Quick question about driveshaft harmonics...

supraguy@aol

supraguy@aol

Well-Known Member
Dec 30, 2005
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Atlanta
Hey guys-

I have read in a few different posts, that aftermarket single-piece driveshafts- particularly aluminum ones- tend to have a droning vibration to them. I figure that this makes sense, because it's basically a hollow metal pipe, and prolly transmits and amplifies the noises from the engine, tranny and even noises coming up from the road/ halfshafts/diff. If anyone wants to correct this part, please do.

Anyway, I was wondering if it's possible to simply coat the shaft- either inside or outside, with a deadening material...perhaps a rubberized undercoat treatment or something like that, that will perhaps absorb some if not all of the resonances. I've been kinda mulling this over, and thought i'd ask here if anyone has either done this, and if so, what material might help this issue, or if it didn't help at all when attempted.

Toss your thoughts/ opinions out here.

PS- If you have a single piece DS, and haven't had any resonance/ vibration problems, please throw that out here too!
:)
 
supraguy@aol

supraguy@aol

Well-Known Member
Dec 30, 2005
4,234
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Crap!- MODS- please move this to general section- didn't realize I was shopping when this question hit me!
 
tekdeus

tekdeus

Pronounced Tek-DAY-us
Jan 23, 2006
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www.bitrontech.com
During driving, mine is quiet. It just makes a hollow "ping" noise when you bump it in 1st or reverse. I was thinking of putting some very small pieces of dynamatt on there, since it doesn't take much to deaden the tone of the noise. but maybe the spray-on stuff would be better?
 
M

Mr. Sinister

Member
Aug 30, 2005
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The one I got from the Eric Ekberg GB years ago has had no noise or vibration issues up to 80 mph. Haven't driven faster than that to see if there are any issues above that speed.
 
supraguy@aol

supraguy@aol

Well-Known Member
Dec 30, 2005
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Umm.....What kind of power was this guy putting into that shaft? I'm only intending to go to ~350-400hp when I install mine...
PS- I've already bought a driveshaft loop for mine, so hopefully something like that won't be able to happen to me.... I hope....
 
Poodles

Poodles

I play with fire
Jul 22, 2006
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it's not the power, but the rotational speed gets to critica and causes the harmonics to destroy the shaft..

it's kinda like taking a piece of string and spinning it between your fingers, it ends up bowing out and bows out farther the faster it spins...
 
supraguy@aol

supraguy@aol

Well-Known Member
Dec 30, 2005
4,234
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Atlanta
Oh yeah- I see what you mean now. It's not a twisting force, but an inertia or centrifugal force. Never thought of that at all.
 
I

IJ.

Grumpy Old Man
Mar 30, 2005
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Universal joints don't rotate in circles they spin in figure 8's and at a certain length/speed this becomes "Critical"

the stronger built the shaft the longer it will last at this speed/load, aluminium in use work hardens and eventually will fail with stress fractures so while it dampens nicely it's NOT the best chioce of material to build a shaft from let alone a single piece.
 
CRE

CRE

7M-GE + MAFT Pro + T = :D
Oct 24, 2005
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tekdeus said:
That's crazy. At least it's comforting to know that this has not happened to a MK3 yet, I'm assuming.
Click to expand...


Sorry, there have been a few reports of aluminum one piece drive shafts failing... still haven't seen anyone post with issues with a steel one. (Knowing my luck, that's going to be me in a month.)
 
CRE

CRE

7M-GE + MAFT Pro + T = :D
Oct 24, 2005
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I was just referring to Tek's comment about it happening with a MKIII.


I'd be interested to know the length and gauge of that one.
 
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