Vibration - No its not my wheels
06-24-2011, 06:13 AM
#11
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The number of wheels/tires that have passed balance and even perfunctory RFB and still been *visibly* bent (watch with a straight-edge at high speed spin) is staggering.
I vote flat spot ont he inside rim of a wheel. Or 2.
Also could be driveshaft.
G
I vote flat spot ont he inside rim of a wheel. Or 2.
Also could be driveshaft.
G
06-24-2011, 06:18 AM
#12
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OK. So if the wheels are really, really round, then its likely not a wheel/hub/axle issue at all. Is it really through the suspension? Or is it the motor? Motor mount? Driveshaft bearing?
Good luck, these cars are very vibration prone. But for me it has always been the wheels and/or tires.
G
Good luck, these cars are very vibration prone. But for me it has always been the wheels and/or tires.
G
06-24-2011, 07:08 AM
#13
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I have a set of 16" OEM sport wheels with my winter tires, 17" OEM BBS wheels with all seasons on it and a set of 18" Miro's with my summer tires on it. I have done road force, wheel eccentricity and tire pull lateral force measurments with success on the Hunter. On the Snap on laser balancer I can only do lateral runout but the laser is able to pick up fine imperfections and runouts, also with success. The tires where also force matched to the wheels. There is not much more information and work I can do to make these sets any straighter than they are. That is why I have ruled out the wheels/tires in the problem.
06-24-2011, 07:13 AM
#14
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Could also be bent flange on a hub.
Did you dial in the rim after it was on the car to check the run out?
I still stick by my CV joint diagnostic.
Generally a motor mount or whatever will vibrate at a certain frequency and that is it. If the speed stays steady (and rpm too) then there are cyclic vibrations chances are are 99.7% not going to be in the mounts.
Did you dial in the rim after it was on the car to check the run out?
I still stick by my CV joint diagnostic.
Generally a motor mount or whatever will vibrate at a certain frequency and that is it. If the speed stays steady (and rpm too) then there are cyclic vibrations chances are are 99.7% not going to be in the mounts.
I will use a runout dial this weekend, thank you as I didnt think of that.
Is there any driveshaft assemblies greater than the other? Should I pick up an OEM or are the aftermarkets just as good?
06-24-2011, 03:09 PM
#15
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I have used after market drive shaft assemblies for both my A6 and A4. At 138$ for the A6 and 90$ for the A4, it was almost as cheap as two boots, but none of the cleanup time or mess. The way to go IMHO.
06-27-2011, 02:52 PM
#17
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Funnny... I have the exact same issues with 2002 S8
I also had this with C5 4.2. I did everything except new driveshaft. three sets of tires and wheels, front driveshafts, Hunter Roadforce balancing,rotors, etc. -finally sold it. Now I have an 02 S8, with the "in the front seat" vibration... steering wheel is OK; rear seat is OK.
So next week I am trying a new Driveshaft. The really weird thing is that sometimes the vibration sort-of goes away... like at 75mph with no load on the drive train. But if decelerating (engine slowing me down), or accelerating, the vibration is definitely there! - hence the drive-shaft theory.
So next week I am trying a new Driveshaft. The really weird thing is that sometimes the vibration sort-of goes away... like at 75mph with no load on the drive train. But if decelerating (engine slowing me down), or accelerating, the vibration is definitely there! - hence the drive-shaft theory.
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