vibration in 4wd
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vibration in 4wd
2003 4.6 M5OD 4WD... getting a slight vibration / whine in 4WD - it's wierd, only in 2nd gear, and it is like an oscillation: BUZZzzzz.....BUZZzzzzzz.......BUZZZZzzzzz
Only happens under load like up a hill, not when driving steady speed on level ground. It's minor, I can live with it, but is it an indication of a future problem? It sounds like what a mechanic once described as a "harmonic". Why only in 2nd?
Only happens under load like up a hill, not when driving steady speed on level ground. It's minor, I can live with it, but is it an indication of a future problem? It sounds like what a mechanic once described as a "harmonic". Why only in 2nd?
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Joined: Mar 2001
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From: So Cal
vibration in 4wd
Don't know your particular model, but in general if you are driving in 4WD, you will get more noise and rumble or vibration. You have almost twice as many parts moving around in 4WD and they add extra load to the engine.
As far as why only in second and uphill, probably due to the extra load making the engine work harder and the frequency of vibration is just right that you get extra noise from the harmonics.
Without getting back into my undergrad physics courses... Harmonics is essentially when the frequency of vibration being generated matches the harmonic frequency of your trucks various components. When you get to the right frequency, the vibrations are "tuned" and you will get more sound.
BTW if you double, triple etc the frequency around the harmonic vibration point, you will also get more sound.
Probably not a problem with your truck, unless the noise is more identifiable and localized.
Good Luck,
Jim Henderson
As far as why only in second and uphill, probably due to the extra load making the engine work harder and the frequency of vibration is just right that you get extra noise from the harmonics.
Without getting back into my undergrad physics courses... Harmonics is essentially when the frequency of vibration being generated matches the harmonic frequency of your trucks various components. When you get to the right frequency, the vibrations are "tuned" and you will get more sound.
BTW if you double, triple etc the frequency around the harmonic vibration point, you will also get more sound.
Probably not a problem with your truck, unless the noise is more identifiable and localized.
Good Luck,
Jim Henderson
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vibration in 4wd
thanks for the reply.
I thought it was a harmonic... because it only happens under those certain circumstances (matched rotation speeds of various parts).
I'm not going to worry about it, it is not very noticable. thanks for your input.
regards,
radar
p.s. I was going to make a joke about Kermit or other muppets but then I realized that was Jim Henson. you probably get a lot of that...
I thought it was a harmonic... because it only happens under those certain circumstances (matched rotation speeds of various parts).
I'm not going to worry about it, it is not very noticable. thanks for your input.
regards,
radar
p.s. I was going to make a joke about Kermit or other muppets but then I realized that was Jim Henson. you probably get a lot of that...
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Joined: Mar 2001
Posts: 4,968
Likes: 3
From: So Cal
vibration in 4wd
Yeah, main difference is that Henson is dead and he had a lot of money. I have more frogs than he did tho.
You could probably get the extra harmonic vibration in other gears if you could approximate the engine RPMs or Driveline RPMs, kind of depends where the harmic is coming from.
On some cars I have owned, different parts had different harmonics, so you could tell how fast you were going by the buzz.
Jim Henderson
You could probably get the extra harmonic vibration in other gears if you could approximate the engine RPMs or Driveline RPMs, kind of depends where the harmic is coming from.
On some cars I have owned, different parts had different harmonics, so you could tell how fast you were going by the buzz.
Jim Henderson
