03 pilot - uneven braking

[pilotnooker]

I have noticed last winter and this fall that in the colder mornings my car brakes unevenly just in the morning. So I apply constant pressure on the brake pedal and the car brakes, then the pedal drops a little more and the car lurches and brakes much harder. This did not happen during the warmer months. It has not dropped below freezing yet, so I know it is not water freezing in the brake system etc. I changed the front brakes and the brake fluids last winter and this did not help, the back brakes are still good.. The pilot just had it states inspection and the tech gave it the all ok.. This problem just happens for the first few minutes in the morning and then they work fine for the remainder of the day.

Any ideas, why this is happening just in the mornings, just when the car is cold, and just in Fall and Winter?

[94eg!]

So when the pedal drops like that, the car suddenly brakes harder?

If so, then I would say something may be up with the power-booster (but I don't know what). That or perhaps the check-valve on the vacuum hose from the booster to the intake manifold is going bad (getting stuck). If a stuck check valve suddenly opened, the booster would instantly work harder. Kinda like an extra kick to the brake pedal.

If the car brakes less when the pedal drops, then I would say the master cylinder is going bad. When the piston seal inside the master cylinder starts going bad, it allows fluid past and back up into the reservoir. I've experienced this on several old hondas. Your holding steady pressure and the suddenly the pedal starts dropping. Then you have to release and press again to keep the car slowing down (pumping the brakes). Each time this happened to me, it was only on HOT days. The car would drive perfectly through the fall winter & spring.

[rocky]

basically a first braking event of the morning or evening after a day sitting there?

Seems to be a feature of our cars. Certainly my 05 had it for the longest time. However since I'm doing many more shorter journey's now than I used to, seems to happen less. Also pads are no longer OEM.