Does anyone know the size of the front wheel bearing bolt. It looks like 26mm but I cannot tell for sure. The only thing I know is that is that I do not have the correct size and I need to purchase a new one.

Also, from those of you with experience, will this nut come off with a breaker bar or will I need an impact wrench?

on my S4 1994 (Canadian) .

i don't know but usually if you buy the bearing kit for ( around 45 $ CAD ( around the same in us) .) .. you usually get the bolt

the bolt is pretty easy to get out with normal tools .. if you decide to change the bearing you'll need a press but the bolt i repeat is some sorta easy to get out doesn't seems to rust inside the threadings, so a good quality socket// allen (17mm if recall) , and an extention pipe to help force and you should be allright .. ;)

I have access to a friend's press but I am hoping I will not need it. I will probably use a slide hammer to remove the old bearing and then see how easy it is to press in in-place using clamps.

I want to get this done some night this week so I can drive the car to //SFest.

The torque on this is 150 ft-lbs plus 90 degrees which is likely in the neighborhood of 250 ft-lbs.

You will need a really good impact wrench or previously mentioned breaker bar.

Make sure you loosen and tighten this with the car on the ground.

Last time (on a 90) I used an impact wrench which I borrowed and it came off much easier than I expected. That time I thought I could have done it using my breaker bar.

My car originally had big ~27mm bolts, but the CV boot kit I installed last year came with newer style internal-head (i.e. Allen head) bolts. I don't know why but apparently that's the way newer Audis are.