Brake pad change question
 

I am getting ready to change the front pads on my 2018 S5 Convertible and was wondering about whether or not anyone opens the bleeder screw while retracting the pistons. I’ve never done that on any car in 40 years of doing brakes. I didn’t do it when I changed the rears a few months ago. I was watching a couple YouTube videos to make sure I had the proper sockets (had to buy an M10 triple square socket) and I saw two people said to open the bleeder because you could damage the one way ABS pump.

So my question is, how many of you do it and how many don’t? I’m hoping I don’t risk having to bleed the system after that.

I do not open the bleeder screw, after changing brakes on 4 Audi's no issues at all.

The workshop manual by Audi says nothing about messing with the bleeder screw when resetting the pistons. Never done it, never had a problem. It does say make sure the fluid level in the reservoir is not already at the max line. If so, there's no place for the fluid to back up into as the piston is pushed back; you have to extract some fluid from the reservoir first to make room.

I’ve never done it either and this is the first time I’ve ever heard anyone suggest doing it. I always check the reservoir to make sure it won’t overflow.

This guy works at an Audi dealer. He doesn't loosen the bleeder. He has many videos on many items including brakes.

as stated, make sure you are not near the top of the reservoir or when you push the pistons back in you will volcano brake fluid in the engine bay which is a total mess. ask me how I know. HAHA.

I’ve never had that problem either…knock on wood

AS a customer, not a mechanic, what's the benefit of not trimming the rotors? Or rather what's the downside for going to a small repair shop and asking for a rotor trim?

Unless doingthe work yourself, cost of resurfacing a rotor might exceed that of a new one; also depends on how much thickness remains as there might be possible issues if rotor becomes thinner than rated minimum before the new replacement pads become due for replacement themselves. YMWV.

This “replace not resurface” rotors has been a German vehicle “feature” for quite a few years. I know Mercedes and BMW have the same requirement. Personally - IMHO, YMMV — it’s about Added Dealer Profit (ADP) via the Service Department. Unless you are an enthusiast like many of our members are, most people with high-end German vehicles just take their cars back to the selling dealer for service needs.

I was quoted something over $1,000 for replacing my rear pads, rotors & whatever else is required. If I went to an indie shop and specc’d the same type of non-OEM parts, but not higher-end parts, I would guess I would trim between $250 & $300 off the dealers price.

And, again, this is my opinion (based on doing some research) and it may not be exact based on your area & labor rates.

— John