This article is one in a series that have been released in conjunction with Wayne's new book, 101 Performance Projects for Your BMW 3 Series. The book contains 272 pages of full color projects detailing everything from performance mods to timing the camshafts. With more than 650+ full-color glossy photos accompanying extensive step-by-step procedures, this book is required reading in any 3 Series owner's collection. The book was released in August 2006, and is available for ordering now. See The Official Book Website for more details.
One of the most common sets of suspension items to replace or service on the 3 Series are the Â"constant velocity,Â" or CV, joints that connect the wheels to the transmission. These bearings, packed in grease, get a tremendous amount of wear through the years and tend to wear out after about 100,000 miles. One of the clear signs the joints need replacing is a distinct Â"clunk, clunk, clunkÂ" sound coming from the rear axle when the car is in motion.
In some cases, the boots that cover and protect the CV joints will be torn and need replacing. The procedure for replacing the boots is very similar to the procedure for replacing the entire joint. Install new boots each time you install a new CV joint.
For both the E30 and E36 cars, BMW sells only a complete, replaceable axle. The new axle contains both the inner and outer CV joints, as well as the boots that cover and protect them. The inner E30 CV joints are no longer available to purchase separately.
First, jack up the car (see our Tech Article on jacking up your BMW) and remove the road wheels. Then, pry off the dust cover cap on the wheel hub if your car has one in place (Photo 1). Now, knock out the back of the center hubcap of the wheel, remount the wheel to the car, and then lower the car. With the car in gear and the emergency brake on, use a long breaker bar to loosen up the drive shaft flange collar nut. This nut is tightened to more than 250 N-m (184 ft-lbs), so it will take quite a bit of force to loosen it up. Lift the car up again and remove the wheel once more.
Next, start removing the bolts from the inner CV joint (see Photo 2). YouÂ'll need a properly sized Torx socket set for this task. Warning: You must have the correct tool for this task, or you might strip the CV bolts. If you do strip the bolts, the only way to remove them is to grind them off, which is not a fun task.
To access the CV bolts, rotate the wheel until you can clearly get your Torx socket wrench on the bolts. Then, pull the emergency brake and place the transmission into first gear. This will allow you to loosen the bolts without having the axle spin. When you have removed all the bolts you can from this angle, release the brake, take the car out of gear, and rotate the wheel until you can reach the next set of bolts. When all of the bolts are removed, suspend the end of the drive axle with some rope or wire.
Once you have the CV bolts disconnected, itÂ's time to remove the axle. Disconnect the brake caliper and brake rotor assembly, and hang the caliper out of the way. Place your floor jack under the rear trailing arm to support it. Remove the lower shock mount bolt. Now, lower the rear trailing arm so you have enough clearance to remove the stub axle from the hub. If you cannot pull the axle out of the hub, you may need an axle-pulling tool to push the center of the axle out of the hub.
Remove the axle and take it to your workbench. The inner CV joint is held onto the axle by a large circlip, which is located under the large rear dust cap. The outer CV joint is not removable. If you wish to replace the CV joint boot on the outer joint, you must remove the inner joint first. Remove the inner circlip, release the boot clip, and the joint should come right off. ItÂ's generally a really bad sign if large balls from the bearing start falling out. ThatÂ's a clear indicator you need to replace the joint. If you reuse the joint, carefully place it in a plastic bag to avoid getting any dirt or grime in it. Even a grain of sand in the CV joint can cause it to wear out prematurely. Carefully inspect both CV joints for any wear prior to installing them back into the car.
Once you remove the joint, replacing the boots should be easy. Simply disconnect the small clips that hold the boot to the shaft and slide it off. The new boots are installed in a reverse manner. Rotate the joint through its entire motion before tightening the small, inner boot clampÂ--you donÂ't want it to be too tight.
When installing new CV joints, pack them with plenty of CV-joint grease before you install them. Also place plenty of grease in and around the boot. Move the joint in and out as you insert the grease to ensure itÂ's well lubricated, as new CV joints do not come pre-greased. When ready, place the new boot on the axle, and then place the CV joint on the axle. Reattach the circlip so the joint is attached to the axle. Reinstalling the axle is essentially the reverse of the removal process. Use a new driveshaft flange collar nut and retainer plate when you mate the axle back with the hub. Deform the nut and/or retaining plate after the nut is tightened.
Once you have the entire assembly back together, take the car out for a drive and check the rear for noises. All should be smooth and quiet, and the boots should no longer leak.
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The driveshaft flange collar nut is hidden by a metal cap (green arrow). Pry this cap off after you remove the wheel to gain access to the nut (red arrow). Pop out the center hubcap to your road wheel, remount the wheel to the car, and lower the car so the wheel will be held steady as you loosen the driveshaft flange collar nut. When reinstalling the axle, deform the retaining nut around the stub axle splines (purple arrows).
The four CV joints are located in the rear of the car, attached to the transmission flanges and the stub axles on the trailing arms. Replace the joints in pairsÂ--either both of the inside ones or both of the axles. Chances are, if one of the joints is showing signs of wear and deterioration, the other three will not be far behind. The inset photo shows the inner CV joint dust cover that must be pried off in order to access the retaining circlip underneath. The yellow arrows show four of the six Torx bolts that attach the axle to the rear differential.
This complete axle has a new nut and retainer plate, an inner CV joint, and a CV boot kit for an E30 3 Series. On the 3 Series cars, the outer CV joint is not available separately but must be purchased as a complete axle, because the joint is integrated into the stub axle and cannot be separated. If the boots are damaged and leaking, you should replace them, because dirt and debris can find their way inside. Apply the Loctite 2701 that comes with the CV boot kit to the CV bolts just prior to installation.