Nissan Repair: Nissan Quashqai brakes, vacuum booster, nissan quashqai

Question
Hi,
We have purchased a second hand Quasqai 1 month ago.
It is 2 years old and we have progressively been experiencing difficulties with the brakes.
When pressing the pedal the car doesn't brake in proportion and then catches up only when reaching a certain point of pressure on the pedal. This translate in a sudden strong break which projects us slightly forward.
This is obviously quite uncomfortable and potentially dangerous, particuarly for cars behind.
It also tends to happen more in the morning when the car is cold.
The Nissan dealer is telling us that this is a normal feature of Nissan but we find it hard to believe as we feel that this is potentially dangerous.
I would welcome any comments or suggestions from the experts.
Best Regards,
Laura

Answer
Laura,

The brake booster is out of adjustment.  I say this due to your description of the problem.  There is a rod that pushes against the back of the master cylinder when you press the brake pedal.  At a very early point of its travel the vacuum booster aids you in the force required to activate the brakes.  What is going on is the rod is out of adjustment, or the booster is defective in its action.  That is what I would tell the dealer to look for.  If this is not the problem then look at the brake pad material and to see if the rotor surfaces are work hardned.  That is, the previous owner really overheated the brakes and the metal surface is really shiny with a blue shade to it.  If there is enough thickness the rotors can be turned.  If not they would need to be replaced.  Those are the two things I am aware of that would cause dlate and hard application of brakes.