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Rear Drive Axle Replacement
 
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Pelican Technical Article:

Rear Drive Axle Replacement

Nick Czerula

Time:

4 hours4 hrs

Tab:

$300

Talent:

****

Tools:

Flathead screwdriver, prybar, 36mm 6 pt socket, E12 Torx socket

Applicable Models:

BMW E46 M3 Coupe/Conv (2001-06)
BMW Z4 Convertible (2003-08)
BMW Z4 Coupe (2006-08)

Parts Required:

Rear drive axle, drive axle bolts, Differential fluid

Hot Tip:

Replace bolts

Performance Gain:

Repair faulty drive axle

Complementary Modification:

Replace differential fluid

Drive axles transfer power from the differential to the wheels. The differential is solidly bolted to the rear subframe, whereas the wheels move up and down on the vehicle suspension. The drive axles therefore need to be equipped with flexible joints which allow a significant amount of bending and flexing by the drive axle. This is accomplished by equipping each drive axle with a constant velocity (or CV) joint at each end. The joint is filled with high temperature grease and sealed with a rubber boot.

These axle boots fail over time causing loss of grease in the CV joint. As a result an axle may become noisy or create a vibration. Removing a rear drive axle is not a difficult job, but plan to spend about half the day replacing it. Each inner CV joint attaches to the differential output flange using 6 special bolts. The outer CV joint includes a stub axle which fits through the wheel bearing hub and is secured to the hub with a 36mm nut. Both axles are obstructed by the exhaust and the rear sway bar. Both should be removed when replacing the drive axles.

You can replace the axle boots and clean and repack the CV joints with high temperature molybdenum grease. However, if the boot has been torn for a while, the damage has been done. At this point you are better off replacing the complete front drive axle.

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 include your vehicle information.

In this tech article, I will go over how to replace the rear drive axle on BMW Z4M vehicles. Other models are similar.

Drive axles transfer power from the differential to the wheels.
Figure 1

Drive axles transfer power from the differential to the wheels. The differential, is solidly bolted to the rear subframe, whereas the wheels move up and down on the vehicle suspension. The drive axles (red arrow) therefore need to be equipped with flexible joints which allow a significant amount of bending and flexing by the drive axle. This is accomplished by equipping each drive axle with a constant velocity (or CV) joint at each end. The joint is filled with high temperature grease and sealed with a rubber boot.

Remove the center cap on rear wheel of vehicle.
Figure 2

Remove the center cap on rear wheel of vehicle. Do this on the side of the vehicle you are replacing the axle on. Use a small flathead screwdriver to lever the center cap out of the wheel. Next you will loosen the drive axle nut (red arrow) through the hole in the wheel. Using a 36mm, six-point socket and a breaker bar, loosen the rear axle nut. Lift and support the rear of your vehicle. See our tech article on jacking up your vehicle and remove the drive wheel. If the nut is stuck, you may have to remove the wheel, then lever the folded portion of the nut away from the axle shaft end (red arrows). Once loose, remove the nut from the drive axle.

Place a hydraulic jack under trailing arm.
Figure 3

Place a hydraulic jack under trailing arm. Inset shows the placement of the jack pad, directly under the trailing arm (red arrow).

Remove rear shock 18mm mounting fastener (red arrow).
Figure 4

Remove rear shock 18mm mounting fastener (red arrow).

Remove rear coil spring (red arrow).
Figure 5

Remove rear coil spring (red arrow). See our tech article on rear coil spring replacement.

Next, you have to detach the rear sway bar (red arrow).
Figure 6

Next, you have to detach the rear sway bar (red arrow). Start by removing the two 6mm Allen bolts for the bushings (blue arrows). Left side shown, remove right side as well.

Then remove the 13mm mounting fasteners (red arrows) for the sway bar end link.
Figure 7

Then remove the 13mm mounting fasteners (red arrows) for the sway bar end link. Located at the top of the rear control arm.

Lower the sway bar with the end link attached (red arrow) down enough for drive axle to clear.
Figure 8

Lower the sway bar with the end link attached (red arrow) down enough for drive axle to clear.

Next you have to loosen six axle-mounting bolts (red arrows).
Figure 9

Next you have to loosen six axle-mounting bolts (red arrows). In this photo, three are out of sight behind the axle. You will need an E12 socket and a six-inch extension. Loosen the bolts until they come out of the axle flange in the differential. You do not have to remove the bolts from the axle. Rotate the axle to access all the bolts.

Pull the drive axle down and away from the rear differential.
Figure 10

Pull the drive axle down and away from the rear differential. If it is stuck, use a flathead screwdriver to detach it, or tap it with a soft-faced hammer.

Next, remove the drive axle from the wheel hub.
Figure 11

Next, remove the drive axle from the wheel hub. Use an axle remover (blue arrow) to push the axle out of the wheel bearing. Once loose, finish tapping it out using a brass punch (red arrow). As you drive the axle out of the wheel hub, guide it down and remove it from the vehicle. If you're replacing the drive axle with a new one, now is the time to remove the axle bolts and flat washers and transfer these parts over to the new axle. Install the axle in the reverse order of removing. If needed, use the axle puller / installer tool to draw the axle splines into the wheel bearing flange. Install the axle bolts on the differential and tighten. Then install the axle nut and tighten the axle nut. You will complete the final torque of the axle nut with the vehicle wheel on the ground. Then peen over the axle nut to secure it onto the axle shaft. I use a drift and a hammer to do this. Install the drive wheel and test drive the vehicle to confirm the repair is complete.

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Page last updated: Wed 12/7/2016 03:05:19 AM