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Driveshaft Replacement
 
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Pelican Technical Article:

Driveshaft 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 job of the driveshaft is to transmit the torque from the transmission and apply it to the rear differential. Being the engine/transmission assembly and the rear differential are rubber mounted and BMW uses a floating differential, there needs to be a little bit of flex in the driveshaft. BMW uses a two piece driveshaft with a center bearing supporting the middle of the shaft. This center bearing can wear out over time and you will feel a vibration and noise under severe acceleration and deceleration. Also the driveshaft uses a CV joint at the mounting point for the differential. CV joints can wear over time particularly with hard driving. You can extend the life of your driveshaft by repacking this CV joint with new special grease. In this tech article we will go over all of the steps to rebuild your driveshaft. A universal joint is also used in the driveshaft to allow the angle change at the rear differential. The U-joint bearings can dry out and cause a vibration when worn. If this is your issue, replace the rear section of the driveshaft.

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.

BMW uses a two piece driveshaft with a center bearing (purple arrow) supporting the middle of the shaft.
Figure 1

BMW uses a two piece driveshaft with a center bearing (purple arrow) supporting the middle of the shaft. This center bearing can wear out over time and you will feel a vibration and noise under severe acceleration and deceleration. Also the driveshaft uses a CV joint (yellow arrow) at the mounting point for the differential. CV joints can wear over time particularly with hard driving. You can extend the life of your driveshaft by repacking this CV joint with new special grease. A universal joint (red arrow) is also used in the driveshaft to allow the angle change at the rear differential. The U-joint bearings can dry out and cause a vibration when worn. If this is your issue, replace the rear section of the driveshaft.

Remove the entire exhaust system.
Figure 2

Remove the entire exhaust system. See our tech article on exhaust replacing. 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. See our tech article on driveshaft flex-disc replacing.

Working at the transmission, remove the three, 16mm driveshaft flex-disc fasteners (yellow arrows).
Figure 7

Working at the transmission, remove the three, 16mm driveshaft flex-disc fasteners (yellow arrows). The red arrows points to the wrench in the position to counterhold the locking nuts. Do not remove the flex-disc to transmission output flange fasteners (purple arrow), these can be left in place.

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 arrow points to the wrench in the position to counterhold the locking nuts.

Working at the driveshaft to differential connection, mark the orientation (red arrows) to help with reassembly later.
Figure 9

Working at the driveshaft to differential connection, mark the orientation (red arrows) to help with reassembly later.

Working at the driveshaft to differential connection, remove the six E12 external Torx fasteners (red arrow).
Figure 10

Working at the driveshaft to differential connection, remove the six E12 external Torx fasteners (red arrow).

Using a soft-faced hammer, tap the end of the driveshaft to break free the connection to the differential.
Figure 11

Using a soft-faced hammer, tap the end of the driveshaft to break free the connection to the differential. Support the driveshaft in case it falls.


Working at the driveshaft support bearing, remove the two 13mm fasteners (purple arrows).
Figure 12

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

Working at the driveshaft to differential connection, remove the driveshaft from the differential.
Figure 13

Working at the driveshaft to differential connection, remove the driveshaft from the differential.

Lever the driveshaft out of the flex-disc, remove the driveshaft from the vehicle trans (red arrow).
Figure 14

Lever the driveshaft out of the flex-disc, remove the driveshaft from the vehicle trans (red arrow).

Clean the sealing surface (purple arrow), as the new gasket needs a good surface to mount to.
Figure 15

Clean the sealing surface (purple arrow), as the new gasket needs a good surface to mount to. Clean the grease from the differential flange and replace it with new grease. Just add about a small amount. Most of this grease is from inside the CV-joint in the driveshaft, adding a little can help maintain lubrication over time. Install the driveshaft reverse of removal. Start with the connection at the transmission, then install and tighten the connection at the differential. Then install the center support bearing nuts finger tight. 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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Comments and Suggestions:
Wes Comments: Quick question, how can one tell whether to replace the drive shaft or only the flex disc? Are there visible signs other than the knocking during acceleration?
September 26, 2016
  Followup from the Pelican Staff: They have to inspected. Look for binding or looseness. - Nick at Pelican Parts  

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Page last updated: Fri 12/9/2016 03:02:15 AM