(T) Stupid 19mm bolts!

Yes, I was just going to suggest what Dave suggested...

Sometimes, you just need a bigger tool...

A long 'breaker bar' with a half-inch drive is a very good investment. Of course if you're using a 3/8" ratchet, you will need to buy the 1/2" sockets as well, but you only need a few sizes so it's best to buy them individually in my opinion... say, 13mm, 17mm, 19mm. You can extend it with tubing as necessary, e.g. for driveshaft nuts. It's much safer than extending a ratchet handle, which will probably break the ratchet anyway and that would be a shame

Also, the sockets will fit MUCH better than a wheelbrace etc. (I use a 19mm socket for my wheelbolts) and with a nice long lever to push on, you shouldn't need to use a hammer. When I do use a hammer, I make it a very heavy mallet-type (club hammer) and I use it with a short, wide ring spanner than fits really well. I wouldn't hit a ratchet handle/breaker bar, as it would flop all over the place. Less energy would be going into undoing the bolt, and more energy to rounding-off the head...

Just my thoughts.
Cheers,
-Alex

I only used a rubber mallet to get the old discs off. Give it a smack from behind to knock the old disc loose.