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Hi, I have a 1999 Mazda Familia 1.5 litre 4 speed automatic (not tiptronic) sedan with 174,500kms on the clock. The transmission was serviced in 2010 at around 150,000kms according to the sticker on my windscreen.

I have had this car for two months now, and most of the time it is great.

However, I suspect there might be something wrong with the gearbox.

First of all, when the car is driving, the car changes gears very nicely all of the time, and never over or under-revs, and changes in a split second without delay. The overdrive works well aswell, and when cruising at 100km/hr it is usually at 2700-2800rpm.

One of the issues is, that on a about three-four occasions, the car can get quite "thumpy" at traffic lights when it is in drive and I am applying the brake pedal. The engine idle is fine though and there are no warning lights. When this happens, sometimes I flick it in neutral, and the severity of the thumping lessons.

One of my theory's is, as the brake pads are not fully smooth ( I know this from when I bought it and had it inspected two months ago), is that it ussually occurs when the car is warming up after being left out in cold/weather, and it could be the brake pads struggling to keep the car in place.
It also ussually (but not all the time), happens at traffic lights where there is a small incline, weather the car is struggling to hold its position or not, I dont know but the incline is so slight I doubt it.

And also, this only ever happened once, I was in a car park and I started the car up, but my foot on the brake, and put in in reverse, the beeping came on, however the car rolled foward. Because this happened about three times over when I tryed again, the brake pedal "hardened-up" untill I couldnt push it in, and it wouldnt stop the car when once again it still rolled foward when in reverse. I asked a car salesman from the car sales yard nearby if he could help, and he got it working fine strait away, and the car hasn't done it since.

I don't know if its anything to be worried about, but I would appreciate any advice/or information about potential problems you may know of from what I have explained.

Many thanks, Mitchell

It's hard to say whether or not there is actually a fault with this car, as you mention various symptoms, none of which would appear to be related.
The "thumping" you're refering to at idle when the car is in drive but reduces when you put the car into neutral, merely sounds like a harmonic vibration which can often occur with many cars, particularly in the warm up phase. To be honest, it doesn't sound like a problem - and highly unlikely to be related to the brake pads or automatic transmission. If anything, perhaps the car is idling a little slow, but again, I doubt that there's a problem.
The other problem you refer to sounds odd. The car shouldn't roll forward if the brakes are applied, but the pedal can harden up if you pump the pedal a few times.
So, the only thing that sounds like it needs attending to is the car rolling forward when the brakes are applied.
If the brakes are working fine at other times, I can't quite understand how this could occur, but brake failure is obviously a serious safety concern, so you need to get the brakes looked at.

Yeah...if its alright thats fine..so thanks for your help. Im new to owning a car..this is my first one and I would hate for something that was preventable to happen.
I might get my mechanic to look the brake lines in response to the other issue, but it has only happened once and the rest of the time the brakes work perfect..as after that happened I was on my way to paeroa and I have had to slam on the brakes and it brought me to a quick and abrupt stop. At some point, and I do plan to have this done soon..but these are for more or less comfort, it did come up in my initial inspection report that the front brake rotors needed machining and the bottom bushes of the front suspension arms were worn, but I never saw this as a major issue as it passed it vtnz warrant a week and a half before I bought it and in the inspection also, the brake lines and cylinders where all in good condition

From your descriptions, I don't think there's actually a mechanical issue, so it's probbly just a case of you getting used to the car.