Zener diode response time
Consider the two components in red below: -

The resistors in red are the only paths for current to flow when the transistor is attempting to clamp. Ask your self how much current they are going to shunt away and whether they are actually the right values.
A voltage clamp works by taking a large shunt current. Having a 100 kohm resistor in series with the transistor is not going to pass more than a few tens of micro-amps when the 36 volt is exceeded. This does not constitute a clamp in my book.