Rear Diff. Movement revisited...
07-07-2003, 10:49 AM
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Rear Diff. Movement revisited...
Recently I <a href="https://forums.audiworld.com/s4/msgs/1275125.phtml" target="_blank">posted</a> about the thumping from the rear differential when launching the car. I had a chance to get under the car and check things out.
Here is the forward mounting arm for the rear differential (the part that is causing the problem):
<img src="http://pictureposter.audiworld.com/6924/112_1265.jpg">
The metal portion to the right of the picture is sandwiched between the underbody and the subframe brace and isn't allowed to move. It is connected to the arm only by rubber. This is obviously to dampen movement and isolate the rear diff from the body.
Here is the problem with that part:
<img src="http://pictureposter.audiworld.com/6924/112_1269.jpg">
The flimsy rubber around the thicker supporting rubber 'X' has ripped allowing too much movement of the rear differential. This allows the differential to hit the underbody as shown here:
<img src="http://pictureposter.audiworld.com/6924/112_1277r.jpg">
My temporary solution was to cut some polyurethane shock bushings in half and wedge them in to eliminate that movement.
<img src="http://pictureposter.audiworld.com/6924/112_1283.jpg">
This worked perfectly, but it did lead to some noticeable vibration & noise between 1800 and 2800 RPMs while on the throttle. I've since taken those bushings out and am going to see about getting that part replaced. According to the dealership parts dept., it retails for around $130 (p/n: 8A0 599 133 B).
-Dave Pramanik
Here is the forward mounting arm for the rear differential (the part that is causing the problem):
<img src="http://pictureposter.audiworld.com/6924/112_1265.jpg">
The metal portion to the right of the picture is sandwiched between the underbody and the subframe brace and isn't allowed to move. It is connected to the arm only by rubber. This is obviously to dampen movement and isolate the rear diff from the body.
Here is the problem with that part:
<img src="http://pictureposter.audiworld.com/6924/112_1269.jpg">
The flimsy rubber around the thicker supporting rubber 'X' has ripped allowing too much movement of the rear differential. This allows the differential to hit the underbody as shown here:
<img src="http://pictureposter.audiworld.com/6924/112_1277r.jpg">
My temporary solution was to cut some polyurethane shock bushings in half and wedge them in to eliminate that movement.
<img src="http://pictureposter.audiworld.com/6924/112_1283.jpg">
This worked perfectly, but it did lead to some noticeable vibration & noise between 1800 and 2800 RPMs while on the throttle. I've since taken those bushings out and am going to see about getting that part replaced. According to the dealership parts dept., it retails for around $130 (p/n: 8A0 599 133 B).
-Dave Pramanik
07-07-2003, 11:17 AM
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I doubt its been updated...
There wasn't any mention of the part being superceeded when I called the dealership. I'm still under warranty (but not for much longer), so I'm going to try and get them to replace it for me.
-Dave Pramanik
-Dave Pramanik
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07-07-2003, 11:24 AM
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A friend of mine mentioned some liquid spray that...
hardens to a polyurethane consistency. Might be able to spray some of that into the area above and below the ripped rubber to reinforce it. Not sure how well it would work in this case, though.
-Dave Pramanik
-Dave Pramanik
