I did a forum search, but was unable to find a thread with pics on how to remove/re-fit seats in an A3. As I was swapping my half leather for full leather today, I thought I'd take some pics and write a guide. I hope people will find this useful.
Please excuse the crappy phone pics. I didn't realise they were so bad until I'd finished and got them on the computer. Anyway, here goes.
10mm Spline Bit and Socket Set for front seat removal
T30 Torx Bit set for rear seat removal
11/16" (17mm will fit too) Socket and wrench for seat belt bolt removal/replacement
Here are my original seats. I removed my rears first and then got a mate to help me take the fronts out later in the morning. The front seats aren't massively heavy, but a bit awkward to get out on your own without damaging something.
For the purposes of this guide, I'll do it in order and I'd advise removing the fronts first as it will give you more room to do the rears.
First job is to remove the bolts that hold the front seats in place. Slide the seats either fully front or back to reveal the spline bolts which you need to undo as shown below. Slide the seats the other way to undo the other two bolts. There are two at the front and two at the rear.
Once you have undone all the bots, tilt the seat back to reveal the cables underneath. The cables are in a cover which will need to be removed. There are two plastic hooks under the yellow circles. To remove, get your fingers under the area circled in red and pull up towards the roof. It will pop out and then you can slide the cover off freeing the hooks.
With the cover off, you can get at the cables. Disconnect everything. The amount of cables will vary depending on driver or passenger or heated etc. You'll also need to open the cable tidy in the far left of the picture. It's a bit fiddly, but it's just pushing in a very small clip.
Once you've freed the cables, carefully pull the seat out of the car. You have to do it at an angle and I would suggest removing the head rests as it makes it a lot easier to get the seat out.
To fit the new seats, simply reverse the process. Connect the cables, re-fit the cable cover. Align the runners to the holes and bolt down. Re-fit head rests and ensure it all slides around and adjust correctly.
Front seats in
First off, you need to remove the bench seat. I found this to be the hardest part as it feels like something will break and unfortunately for me it did. Should be a cheap fix though.
You can see in the picture below that the leather and carpet are seperate parts and the bench part should lift up. It requires quite a bit of force, but start from one side of the seat and lift up and move along bit by bit from one side to the other. The bench part of the seat is held at the front by two metal rings that fit inside two plastic clips.
The seat belt clip circled in red will need to be removed later.
The metal rings on the underside of the bench fit inside grey plastic clips in the sub-frame that should just pop out. Unfortunately one of mine got stuck and pulled the clip out of the sub-frame which damaged it. I then had a hell of job trying to seperate the clip from the ring. Heopfully you won't have this issue as the other side popped off with no damage.
Once you have released the front, push the whole bench towards to back of the car and you will feel it release the from the hooks holding it in place. The whole bench should then come out.
Fold the seats down and open the boot. Take out the boot liner so that you can see the black clip in the picture.
Finger hurty time! There are clips holding it on roughly where I've circled in red, so get your fingers in the holes marked in green and pull the sides apart with a little force to release it.
You will then see a small torx screw circled in red which will need to be undone in order to remove the metal plate circled in blue.
Once removed, you will see the two plastics discs which hold the two seats together and allow them to fold down as circled in red. In the picture I have already removed the smaller of the two rear seats so only one disc is shown. From here you will be able to lift one side of the seat out. The other side is fixed by a small pole that goes inside the opposite side of the seats. You should be able to slide the seat off of this pole and lift it out of the car.
To remove the other larger rear seat, you will first need to remove the seat belt shown earlier that is secured to the sub-frame via a bolt.
Lift up the felt protection to expose the bolt. You will need the socket set to undo that bolt and once freed, you can lift the whole seat out of the car.
Job done! To re-fit the new/relacement seats, simply reverse the instructions above. Get the seat belt lined up and bolt it down first and the rest should be easy.
If anyone has any questions. Please feel free to PM me.