a1base

Morning all,

I've decided to have a go at replacing the front pads and rotors on my A4 and the only place I've run into conflicting advice is whether I need a specialized piston retracting tool or not?

Anyone here got any advice for a first-time home mechanic?

Many thanks!


BASE

sparkyjack

The calipers are designed so that the push and twist caliper/piston tools needed for the rear brakes won't work on the fronts. There is a hole in the center of the outside of caliper in the correct place to insert a tool to shove the piston back.
I went to my FLAPS and bought a cheapo piston retractor tool took it apart and reassembled it around the caliper.

Take a look at you calipers and the tools it's pretty easy if you've done brakes with retractor tool.

gunsmoker

You don't need a special tool for the front pads.

Audirings4

+1

C-clamp will work fine.

Moviela

That is bad advice. The high precision of the cylinder and pistons requires a parallel jaw tool to reset the piston.

The specified tool is expensive, and hard to find. There are, however, inexpensive tools that consist of a bolt and two flat plates that will work fine.

If you cant the piston and scratch the cylinder, the caliper is a dead pork chop.

For the job make sure you have the specified brake fluid. Don't use what the parts Bob at Autozone tells you to use. It will have the wrong viscosity for the ABS system.

I also replace the flat head screws that hold the rotor to the hub. Make sure the surface of the hub to rotor is hospital clean. You will need a wire brush to make it clean and new.

When you push the piston back you can crack the bleed valve and discard the fluid in the caliper. Be sure to refill before pushing the brake pedal.

Take a picture of the brake pad warning indicator wiring routing. You must mount it exactly as shown in your picture.

When loading the pads a very thin coat of the special grease on the sliding "ways" will insure the pads won't drag in wet weather.

Has it been more than two years since you changed the brake fluid? Based on the build date for the car (on driver's door sticker) you must change it every two years to avoid corrosion in the system.

The anti-rattle spring goes on so easy if you place the wings in place with the tab out of the hole in the caliper. Then push the spring with the palm of your hand adding tension and the tab will fall in the hole so sweet even Tiger would smile.

Wear latex gloves and keep any hint of dirt or grease away from the pad surface and rotor. Use a bristle brush and brake cleaner (perch works best) to remove the loose stuff before you reassemble.

Use a torque wrench on all fasteners.

Take the car out and bed the pads. Look on Porterfield web page for the full process. You need a long lonely road.

Have fun.

Moviela

The piston retracting on the rear axel is done with a cable and a keyboard.

Gorillas that push the pistons back manually will ruin the EPB actuators and possibly brick the parking brake control module.

Audirings4

Tell me this oh wise one. IF the c-clamp is not parallel to piston when retracting it then what is it? I've even used my own hands on certain applications to retract the piston. It's not rocket science.

You also don't need to bleed the brakes or change the brake fluid.

You have a knack of making the easiest task seem tedious and overly complicated.

gunsmoker

Don't you guys get tired of re-posting the same opinion every time a newbie asks the same question and then argue with each other who's right and who's wrong? I can't count how many times I read about the planar honing of cylinders, retracting the brake pistons with or without tools, changing oil at short intervals and Blackstone analysis, the results of not changing the brake fluid every 2 years...

audiSfour

Well as you can tell, in forums there isn't always consensus on how to do things. I use a C-clamp and make sure it is positioned so that the piston is not being compressed unevenly. There are specialty tools out there though. I might pick one up soon just for the peace of mind.

Other than that, a socket set and a screwdriver should be enough for the pads. I've never done rotors though. A special tool is needed for the screw to remove it if I remember correctly.

a1base

Thanks for all your advice folks! Seems there're a couple of differing opinions out there for what to do!

I've had the wheel off and gotten a close look at the calipers now - From what I can see there are 2 sets of bolts. One is fine with a 13/16th socket which (I'm assuming) mounts the caliper to the caliper frame(? - the bit the caliper bolts into) that I can get to off without an issue. There are also another 2 largish triple square sockets (you've no idea how long it took me to identify those!) that require a special driver to undo - I'm not sure whether those are needed to remove the caliper, or whether they hold the caliper itself together? Anyone else seen those?

The only other thing I think I need is a size 8 torx bit which looks to hold the rotor itself onto the hub. That shouldn't be an issue - I've got dozens of them.


Several videos / posts I've seen also say you need to open the brake fluid reservoir cap before doing any work - does that sound right? Maybe to make retracting the piston easier?