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Driveshaft Flex-Disc Replacement
 
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Pelican Technical Article:

Driveshaft Flex-Disc Replacement

Nick Czerula

Time:

3 hours3 hrs

Tab:

$200

Talent:

*****

Tools:

Set of sockets 10mm, 16mm, 16mm wrench, floor jack, pry bar

Applicable Models:

BMW Z4 Convertible (2003-06)
BMW Z4 Coupe (2006)

Parts Required:

Driveshaft flex-disc, Driveshaft flex-disc fasteners, exhaust gaskets and hardware

Hot Tip:

Work with a cool engine and allow exhaust to cool before beginning

Performance Gain:

Smooth drivetrain

Complementary Modification:

Replace bolts for flex-disc

In BMW Z4 models with rear-wheel drive, the driveshaft connects the transmission output shaft at the rear of the transmission to the rear differential.

The transmission is mounted to the chassis and the rear differential is mounted to the rear subframe. The rubber mounts that attach engine-transmission and subframe to the chassis have some give so that the drivetrain unit and the differential move slightly in relation to each other; the rear driveshaft has to have some flex to allow for this movement. The flex in the driveshaft is provided by the flex-disc between the front of the driveshaft and the rear of the transmission or transfer case output shaft.

The flex disc is made of solid rubber and wears out over time. You may experience a drivetrain vibration or shimmy. If so, inspect your driveshaft flex-disc. It should be free from distortion, cracks and tears, and have no missing pieces. If you find any of these problems, replace the driveshaft flex-disc and mounting fasteners. To access the driveshaft flex-disc, you have to remove the exhaust system. When replacing, at the minimum, replace the self-locking nuts that attach the driveshaft flex-disc. I prefer to replace the bolts too. The driveshaft flex-disc is also referred to as the Giubo.

In this tech article, I will show you how to replace the flex-disc on BMW Z4M models, other Z4 models are similar.

Keep in mind that when your car was serviced before, parts may have been replaced with different size fasteners used in the replacement. The sizes of the nuts and bolts we give may be different from what you have, so be prepared with different size sockets and wrenches.

Protect your eyes, hands and body from fluids, dust and debris while working on your vehicle. If working with the electrical system, disconnect the battery before beginning. Always catch fluids in appropriate containers and properly dispose of any fluid waste. Recycle parts, packaging and fluids when possible. Do not work on your vehicle if you feel the task is beyond your ability.

Vehicle models change and evolve as they grow older, so the vehicle shown in our illustrations may vary slightly from yours. If something seems different, let us know and share your info to help other users. Questions or want to add to the article? Leave a comment below. When leaving a comment, please leave your vehicle information.

Raise and support the rear of the vehicle on jack stands. See our tech article on jacking up your vehicle.

Remove the underbody splash shields. See our tech article on engine splash shield removing.

The flex-disc (red arrow) is just out of sight and is tucked above and forward of the transmission cross member.
Figure 1

The flex-disc (red arrow) is just out of sight and is tucked above and forward of the transmission cross member. Inspect it for dry rot (purple arrow) periodically.

With the exhaust removed, remove the two 10mm nuts (red arrows) on the heat shield to the right of the transmission mount bracket (purple arrow).
Figure 2

With the exhaust removed, remove the two 10mm nuts (red arrows) on the heat shield to the right of the transmission mount bracket (purple arrow).

Working at the rear of the exhaust heat shield (red arrow), remove the two 8mm mounting fasteners (purple arrows).
Figure 3

Working at the rear of the exhaust heat shield (red arrow), remove the two 8mm mounting fasteners (purple arrows).

Next, remove the 10mm nut (red arrow) on the heat shield to the left of the transmission mount bracket.
Figure 4

Next, remove the 10mm nut (red arrow) on the heat shield to the left of the transmission mount bracket.

Working on the left side of the body, remove the two 10mm nuts (red arrows) on the heat shield.
Figure 5

Working on the left side of the body, remove the two 10mm nuts (red arrows) on the heat shield. Then remove the 8mm fastener (purple arrow), remove this fastener on the right side as well. Support the heat shield as you remove the final fastener.

Remove the exhaust heat shield toward the rear of the vehicle (red arrow).
Figure 6

Remove the exhaust heat shield toward the rear of the vehicle (red arrow). Store it in a safe place, do not bend it when removing. Then remove the driveshaft flex-disc.

Working at the transmission, remove the six, 16mm driveshaft flex-disc fasteners (purple arrow).
Figure 7

Working at the transmission, remove the six, 16mm driveshaft flex-disc fasteners (purple arrow). The red arrows points to the wrench in the position to counterhold the locking nuts.

Keep the transmission in neutral so you can rotate the driveshaft, remove the six, 16mm driveshaft flex-disc fasteners (red arrow).
Figure 8

Keep the transmission in neutral so you can rotate the driveshaft, remove the six, 16mm driveshaft flex-disc fasteners (red arrow). The purple arrows points to the wrench in the position to counterhold the locking nuts.

Working at the driveshaft support bearing, remove the two 13mm fasteners (purple arrows).
Figure 9

Working at the driveshaft support bearing, remove the two 13mm fasteners (purple arrows). Mark the location of the support bracket for reassembly (red arrows).

Lever the driveshaft out of the flex-disc (red arrow).
Figure 10

Lever the driveshaft out of the flex-disc (red arrow).

Then move the driveshaft to the side and remove the flex-disc from the vehicle (red arrow).
Figure 11

Then move the driveshaft to the side and remove the flex-disc from the vehicle (red arrow). Remove the flex-disc from the driveshaft. Be sure to replace the nuts for the flex-disc. They are self-locking and should not be reused. Install the new driveshaft flex-disc onto the driveshaft and install the fasteners finger tight. The purple arrows point to the orientation indicator on the flex-disc. Before removing, note the position and be sure to install the replacement flex-disc with arrows showing in the same direction. The arrows should point toward the mounting flanges. Then install the center support bearing nuts finger tight. Then install the driveshaft flex-disc to the transmission and tighten the fasteners. Then tighten the driveshaft flex-disc to the driveshaft fasteners. Once the flex-disc is tight, preload the center bearing to about 1mm toward the transmission and tighten the nuts. Finally, install any items you removed to improve access. Once tight, reassemble the heat shields and the exhaust system.

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Page last updated: Fri 12/2/2016 03:01:58 AM