Originally Posted by
Doosh
By this, I assume the lever gets soft and comes all the way to the bar?
If so, that's the fluid boiling over. If you aren't already, try a fresh bottle of Motul RBF 600 and be sure to completely flush the brake system.
Could try another fluid.
Sadly, the ZTL system is just tough on the heat. The next step is trying a different pad like the Vesrah XX. After that step, the consider going to a milled-out race caliper. Basically, you take a caliper and remove all the material from each side down to just one seal. Let's a lot more air get in there.
Did these pads come with a perforated stainless backing? If so, why did you remove it?