Very interesting problem with M-5 E 39

Fernando · 6th March 2001, 19:57

First of all hello everybody.I have a question for the peolpe that run more than 240 Km/h..
When i go from 230 240 Km/h to 250 km?h my both mirrow begin to shake.This is normal??There are others M-5 with the same problem??
I Went to dealer to see if it was ok and there aren't no problem.

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Fernando
00'M-5 Jet Black/Black interior/steel
BMW 01'R 1150 GS yellow

[This message has been edited by Fernando (edited 08 March 2001).]

DrKevM5 · 6th March 2001, 20:10

I think that is where you just reach the edge of the shockwave. Chuck Yeager had the same problem...

Fernando · 6th March 2001, 20:21

DrKevM5 belive me it's true..i don't why this happen..

Quote:

Originally posted by DrKevM5:
I think that is where you just reach the edge of the shockwave. Chuck Yeager had the same problem...

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Fernando
00'M-5 Jet Black/Black interior/steel
BMW 01'R 1150 GS yellow

[This message has been edited by Fernando (edited 08 March 2001).]

Pop Dog · 6th March 2001, 20:29

How bad was the problem? Where thy shaking very badly? It could be that you're going top speed, or was it a rough road.

Fernando · 6th March 2001, 20:34

I was not at top speed..it begine to shake a lot when i was at 230 Km/h in any conditions..i went at 292 KM/H in the speedometer,but not in real gps.My M-5 don't have top speed limit

Quote:

Originally posted by Pop Dog:
How bad was the problem? Where thy shaking very badly? It could be that you're going top speed, or was it a rough road.

DrKevM5 · 6th March 2001, 20:42

I'm very sorry Fernando, I couldn't resist it.

I do know some of us have had a problem with the folding mirrors, specifically if you had them folded and someone tried to unfold them. This could have easily screwed up the mechanism and caused loosening.

PhilSeastrand · 6th March 2001, 20:58

I would have to believe there is a problem. The rated top speed for the car is 155 MPH and it should hold together at that speed. If you try to move the mirrors by hand is there any play in them?

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Phil

01 M5 Silverstone/Silverstone

Mozieman · 6th March 2001, 22:29

Fernando,

Voce e Brasileiro? Nao sou Brasileiro mas eu morava la vinte anos atras..Nao melembro Bmw's em Brasil quando eu esteve la..

ijam · 6th March 2001, 23:48

do they stop shaking once you go a bit faster?

it could be that this particular speed is right to set up harmonic resonance with the mirrors, causing them to shake (feel free to correct my physics you guys if I'm getting it wrong)

harmonic resonance causes two motions to combine to amplify each other - just about every system has a specific set of frequencies which will do this... (thats really woolly and poor, but I haven't done physics for a loooong time)

it might also be a combination of a set speed and a particular road surface. either way if it is this you will find going 10kph faster or slower will greatly reduce the shaking

a good example of this was the Tahoma Narrows bridge, which collapsed in 1942 (?) due to wind of a particular velocity rushing accross it and the resultant motion amplifying and amplifying itself until it collapsed - also some of the transmitters on Alexander Palace in London transmit on a frequency harmonic to the human body and are therefore very dangerous to be near!

we used to have a Renault 12 estate, and the car would nearly shake itself apart at 60-62mph but be fine at all other speeds...

ciao

Ian

M5Laser · 7th March 2001, 00:06

From the high school physics I learned last year, I think ijam is right. I remember my physics teacher saying that every car has a speed that it will experience turbulence at. I know our old van used to get it at about 120 km/hr. This summer I think I determined our Volvo will do it for a sec about 160 km/hr.
But as you speed up It goes away. Its just the speed of the air flowing over the body of the car at that point. A certain point will cause turbulence.
I'm sure that someone with a little bit better physics background can probably add a lot to that.
Although I remember he was telling us about a story about when he was driving a VW Jetta on the Autobahn (spelt that wrong?) a few years ago. He said he was driving with the car at its top speed and then "a pack of 5 BMW's flew by me like I wasn't moving. Wow those cars are amazing."
I got a kick out of that! Maybe was a group from here...