Hub/Driveshaft bolt

[Toonmania]

I know on most passats like my last one had 17mm hex hub bolts but my "new to me" 2003 A6 C5 1.9tdi has 6 sided bolts (like a standard nut head) does anyone know what size these are?

[zollaf]

17mm hex bolts, new 6 sided bolts ?? which bolt exactly are you on about, as if its the one i think you mean, none of what you have said makes any sense.

[Toonmania]

Not talking about the wheels bolts, what I wrote makes perfect sense to me? what I said was 6 sided bolts (like a standard nut head) in otherwords external hex rather than the standard 17mm internal hex hub bolt, it's the hub/driveshaft bolt that goes into the cv joint i'm talking about

[zollaf]

ok, so thats a bigger head than 17mm. do you mean 27 mm, bi hex, thats 12 sided rather than 6 sided or single hex. the 6 sided ones are either 30 or 32mm iirc.

[Toonmania]

yeah it's the 6 sided one's they do look 30mm+ what's the advantage/disadvantage of these over the standard 17mm allen type bolt

[zollaf]

12 sides to grip on instead of 6 means you can apply a lot more torque without it rounding off. same goes with driveshafts. old landrovers for instance went for 1o spline shafts, then over to 24 spline which can hold a lot more torque. i suspect your a6 has had new bolts firtted that came in a cv boot kit. as far as i know all vag had 12 sided.

[Toonmania]

Well either way they are about to be changed again, I have a nearside inner joint knocking and the outer boot is starting to crack in the folds so I'll just swap the whole shaft over then completely refurb the original shafts that way I've always got spares to fit

[zollaf]

ah, right, you are on about the bolts that use a 17mm allen key type thing in them rather than a socket. a drain plug key of the right size fits them, 17mm. its just clicked when i bought my s4 into the garage and looked at mine. lol.. yeah, they are used just to annoy us.