difficulty: 3/5 (for both
back to 1000q: VW Passat TDI "how to" index (mk4)
The car shown is a TDI, your car may be slightly different. Do you have something to add to this article? Please post a comment in the myturbodiesel.com mk4 VW forum, also linked through the blue button above.
A very common problem on VW Passat and similar generation Audi A4, A6, and A8 is failure of the CV boots. The driveaxle has inner and outer constant velocity (CV) joints which are greased and covered by rubber boots. CV boots on these cars have a history of early failure. CV boots are considered a wear item but a normal lifespan is over 100,000 miles. The reason the boots fail so quickly on these models is because of a combination of suspension design and tight steering. As a result, the boots are flexed more than other models. One easy way to extend the life of the boots to a normal 100,000 mile lifespan is to not turn the steering wheel all the way to lock. This might mean making a slightly wider turn or an extra point in your k-turn but it will prevent early failure of the boots.
If you see grease sprayed on the inside of the wheel you know you have a CV boot failure even if you can't see it. A temporary repair would be wrapping the split with self sealing rubber tape and injecting some grease so that the car is driveable. This may prevent further damage if there isn't any clicking in the joint yet. If the CV joint isn't damaged than just clean the joint and regrease-replace the boot ASAP. If there's clicking, the joint is already bad. This is most likely noticed at slow speeds when parking because you normally don't turn the wheel that far to the side during normal driving.
If the joint is worn then a genuine VW or equivalent OEM supplier replacement joint on your existing axle is the best choice because it'll be more balanced and durable. GKN makes the CV joints for these VW-Audi models so I strongly suggest them. However, one you start pricing the OEM supplier CV joints you may find it more economical to buy an entire replacement axle from Raxles.com, an axle specialist. They use high quality replacement inner and outer joints on OEM cores (axle shaft). Aftermarket rebuilt axles from your local auto parts store are almost all very low quality because they're reground axles. Reground axles use worn out tooling and oversized bearings to grind away the hardened CV joints and are thenput onto cheap axle shafts.
The biggest reason to avoid cheap reground axles on the Passat -A4 is because they will often cause a noticeable vibration when in drive or reverse. This is usually felt when stopped at stoplight. This goes away once it's in neutral (at the stoplight) or when driving. It might not show up right away and it's not even something that many VW Audi dealership mechanics know because it's often misdiagnosed as bad motor mounts. Bad inner joints will cause knocking which is carried through the steering knuckle into the control arms, and into the body. It feels like you are sitting in a massage chair and is worse on the side that has the bad joint. One quick test for identifying the bad side is to feel the door panel on the suspected side for vibration. If you shift into neutral and the vibration stops, it's probably a bad axle.
Here is a video showing the play in
a bad aftermarket rebuilt axle
that was causing shaking at stoplights vs. a good used OEM axle. To
check it, firmly shake the inner joint by hand (with the engine and car not
running). In-out movement is normal because the halfshaft must move
up/down, in/out during normal driving, clunking or play is not.
Most early Audi A4, A6, and VW Passat used a 27mm hex head axle bolt. Most later cars (TDI) should use a 17mm allen head bolt. The actual difference is in the axle threads but most of the time, M16 threads used a 17mm allen bolt and M14 threads used a 27mm hex headbolt. This procedure shows both.
Automatic and manual transmission axles on these models are different. The driver and passenger side axles are also a different length.
I've seen pneumatic CV boot stretchers which supposedly lets you slip the new boot over the
joint instead of having to remove it. Unfortunately, they don't seem to work very well. Here's a review in this
forum review of the Schwaben tool.
CV boot kit for TDI
The boot kit should contain a new axle nut but if you need another one it's VW# 4b0 407 643 a
I recommend buying a rebuilt axle from Raxles.com. These use OEM quality joints and boots on OEM shafts. They also include the hex drive bit and triple square bits to help remove the axle.
17mm 1/2" drive hex bit for the axle nut, from metalnerd MNHB17
(non TDI or earlier VR6 may use a 27mm bolt instead)
torque wrench that goes up to at least 150-160 ft-lb (torque spec you will use is 140 ft-lb)
VW tool 1682 or generic CV boot clamp like the one shown below
Remove the hubcap or center cap. You may have to remove the wheel first to push the center cap out from the backside. See here for the location of the jack points on my 2005 Passat.
Once you have access to the 17mm allen hex axle bolt in the center of the hub, make sure the car is safe and secure with the weight of the car on the tires. Do not loosen the axle bolt with the car on jackstands - this is very dangerous. Loosen the axle bolt with a breaker bar with at least a 1/2" drive wrench/17mm allen bit while an assistant steps on the brakes to help counterhold. The weight of the car on the tires should do most of the counterholding. You can also use a 3/4" drive if available. My personal breaker bar is a 1/2" harbor freight tool that I bought for $9 - since I'm not a professional it wasn't worth it to buy a similar snap-on quality tool for $100+. However, you do want to use a quality socket because if it strips the bolt or nut, you'll have a very difficult day.
Pictured below is an allen wrench that you can use for removal only.
TDI should have the 17mm allen head bolt, other cars may have a 27mm
"regular" head hex bolt shown below. CAUTION: this assumes OEM
hardware. Aftermarket hardware could use a different style bolt
head. What matters is that the bolt threads are correct. The
replacement bolt must be torqued according to the bolt threads, not the bolt
Only after the axle bolt is loose, raise the car securely and rest it on jackstands. If you are doing both sides, make sure both sides are loose before raising the car. Make sure the car is safe and secure on jackstands before doing any further work. Again, do not try to loosen the axle bolts with the car on jack stands or on a lift! Remove the wheel.
Remove the 1x T25 torx screw holding the foam/plastic sound barrier to get more clearance (not all models may have these, the VW Passat TDI should). Remove the 3x 6mm allen bolts holding the heat shield around the passenger side axle.
Remove the axles by removing the 6x 10mm triple square bolts on the inner joint-flange. Put the lug bolts back in the rotor and have a helper step on the brake to counterhold the axle. You could also stick a screwdriver in the brake vents and turn the rotor until it's hitting the brake caliper. If the other side is on wood blocks (see 1000q: wood blocks for more details), you can also put it in park to counterhold the axle bolts. This is not the best way because it puts the stress on the transmission instead of the brakes.
On the driver's side, turn the steering wheel to the right for more access, on the pass side, turn the wheel to the left. Only turn the wheel about 3/4 of the way because if it's turned all the way the joint will be at too great of an angle. If you do, you can see the extreme angle that the boot is subjected to when the steering wheel is at full lock.
Pictured below is the passenger side.
Here's a picture with the bolts and foam barrier removed. This
is the passenger side with the heat shield. The driver's side has no heat
shield. You can see some of the 3x 6mm allen bolts holding the heat
Use the axle bolt threaded halfway to help push the axle out of the
spindle. It might be a little stuck from rust. Here you can also see
the allen bit head for the bolt. If you turned the wheel to the side you
can easily maneuver the inner end of the driveaxle up and around the transmission to
get it out. The service manual suggests removing suspension piece to get
the axle out because it tells you to remove the hub side first. This is a horrible idea because if you loosen the inner side first you can get the axle out without loosening any of the seized ball joints or pinch bolt.
Once the axles are removed, do not roll the car around with the weight on the
this could damage the front wheel bearings. Pass and driver side axles are
different lengths, don't switch them.
Here is a video showing most of these points. I also review the Raxles.com axle.
Clean the dirt off the joint and keep the axle clean to keep the new joint and grease clean. Pry the small clamp off with a screwdriver and cut off the boot. Below is a video showing my easy CV joint removal trick. The slide hammer was on loan from the local auto parts store. The traditional method of hitting the joint off is pretty futile on these axles unless you get lucky and the CV joint axis is aligned with the axle on your first hit. My method will save you a ton of time and effort.
If you choose to hit the joint off, make sure that as you hit it, it's not actually just moving the axle (because it's not securely held) or else it'll push off the inner CV boot's clamp on the other end. Use the old axle bolt to hold it straight while you knock it off. You can also hold it angled slightly towards the point where you hit it. This will keep the joint straight as you hit it. The joint must be straight to knock it off. Use a rubber mallet or a hammer with a wood block as padding. Don't hit directly on the metal with a metal hammer. Leaving the old boot bellow on the joint will help protect and pad it. You can also use blocks of wood to sandwich the axle bolt and hit the wood to knock off the joint. It will require some force to knock the joint past the outside lock clip.
Once the joint is off you'll see a plastic spacer and a dished waster. The outer diameter/wider sides of the dished washer and thrust washer
face each other. In other words, the wide sides should touch each other. The plastic spacer should point to the joint as shown in the video. Underneath is the inside clip. Remove this to get the new boot on. Your new CV boot kit should include a new one.
Once it's off, set the joint on a paper towel or clean surface. If your joint is OK I suggest not disassembling it. Just turn it and clean as much grease as possible off. Use your finger and a paper towel to clean the space underneath the bearing races too. Then flush any remaning grease out with brake cleaner.
If you believe there was dirt and water contamination and do disassemble the joint, note the cage position and inner section
position by using a metal scribe to make index marks against the housing. Tilt
the joint far to the side to remove the balls. Keep them in
order so they go back into the same spot. Once the balls are out, turn the inner cage 90o
against the outer cage and
jiggle/rotate it to pull it out. Then turn the outer cage 90o
against the housing to
pull it out. Note your index marks during assembly. There's only a
little bit of grease in there so again, I suggest not disassembling the joint unless you suspect damage. Here is a video showing disassembly:
Your TDI outer CV joint (98mm diameter axle) uses 120 grams of new grease. Put about 80 grams in the joint, 40 grams in the boot. If you have an axle that's 88mm diameter, put 40g in the joint and 50g in the boot.
The rest of installation is the reverse of removal. Here are some tips:
Remove the old outside lock clip, thrust washer, and dished washer and put on the new boot. Remember to slip on the clamps. Then put on the new clips/washer. The outer diameter/wider sides of the dished washer and thrust washer face each other. The plastic thrust washer's narrow end should touch the CV joint.
Press the CV joint onto the axle - a light knock with a mallet will easily press it on past the lock clip.
The service manual shows VW tool 1682 (cv boot clamp) and tightening the
lever's nut to 15 ft-lbs. I used a generic CV boot clamp to tighten it
until the clamp was tight and looked like the one that was removed.
The rest of installation is the reverse of removal.
When tightening the axle-transmission flange bolts, first tighten them in a diagonal pattern to about 10 ft-lbs. This ensures that the axle is flat. Then tighten them to a final torque of 57 ft-lb. After that I suggest double checking the torque. I also use some blue medium strength threadlocker to make sure they won't shake loose. Remember, torque specs assume clean threads - rusty bolts/threads will give a false torque reading. Since you have to use extensions, make sure the torque wrench is perpendicular to the bolt. Twisting or tilting the wrench will change the torque on the bolt. See 1000q: torque wrench FAQ for more details on using a torque wrench.
The torque on the (M16 thread) OEM 17mm allen axle bolt is 140 ft-lb + 180o turn. This is quite a bit but you already know that from when you removed the bolt. Use a torque wrench to get to 140 ft-lb first. Then you can use any 1/2" wrench for the final 180o turn. A 3/8" wrench could break. I used the cheap allen wrench shown above with a breaker bar.
If you have a 27mm bolt with M14 threads (obviously must also be on axle) instead of the M16 17mm allen bolt, torque is 85 ft-lb + 180o turn. Since VW changed over to the allen head bolts and TDI were built in 2004-2005, your TDI should have a 17mm allen head bolt with M16 threads. Again, aftermarket hardware could be slightly different so check your threads!
The axle bolt is only good for torquing to the final torque once! Do not reuse the old axle bolt! It's a stretch bolt and it's holding the wheel bearing and axle on!
6x 10mm triple square axle bolts: 57 ft-lb (tighten in diagonal pattern then
M16 threaded axle bolt (normally 17mm allen bolt but check): 140 ft-lb + 180o turn
M14 threaded axle bolt (normally 27mm hex head bolt but check) 85 ft-lb + 180o turn
wheel lug bolts: 89 ft-lb (tighten in star pattern twice then double check)
Inner joint replacement
Need to find out more about replacing a leaking CV boot or replacing the joint on your VW Passat? Please ask in the forums or google search below