I have a 06 Volvo s40 (Manuel) and am hearing a thud near the front of the car. I have got the car to make the sound a few different ways. The first is starting off a little jumpy, also breaking abruptly. Now the breaking doesn’t have to be hard but hitting the break fast makes the sound. Last but not least going over bumps. My initial guess is the struts and maybe shock combination. To my ears it seems like the passenger side(front) but I guess it could be both sides. There are a few other ideas that are floating around other forums. Anyone have an experience with this? Or Any on a Volvo?
Not Volvo-specific, but common sources of thuds include:
Suspension bushings, particularly control arms
Loose battery brackets
Most thuds eventually evolve into clunks, which are easier to find.
I agree with Manolito that motor mounts (and/or transmission mounts) are a possible cause of this problem. The weight of the drivetrain can shift when you apply the brake, and this can cause the mounts to break.
Bad motor mounts tend to “thud” when you brake and thud even louder when you brake hard.
Bad bushings act like this too.
Noises can be subjective and in case a thud turns out to be a clunk it may not be a bad idea to check the ball joints; especially considering the part about going over bumps.
A ball joint giving up suddenly can be lethal to the occupants of the car.
I suspect a suspension problem of some sort. When you accelerate or brake it stresses the components of the suspension system, and if there’s any extra play in one of those parts, that movement can produce a thud sound.