After searching long and hard for a guide for fitting new discs, all that i really found was a few hints and tips...
So here it is, my in depth, picture heavy, guide for fitting front brake discs on an A3 8L.
First off, get your tools together;
- Grease/lube (i used copper grease)
- 7mm allen key socket
- 11/16 socket (or 17mm)
- Ratchet extention
- Metal bar
- Flat head screwdriver
- Cross head screwdriver
- 2xAxle stands
- G-Clamp/Vice/massive bicepts/piston rewind tool
- Wire brush
- Sharp knife / paint scraper
- Threadlock if you have it to hand
Once you have your tools together, make sure you have a garage or a nice bright english summers day and get cracking!
Jack up your Audi and get them sexy rims off, if you cant do this then please go no further! stay safe.. put it in gear, get your wheels chocked and get a axle stand under there.
Lock your wheels so the caliper is facing out, this will give you as much access to the calipers as possible. Firstly we need to spray your WD40 all over the bolts we will be removing, by the time you get to removing them hopefully the WD40 would of soaked in - 4 bolts in total, 2 with rubber covers, 2 big bolts that are probably rusted. (this pic shows 2 from the top, the other 2 are on the bottom of the caliper)
Then we need to take the calipers off, remove the rubber covers from the back of these bolts if you havent already and get them unscrewed using your 7mm allen key socket with ratchet extention. (i managed to snap my ratchet trying to undo the bigger bolts on the other side so i had to improvise)
Remove the clip on the front, pry one end off first using your flat head then the other.
Now grab your caliper and give it a good wiggle and yank, it might be a bit tight but keep at it and maybe get a mallet involved
Put it on your spare axle stand so its not hanging by its hose, pull the old pads off the disc and the caliper
According to Metromaster you dont have to do this next step, apparently you can just slide the disc out without removing the caliper carrier but if you cant wedge it out, carry on with this next step:
Now the hard bit, taking out the old seized bolts. I dont have access to a flamethrower or a windy gun so i had to take the brute strength route. You need to remove the bracket that holds the caliper, to do this there is 2 big bolts on the back of it that need to be taken out. Wire brush them down to try break the seal of rust between the bolt and the holder, also use a sharp knife of paint scraper to help. (bolts circled)
Spray loads more WD40 on them and get your 11/16 socket on the bolts, make sure the socket is properly hammered on so you arnt goint to round the bolts... Then what i did next was spectacular if i do say so myself... get a long bar (i used a leg from a gazeebo) and put it on the end of your ratchet, give it a nice hard tug clockwise (as if you were tightening it) hopefully that will break the seal of rust.. then pull your bar anticlockwise to loosen the bolt and hopefully it should come straight out. You could try using a hammer on your ratchet if you like instead but i think leverage works better.
With both of the bolts removed the bracket should just come off nicely. Remove the 1 cross head screw holding your disc in place and your disc should fall off too.
The next step is to unscrew the brake resevoir cap to allow any excess brake fluid to escape when you are clamping the pistons (tissue is to stop fluid going everywhere)..
Now because you are fitting new pads you will have to push the piston back into the caliper so they fit properly. You can get proper tools for doing this but i didnt have one to hand, the easiest tool that is usually around the garage somewhere is a G-clamp but again i couldnt find it so i had to improvise..
Clamp the piston in all the way and you will be left with this
Clean up the surface that the new disc will be sitting against on the hub, (Fingermouse's tip)
Then put your new disc on just as you took it off, put the little cross head in place, screw in the brake caliper carrier, make sure its nice and tight (metromaster advises using threadlock on these bolts). Now its time to lube up! get some grease in the places where the new pads will be moving (circled).. and slot in the pad on the outside of the disc
Grease up the other pad in the same place and click it into the piston. You now need to put the caliper back on, slot it in place and screw in the 2 x 7mm bolts. Make sure you lube these bolts! as your pads wear the caliper moves along these bolts, dont grease the threads, just the sides
Put the rubber caps back on the bolts, Put the spring on the front of the caliper back in place, check all the bolts are tight and everything is solid and your pretty much done!
Do the same on the other side, remember to screw your resevoir cap back on.
When you have your wheels back on and the jacks + axle stands out turn your car on and give your brake peddle a few pumps before you set off for a test drive
Please make sure you dont get any WD40/Grease or anything similar on your new discs or face of the pads!
I'm sorry if its a bit long or has too many pictures but i thought for someone who hasnt had any experience fitting discs / pads it would be of some use. Remember i am no professional, i am only going on points of information here and there that i have found, along with a bit of initiative of course and i wont be held responsible if anything goes wrong whilst you are doing YOUR car, you use these instructions at your own risk.
If there is anything i've missed or done wrong, let me know and i'll change it