August 6, 2012

My Garage - Passat W8 Passenger Side Output Shaft Seal Replacement

With 160,000 miles on my Passat W8, it was just a matter of time. A few hundred miles ago the front differential started leaking. It started slowly but continued to increase as the miles piled up so it was time to park it and consider the options. At first glance I thought it would be a big job but thanks to the many Passat/Audi owners out there on the forums it became clear it was something we could tackle in our garage. So, away we went online and got a couple of tools and a seal from my favorite VW parts supplier.

The mind bender however was how to disconnect the passenger side front axle with minimal disassembly of the front suspension and still find enough clearance to move it to the side and pull out the output shaft. The first afternoon I spent some time figuring out how to remove the axle bolts. It sounds easy right? First to come off and certainly the easy part of this job was removing the heat shield protecting the inner cv joint boot from the menacing heat irradiated by the W8 exhaust manifold/catalytic converter just a couple inches away.

Next to come off were the 6 bolts holding the axle to the output flange. Here the problem was how to get the necessary leverage to remove the bolts within the limited space available for the ratchet. My solution was to use a short extension. That in combination to the length (4 inches) of the 10 mm Triple Square socket, and my medium-sized ratchet provided the necessary length I needed to avoid the brake lines, etc. Most importantly, a small wood block I had laying around provided some support to keep the extension straight and giving me the much needed leverage to do this from below.

To get this done I placed the transmission in Neutral and rotated the axle until the bolt of interest lined up to where I placed the ratchet. Then, I held the brake rotor in place with a screwdriver inserted into the cooling vents.

Then it was a matter of removing a bolt, rotating the axle and repeat until all six bolts were out...

With the axle loosened it became clear that there was not enough clearance on either side (left or right) of the flange to place it anywhere far enough to be able to remove it. Hmmm... If I could only get a little bit more clearance... I have read about people removing one of the lower control arms to get the necessary clearance but that involves replacing a stretchbolt, something I wanted to avoid. I have also read about people detaching the lower strut bolt to allow the suspension to drop a bit. That seemed a bit less intrusive so that is where I went next.

Next to come off was the lower sway bar bolt. this is critical as the suspension will not drop on it's own while being held up by the sway bar. In hind sight, I should have done this while the car was still on the ground as otherwise the sway bar is loading the suspension making removal more of a challenge.

The next step turned out to be the MOST PAINFUL of the whole process. Removing the nut holding the lower end of the strut is the easy part, removing the bolt however is a whole other story! Pull the bolt out and you will confirm as many have reported in the past that it will collide with the rear control arm.  Who the heck designed this thing?? So much for the superiority of German engineering... The solution for me here was to CAREFULLY twist the lower front swing arm clockwise on the aging bushings using a vise grip (shielded with a piece of rubber) while pushing on the bolt from the front side with a small bolt. The bolt finally came out the other end after many tries and a whole lot of frustration. The by product? a few minor scars on both control arms as both the Vise Grip and the bolt left their mark. Next on the agenda was to let the suspension drop a bit. Right before trying to remove the bolt I had placed a small bottle jack below the steering knuckle to support it. After removing the bolt I lowered the jack only to discover the suspension didn't want to drop much lower than where it was already. I pushed down a little and got the strut to separate from the control arm but the suspension wasn't going anywhere. Hmmm... I moved the strut support closer to the streering knuckle (as shown below), moved the axle toward the front of the car, checked the clearance and...

I got the axle to swing forward and clear the flange! Having figured out that configuration worked, I moved on to figure out how to get the axle to stay out of the way. My solution? A bungee cord hung from the strut's spring.

 Victory at last! With the axle out of the way, the output flange finally became accessible.

Next on the agenda? Remove the oil fill plug just to make sure I could fill the differential at the end of the process. I initially tried with a ratchet attached directly to the hex bit but that did not work for me. There is space for the ratchet but not enough for the leverage I needed to loosen the plug. I ended up using a universal joint attached to two long extensions so that I could put some muscle behind it from outside the wheel well.

The final step was to remove that single T-40 torx screw that holds the flange. A plastic bowl placed below the differential caught the 75W90 lubricant that came out.

With the output flange removed the leaky seal was easily accessible.

With the flange out of the car it was a matter of carefully extracting the seal with a seal puller.

A couple of good pulls and the seal came out without a problem. The seal has a diameter of 3.5 inches.

A seal driver disc of 3.185 inches fit the seal perfectly.

The handle of my seal driver turned out to be long enough so that I could place a hammer in the space behind the steering knuckle and slowly tap the seal into place.  

With the seal installed, I drained the differential using a vacumm pump andI replaced the oil with fresh 75W90 Royal Purple oil.

So what tools did I end up using? Here are the most important ones for this project:
  • 18 mm socket and box wrench for the lower strut bolt.
  • 16 mm socket and box wrench for the lower sway bar link bolts.
  • 10 mm Triple Square bit for the inboard bolts connecting the axle to the output flange.
  • 6 mm Allen bit for the three heat shield bolts.
  • 8 mm Allen bit for the differential refill plug
  • T-40 Torx bit for the output flange screw.
  • Seal puller.
  • A seal driver with a 3.185 inches diameter.
  • Torque wrench (20 - 200 ft-lb range) .
  • Universal joint. 
Plus a variety of of other general tools (extensions, break bar, long screwdriver, rubber mallet, etc.).

Here are a the torque specifications I collected from various sources (use at your own discretion)
  • Axle bolts: 6x 10mm triple square bolts: 57 ft-lb (tighten in diagonal pattern then double check)
  • Lower strut bolt: 1x 18mm bolt/nut: 66 ft-lb
  • Sway bar end link: Lower connection to the sway bar; 2x 16mm bolt/nut: 74 ft-lb.

With everything buttoned up it was time to put the W8 back in service...


  1. Awesome... thank YOU! Just did this on my A6, and your writeup was spot on!!

    1. Glad to hear it was useful to you!