[s-cars] Driveshaft alignment

[Vincent Frégeac]

First time I hear about the hose clamp trick. Sounds like something to keep
in mind in case of emergency. The problem is the unbalance may be half the
weight of the screw part and, in that case, you just replace a light spot by
a heavy spot. I think it would be better to ask a large machine shop where
they get their custom parts dynamically balanced when required and have your
shaft balanced by a shop with the proper tools. The balancing cost will
probably be cost effective compared to spend a whole week-end to replace a
light spot with a heavy spot.

In your case, if the alignment is not right, I would first go to an Audi
dealer to have the alignment checked with the proper Audi tool, then the
balancing shop, then I would call Force5, ask them to send a shaft ASAP
(express shipping plus car rental might be expensive but still much cheaper
than a new shaft) and deal with alignment only. As the shafts apparently
last close to 200Kmiles, a shaft around 100Kmiles should be enough (except
if you plan to keep your urS for _another_ 200Kmiles).


Vincent.

-----Message d'origine-----
De : 'JR' [mailto:audiurs4 at mailforce.net] 
Envoyé : 17 janvier 2007 14:35
À : Vincent Frégeac
Cc : s-car-list at audifans.com
Objet : Re: [s-cars] Driveshaft alignment

I hope it is the alignment.  I'm going to get back to the car this 
weekend.  If it's not how would you go about balancing the shaft or 
would you just get a new one?  I've heard of trial and error balancing 
with a hose clamp and the car on blocks.  You run the car with the 
wheels off the ground to check the balance.  Then if it's off you put a 
pair of hose clamps (the kind with the screw for tightening making one 
spot heavier).  Check again and if it's still off you rotate the clamps 
a little each time you check until you find it.  ever hear of this?  It 
sounds a little cheesy, but I'd rather at least try it than be without 
the car for another couple of weeks.  Has anyone tried this before?

Joel



Vincent Frégeac wrote:
> I used a 2x4 wood beam, four nails (two by half-shaft) and aligned the
nails
> level on the shaft before I removed it. Then rechecked the shaft after R&R
> to make sure all 4 nails touch the shaft when the nails are vertical
> (vertical alignment) and at the maximum angle the clearance of this area
> allows (horizontal alignment). The 2x4 doesn't even need to be straight as
> the reference is the nails' head, not the 2x4. A dark garage with a flash
> light facing you really helps to see if the nails are really in contact
with
> the shaft or only close to.
>
> As you have already removed the shaft, it can't be used as a reference
> anymore to put the nails. IIRC, the two half shafts have the same
diameter,
> which means the four nails should be on the same level. So you should be
> able to use any flat surface to check the nails height. Just check the
half
> shafts diameter first and if you find they are different, use washers
(plus
> spark plug gages for fine tuning) on a flat surface to adjust the position
> of the two nails for the larger half shaft. Last tip, it really helps if
the
> nails are not exactly perpendicular to the reference surface as the nails
> head will touch the shaft at one point only instead of the all head
surface,
> and it's easier to check one contact point with a flash light than a large
> contact surface.
>
> Beside, the Bentley talk only about alignment because we are supposed to
use
> only new, balanced and very profitable (for Audi) shafts. As you have R&R
> the shaft, the vibration may also be caused by an unbalanced shaft, which
> requires more than a piece of wood with few nails to diagnose and correct.

>
> There is still more chance the problem comes from the alignment so you
> should be good with this "best" home-made shaft alignement tool.
>
>
>
>
>
> Vincent.
>
> -----Message d'origine-----
> De : s-car-list-bounces at audifans.com
> [mailto:s-car-list-bounces at audifans.com] De la part de JR
> Envoyé : 16 janvier 2007 18:35
> À : s-car-list at audifans.com
> Objet : [s-cars] Driveshaft alignment
>
> OK so I replaced the center support bearing (bought one from 034 
> Motorsport)and repacked the dried out grease in the front CV joint on 
> the drive shaft.  I put everything back together the was and test 
> drive.  I get an awful vibration at about 20 MPH.  I understand this is 
> a symptom of the shaft not being exactly aligned.  The part is 
> new/different and who knows what else isn't exactly the same as it was 
> what with everything settled the way it was and layers of rust coming 
> off with each part.  I suppose I'll have to go buy an assortment of 
> washers and see if I can dial it in.  Anyone know what the best way of 
> aligning the shaft is without a specialized tool from Audi?
>
> Thanks,
>
> JR
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