suspension bolt/nut question
 

I just put in some H&R sport springs to the car but after driving it around a little I noticed that a nut came loose... and then the bolt started to make it's way out.

I want to replace it because I'm sure the shear force has started to mess with the threads, but I don't really know the dimensions of the bolt/nut. All the stuff online just says what the nut/bolt head size are and not the actual length. Are they M10? I'm also missing a couple of the bolts that attach the shock mount to the car. My questions are what are the dimensions of the bolts and is there anything I have to look for in particular so that I don't get the wrong kind?

Thanks for any help.

EDIT: it's a Quattro if that changes anything.

The bolt that attaches the shock to the mount is M12x1.5x85, part number N 102 412 01 and will cost you a few dollars from the dealership or online.

The bolt that attaches the mount to the body of the car is M12 and 24mm long, part number N 905 635 01.

Thanks so much man

So the Audi dealer didn't have the bolt for the shock and mount and no other auto parts places and shops had an M12 long enough. Ended up going to an industrial fastener company and got one 5mm shorter. It seems you could go as low as ~75mm and still have some extra room.

I hope you brought the old bolts to the shop and had the grade matched. For something as critical as the shock to mount bolt and mount to body bolts I would only run OEM hardware personally. You don't want that bolt breaking when going around a corner. Order the parts online if you have to, they'll be there in a few days.

^^^ Exactly. Also many of the bolts are torque to yield that simply means 1/4 turn before they break. These types of bolts require replacement after removal since they have stretched.

I'm fairly certain that the bolt he is referring to is not TTY. BaseDrifter was trying to point out that the hardness of the bolt purchased may be less than the original and eventually fail.