[s-cars] Rebuilt driveshaft

[Paul Gailus]

A proper alignment doesn't necessarily result in having the centerlines of the front and rear sections of the driveshaft in line with each other. This will only happen if the differential pinion shaft is also in line with the rear driveshaft (i.e., their centerlines are at 0 degrees to each other). So you might want to check on this last angle, since it's not easily adjusted.
Something like this may work:
http://www.stu-offroad.com/axle/pinion/pinion-1.htm

As I understand it, the centerline of the front driveshaft and the centerline of the differential pinion shaft should be made parallel. In other words, the angles at the front U-joint and the rear U-joint should be equal and opposite. The variation of the rotation rate from the front and rear U-joints will then be compensated to a large extent (that's why the front and rear U-joint yokes are usually rotated 90 degrees on-axis from eachother). 

I've also heard that having exact 0 degree angles at U-joints is not preferred. It's better to have a very small angle (even 1 degree) so that the needle bearings move a little and don't get frozen up over time.

Paul

-----Original Message-----
>From: Wayne Dohnal <wd42 at hevanet.com>
>Sent: May 14, 2008 6:07 PM
>To: Fred Munro <munrof at sympatico.ca>, S-car list <s-car-list at audifans.com>
>Subject: Re: [s-cars] Rebuilt driveshaft
>
>For the vertical alignment of the center bearing, I took a 2x6, notched it 
>to clear the center bearing, and drove four 3-inch drywall screws, one for 
>each end of each driveshaft half, into it about a half inch.  I then made 
>sure the screw heads were in a perfect straight line and held screw heads up 
>to the driveshaft to check if it was straight vertically.   That was the 
>easy part.
>
>For the horizontal alignment I ran a tight string under the driveshaft 
>centered under the drive flanges on each end, then checked the horizintal 
>alignment at the center bearing.  This was very difficult to do while lying 
>flat on the floor.  I used a level to make sure I was shooting the position 
>reference straight up from the string.  I think I got it pretty close in the 
>end but spent a couple of hours doing it.
>
>All of this just happens automatically with the Audi alignment fixture. 
>Sigh.
>
>Wayne Dohnal
>1994 S4
>
>
>----- Original Message ----- 
>From: "Fred Munro" <munrof at sympatico.ca>
>To: "Wayne Dohnal" <wd42 at hevanet.com>; "S-car list" 
><s-car-list at audifans.com>
>Sent: Wednesday, May 14, 2008 3:36 PM
>Subject: RE: [s-cars] Rebuilt driveshaft
>
>
>> Wayne;
>>
>> How did you align the driveshaft when you re-installed it?
>>
>> Fred Munro
>> '97 S6
>>
>
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