Delrin drive shaft support

S. Jaworski syljay at optonline.net
Thu Feb 15 21:49:31 EST 2001


I took a look at the family album . . to see if the center bearing was
located after the U-joint. Its located in front of the U-joint. I think that
may pose a problem with a solid mounting(delrin) for the center bearing.

Here is my thinking on this:

1. The engine moves when it produces power.
2. This movement is a rotation around one of the side engine mounts.
3. That means that the attached differential will move up and down with the
torqueing.
4. The center driveshaft flange will move up and down, and so will the
attached driveshaft.
5. The driveshaft front CV joint will also move up and down. No, the cv
joint will not flex and "absorb" the movement since the axis of rotation is
not centered on the cv joint but on the engine mount.
6. The drive shaft moves . . . but the after end of this drive shaft is
locked into an immovable bearing. The solid mounting of the delrin bearing
support will not allow movement.
7. Something has to give . . . the delrin plastic . . at the point where the
bearing is pressed in most likely. It may not fail immediately, but with
repeated flexing you'll end up with stress fractures . . . it's just a
matter of time.

I guess the rubber bearing mounting has two functions . . 1. to reduce
vibration transmittal to the car body. 2. To allow for driveshaft flexing.

Is my analysis off-base?

I've re-built two driveshafts already, and I hate parting with $180 for a
center bearing when I may be able to put one together for much less. No, its
not that I'm cheap . . . I just have an attitude problem with overpriced
parts.     :-)

Syl
88 5000q
90 100q

----- Original Message -----
From: <JShadzi at aol.com>
To: <syljay at optonline.net>; <quattro at audifans.com>
Sent: Thursday, February 15, 2001 12:41 AM
Subject: Re: Delrin drive shaft support


>    Well, let me address your questions...first off, yes, delrin will
introduce a slight amount of noise and vibration, but not much as I can
attest to the prototype we did on a V8 quattro.  Infact, with the reduced
driveshaft slop, the car actually feels smoother, especially during throttle
transients.  Everyting is a compromise, use rubber and you are very isolated
from vibraiton, but then you have to put up with excess deflection and
reduced longevity, something the delrin solves in both respects.
>   As far as the Mercedes part, it should replace the the stock rubber
piece fine as long as the bracket is modified accordingly...I don't agree
with epoxy, it won't last a mile IMO.  It also sounds like a lot of work
IMO, what I am proposing will use the stock bracket, the delrin piece fits
inside the stock hollowed out bracket-no cutting or welding, a job that can
be accomplished by anyone using a drill and common hand tools.
>    I hope I answered your questions, the decision is yours to make  =)
> Javad
>
> In a message dated Wed, 14 Feb 2001 11:31:03 PM Eastern Standard Time, "S.
Jaworski" <syljay at optonline.net> writes:
>
> << Javad,
>
> Let me see if I understand what you are trying to do.
> 1. You want to replace the center bearing bracket rubber mount with a
Delrin
> part.
> 2. You fasten this Delrin part to the center bearing bracket . . . using
> nuts and bolts I assume? I assume you need to grind off the welds on the
old
> center bearing support?
> 3. Then you will install a readily available bearing to the center of this
> Delrin part. How will it be secured? Press fit?
> 4. Then you will press the bearing center onto the drive shaft . . I
assume
> you will need to remove that dust shield off the drive shaft. Same
procedure
> that Blau tells you to do when you buy their center bracket?
>
> Is my analysis correct?
>
> I think that the solid mounting will introduce some obvious noise into the
> passenger compartment . . no?
> Have you actually tested this assembly in a car and checked for noise?
>
>
>




More information about the quattro mailing list