some brake questions - ceramic rotors? pad replacement?

[kismetcapitan]

forgive my ignorance as I've just started doing my own work on my car (I've worked on my bikes myself for years). I'm about to do my brake pads and if I understand correctly, I just need to pop out the retaining pins (two per caliper), remove old pads, insert new pads, and done?

What about pushing the pistons back to accommodate the thickness of the new pads? Any handy tricks? Any other things to pay attention to? should the backs of the pads be greased with copper grease? or anything weird with the brake pad wear sensor connection?

In doing a bit of research I just discovered that our front brake calipers are the same ones that are used on the R8. Which leads to the question - if it's the same brake setup, can R8 ceramic rotors be installed as a direct fit onto out RS6 hubs?

TIA!

[hahnmgh63]

Probably the rotor would work. Also, the B8 RS5 wave rotors work too (fronts only, rears are a different brake hub). The Ceramic/Carbon rotors are expensive and usually need to be paired with the correct brake pads (also expensive). Need to double check that the front Calipers are the same with the Ceramic brake option (rotors were increased from 365mm to 380mm), they may be different. There was a kit from Europe for Ceramics for the front of the C5 RS5 using all OEM Audi components but it was over $10k.
Edit: Just found the R8/RS5 Ceramic rotors for just over $5k a piece. I'll stick to metal rotors I think.

[kday]

If it's been a while since your pads were changed, especially if you're in a corrosion-prone area, you may find that it's impossible to remove the pins. In that case you can remove the calipers and replace the pads from the other direction, with a bit of fiddling.

I don't remember exactly what I have done to compress the pistons but it was probably just a C clamp and a block of wood or two.

[kismetcapitan]

that's good to know. going in from the bottom with the caliper removed is how I have to change the pads on my Brembos on my bikes. There's a fair bit of fiddling but nothing difficult with the pistons retracted. Hopefully (if the pins are stubborn) it'll just be a larger version of the same process.

[kismetcapitan]

popping the retaining pins was a piece of cake. getting the outer pads, also easy - just a tap from under, and the pads come flying out the top. compressing the pistons - easy. Only thing you need to watch for is the brake fluid reservoir; it'll start to overflow with the pistons retracted.

But what wasn't so easy was the brake pad sensor connection - it's clipped on something fierce. I ended up hammering and chiseling them out. Thankfully, the part that's clipped to the upright is the connector coming from the pad, so breaking that is no big deal.

The inner pads - not so easy. I'm sitting here with 7 of 8 front pads installed, and I just can't get that last pad (inner upper pad) to come out. The pistons are fully retracted, it's wiggling easily side to side, I've used brake cleaner to clear out gunk, and there's nothing mechanical holding it in. It's as if there's the world's stickiest goop on the bottom pad support keeping it from coming out. I can't find a decent angle to tap the pad out from underneath, and I'm about to lose my marbles...especially since the other 7 pads were so easy.

any tricks in getting the inner pads out, without removing the caliper? I've loaned out my impact wrench and anyways I don't have the right socket (looks like a 22mm?) Can't drive anywhere without finishing the job, for obvious reasons....

[hahnmgh63]

On the Audi pads you don't re-use the brake wear sensors like on a Porsche. The new pads should come with the sensor embedded or else you will have to clip the old sensor wires and plug it in so it doesn't set off the warning.

[kismetcapitan]

yep, and I finally realized you insert the plug into the clip sideways, then rotate it. not knowing that ended up taking me longer than the entire pad replacement.

From what I understand, the sensor works on a simple principle of completing a circuit. Once worn down to where it contacts the rotor, the rotor bridges the two leads and the circuit is complete and the ECU detects it. taking an old male connector with the wires snipped off and plugged into the female harness end, will mean you'll never be bothered by a low brake pad warning. You'll also have to check your pads visually however lol. I opted to have fully functional pad sensors.

btw the stickiest grease known to man was holding the stubborn pads in. A squirt of degreaser and letting it sit for about 5 minutes was all it took, I could then just pluck them out with my fingers.