NVH Issue with 5-door?

I'm new to the list - just drove a 6S hatchback today, stick shift. Very nice! I loved the ride and handling, seating position, appearance, etc. But I did notice a noise, vibration, harshness (NVH) issue that I believe is caused by the hatch door. It's a slight booming in the cockpit when you go over bumps. I think the hatch flexes, creates a pressure wave that travels up to the driver's seat, and you can feel it in your eardrums more than hear it. I've noticed it in some other types of cars with a hatch too. Did anyone else notice this, or is it just me? Also, the fan was on high, so maybe that was pressurizing the cabin a little. I also drove the 4-door, but didn't notice this problem. Comments?

Randy B.

Not shure cause there were minor cosmedic changes in the models. was the rear hatch closed all the way? this car seems to know when a hatch/trunk is not closed but won't alert you till you double tap the lock button and no horn sounds.

I don't believe it's a suspension issue. It's in the design of the cabin or hatch door. It may just be that the cabin seals are too tight. I take it you haven't noticed it?

The booming noise over bumps on hatches is because of rear suspension noise. On a hatch, the cargo area is part of the passenger compartment. In a sedan, the trunk is behind the rear seats and all the rear suspension noise can be isolated in the trunk. This applies to all hatches & wagons, not a Mazda thing. To counter this, many manufacturers will add more sound deadening material on the hatch model. I do not know if Mazda did this for the Mazda6.

In addition, hatches also have less body torsional rigidity than an equivalent sedan because hatch lack the cross-member between the trunk and rear seats. Again, this applies to all manufacturers. To counter this, many manufacturers re-inforce the hatch door area and Mazda has done this for the Mazda6 hatch.

Like everything, there are advantages and drawbacks. The drawback for a hatch (compared to an equivalent sedan) are these items, but the gain, of course, is that one can put much more stuff into the cargo area of a hatch.

MUCH MUCH more stuff. I think the hatch almost has the same capacity as the Mazda 6 wagon with the seats down! (Rear seats that is)

Thanks - that sounds like a reasonable explanation. I'd really like to have the big cargo area of the 5-dr. Maybe I'll have to drive it back to back with the sedan and decide how much it will bother me.

Randy B.

I was right and edited it...damn

crossbow said:

MUCH MUCH more stuff. I think the hatch almost has the same capacity as the Mazda 6 wagon with the seats down! (Rear seats that is)

Click to expand...

Actually the hatch has almost the same total cabin/storage volume as the wagon, and both have alot more than the sedan. The wagon still has by far the most strictly cargo capacity with the back seats upright.

I haven't noticed this noise at all. A few years ago I owned a 1990 Mazda 626 hatch and didn't notice the noise on it either.

What I can tell you is that the hatch has stiffer more sporty suspension than the sedan (this is pointed out on Mazda's Canadian Web site). This may create a slightly more noisy ride, but wouldn't have anything to do with a pressure wave in the cabin.