Outer CV boot replacement or how to remove and replace the driveaxle
on VW Passat
mk4, also works on Audi A4 A6
difficulty: 3/5 (for both
sides)
back to 1000q: VW Passat TDI "how to" index (mk4)
Introduction
This article shows how to remove the drive axle aka. half shafts or driveaxles,
and replace the CV boots on your VW Passat. This procedure should also
apply to the Audi A4 or A6 of the same generation. 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 few outer CV boots have split earlier than expected. CV boots are considered a wear item but a normal lifespan is well over 100,000 miles. If you see grease sprayed on the inside of the wheel you know you have a CV boot crack or split even if you can't see it. A temporary repair would be wrapping the split with self sealing rubber tape to prevent further damage. Your local auto parts store probably carries or at least knows of this repair tape. You could also put on a slip over CV boot repair but a good repair should include a joint inspection with a new boot. If the CV joint isn't pitted and worn then you can just put on a new boot.
If the joint is worn then a genuine VW or equivalent quality replacement joint on your existing axle is the best choice because it'll be more balanced. Some aftermarket rebuilt axles from your local auto parts store tend to be very low quality. These typically come with a lifetime warranty axle and new boots/rebuilt joints but I've noticed the exterior of cheap rebuilt axles will rust much faster than OEM axles and may not come well balanced. Raxles.com has a good reputation for rebuilding axles on these cars.
The big reason to avoid cheap rebuilds on the Passat with automatic
transmission is because they will usually cause a noticeable vibration when in
drive or reverse when stopped at stoplight that goes away
once it's in neutral (at the stoplight) or during driving. It might not show up right away and it's
not something that many VW Audi dealership mechanics would know. A common
misdiagnosis is 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. Here is a video showing the play in
a bad aftermarket rebuilt axle
which was causing a 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.
If you hear clicking when driving with the wheel turned far left or right then it could be bad CV joints. Vibration at idle when in drive vs. neutral could also be excess play in the CV joint. This vibration can be felt even when the car is not moving, it's because there is excess play in the joint which is transmitted to the transmission.
Early Audi A4, A6, and VW Passat used a 27mm axle bolt. Most later cars (TDI) should use a 17mm allen head bolt. This procedure shows both.
Parts
CV boot kit for TDI from worldimpex
w/genuine parts , w/generic
parts (contact the vendor if you need a non-TDI boot, these links are for
the TDI axle)
The boot kit should contain a new axle nut but if you need another one it's
VW# 4b0 407 643 a
Tools
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
Procedure
Remove the hubcap or center cap. You may have to remove the wheel to push the center cap out from the backside.
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 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.
Pictured below is a cheap allen wrench for removal, you'll need a 1/2"
drive hex allen bit socket and torque wrench for tightening it.
TDI should have the 17mm allen head bolt, other cars may have a 27mm
"regular" head hex bolt shown below.
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.
Pictured below is the passenger side.
Here is 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 also see some of the 6mm allen bolts holding the heat
shield.
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, I do not suggest this.
Once the axles are removed, do not roll the car around with the weight on the
front since
this could damage the front wheel bearings. Pass and driver side axles are
different lengths, don't switch them.
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. Leave the large clamp and the last
bellows on the large/outer end of the boot to protect it while you knock off the
joint. (I thought of leaving the large clamp on after this pic was taken).
Pry off the sharp inside clip holding the inner side of the CV joint. Note the
position of the washers. 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
and the narrow side of the thrust washer should touch the joint. You can't
remove them until after the joint is off.
There are a few ways to get the CV joint off. One is to knock it off while clamping the axle in a vise. Put the axle in a vise to securely hold it while you knock the CV joint off the axle. The joint is held by the outside lock c-clip, you have to push the joint past the lock clip to release it.
Make sure that as you hit the joint that 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.
Here is a trick to remove the joint but it requires the inner joint to be
removed. If you have some way to hold the CV joint while you pull the axle
straight off it would do the same thing.
Once it's off, set the joint on a paper towel or clean surface. I suggest not disassembling the joint, 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.
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. There's also a paint mark on one of the inner cage teeth, pictured above. I suggest lining up your index marks on the housing and cage with the paint mark on the gear-like inner cage (visible in the above picture). This way it's reassembled in the original orientation.
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 balls and joint unless there is damage. You could also just remove a single ball to check it's condition.
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 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.
Use some brake or carb cleaner on a rag to wipe clean the sealing surfaces of the CV joint. When the boot is almost in place, put a thin bead of grease resistant gasket maker around the edges and slip the boot over it.
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. Smear
away any excess gasket maker.
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 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 instead of the 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.
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!
Torque specs:
6x 10mm triple square axle bolts: 57 ft-lb (tighten in diagonal pattern then
double check)
17mm allen axle bolt: 140 ft-lb + 180o
turn
(if you have a 27mm hex head bolt) 85 ft-lb + 180o turn
wheel lug bolts: 89 ft-lb (tighten in star pattern twice then double check)
Do you know something that should be added to this article? Post your comments in the myturbodiesel.com forums