blakbelt

Hi Everyone,

I am replacing my wheel bearing and CV Axle while I am at it on my 2009 A4. Never done this before, and the first step is causing me some concern. The axle bolt that is on the car appears to be a 19MM hex head, but the wheel bearing that I purchased came with a 17MM hex head. This difference cause me some concern so I did not break lose the 19MM on the axle yet because I was concerned that maybe I bought the wrong wheel hub. Is it normal for the aftermarket parts to come with different size heads, or should I assume I have the wrong assembly?

blakbelt

Definitely got the wrong hub assembly.

Pat Schaedler

Interestingly enough I have this issue with my b8.5 allroad. The new axle bolt is 17mm (and that is the factory size as well), however the oem bolt either by material loss from rust or some other reason needs a 19mm hex to get it out. Makes no sense but 17mm is the factory size on these cars.

SMac770

The OEM bolt on the B8 platform is definitely a 19mm inner hex, not a 17mm.
All B8 A4, A5, Q5, at least for the US, use the same bolt, 8E0407643A.
You might find another M16x1.5x72 bolt on your car with a 17mm inner hex head, but it's not the bolt Audi AG assembled the vehicle with.

bo2006

same issue, my left side was 19, right size 17...