your choice as to grease or no grease, personally I’d just make sure the threads are clean. Hope you are sorted.

 

I had to Google what radial/axial calipers were, and it seems to me both Speedmaster and Speed Twin are axial.

From online parts diagrams the Speed Twin does have larger M10 bolts compared to Speedmaster's M8 so seems likely it could take more torque assuming same thread depth in same alloy. I must admit to ignorance though as to what is correct thing to do is.

 

Yes, my mistake, I knew the Speed Twin has four piston callipers but I thought they were radially mounted like the Speed Triple.