So I found something odd under a car - ideas?
Discussion
I was helping someone change a starter on a Ford Galaxy (57 plate - TDCI) when I asked me what I thought this was.
I thought her was testing my amazingly limited mechanical knowledge - I had no idea, of course, and so but it transpires he had no idea either ;0
More pics here http://imgur.com/a/DNkSD
It's bolted to the shell crossmember behind the engine - NOTHING is connected to it, e.g. no power, hoses, pipes etc.
Made of steel - sounds hollow - 4 screws at the end open it but we didn't because things to do and homes to go to - but I'm still curious...
Ideas?
I thought her was testing my amazingly limited mechanical knowledge - I had no idea, of course, and so but it transpires he had no idea either ;0
More pics here http://imgur.com/a/DNkSD
It's bolted to the shell crossmember behind the engine - NOTHING is connected to it, e.g. no power, hoses, pipes etc.
Made of steel - sounds hollow - 4 screws at the end open it but we didn't because things to do and homes to go to - but I'm still curious...
Ideas?
hondafanatic said:
charltjr said:
They damp out vibrations at a certain range of frequencies that would otherwise cause noise/buzzing/ringing in other components or cause a sensation of vibration in the cabin.
Do all cars have them? 
charltjr said:
They damp out vibrations at a certain range of frequencies that would otherwise cause noise/buzzing/ringing in other components or cause a sensation of vibration in the cabin.
Essentially similar to what big buildings have at the very top if they know its going to be prone to tremors and wind vibrations. The mass-spring-damper arrangement inside moves independently to absorb the energy instead of it being transmitted to the body.I remember Renault F1 (Alonso era) had a mass damper in the nose of the car to control its vibrations when attacking the curbing on corners. Helped to keep the wheels planted on the ground instead of bouncing. I think it got banned.
Mass dampers are very common devices.
robinessex said:
hondafanatic said:
charltjr said:
They damp out vibrations at a certain range of frequencies that would otherwise cause noise/buzzing/ringing in other components or cause a sensation of vibration in the cabin.
Do all cars have them? Otispunkmeyer said:
charltjr said:
They damp out vibrations at a certain range of frequencies that would otherwise cause noise/buzzing/ringing in other components or cause a sensation of vibration in the cabin.
Essentially similar to what big buildings have at the very top if they know its going to be prone to tremors and wind vibrations. The mass-spring-damper arrangement inside moves independently to absorb the energy instead of it being transmitted to the body.I remember Renault F1 (Alonso era) had a mass damper in the nose of the car to control its vibrations when attacking the curbing on corners. Helped to keep the wheels planted on the ground instead of bouncing. I think it got banned.
Mass dampers are very common devices.
ks! But lets not wander off the subject of the postingI recall a story I heard, that in the early days of the Vauxhall Viva, occupants were complaining of feeling travel sick. It was eventually noticed that owners of cars fitted with a sun roof didn’t. Turned out to be a low frequency vibration of the roof panel, between 4Hz-7Hz. Such frequencies can’t be heard, but can be felt, particularly by your ears hearing mechanism. Hence the travel sickness result. The roof panel resonance was fixed by gluing thin plywood panels to it with a semi non-setting adhesive that provided lots of damping. If you want to experience a similar event, try gradually opening a window at motorway speeds, you’ll eventually feel/hear a deep drumming sound, quite uncomfortable. Basically the car has become a Helmholtz resonator, and you are sitting in it!
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