Non P-car Brake Question

Innov8 · Innov8's Garage

OK. I've got a question about the rear brakes on my Audi S4 and I am turning to the best online community for solid answers. The Audi boards just are great but this board has ALWAYS given me solid advice.

I'm replacing the pads and rotors and the S4 has floating (lucas) calipers on the rear with an intergrated parking brake. When replacing the rotors and pads, you need to use a fitted retraction tool on the caliper piston that rotates the piston as it pushes it back into the caliper. Unfortunately, a busy schedule forced this job to wait and the pads were quite thin on the driver side... I am afraid that I have a stuck caliper.

I have tried:
Soaking the piston with PB Blaster
Opening the bleeder valve
Disconnecting the battery and re-connecting so that the ABS switch releases (per Audi forum)
I AM able to rotate the piston with channel lock pliers (carefully) but while it rotates, it does not retract.

I am calling on my p-car brothers to come to the rescue. I am hoping to avoid having the car on jack stands for the 2 days it will take to get a new caliper for Audi (plus $265).

Anyway, as always, your advice is appreciated. Thank you, Patrick

peppy · 04-21-2008, 09:55 AM

On my VW I opened the bleeder valve to let off some of the pressure.

There is a special tool for this, but I do not have one. You need quite a bit of pressure to screw the piston back in.
I have a home-made tool that goes in the two holes and you drive it with a ratchet, you can also buy a cheep one at an auto parts store.

Also you could tap the piston with a hammer VERY LIGHTLY with a wood block to protect the piston as you try to screw it in.

Innov8 · Innov8's Garage

Thanks Peppy. I appreciate your input AND our hosts letting me post a question non- porsche related.

I got to retract...finally ! It took an unexpected (and unbelievable) amount of effort but this is how it happened:
- removed the rotor
- re-assembled the caliper mounting bracket and the caliper so I could hold the caliper still while using two hands on the retraction tool
- opened the bleeder valve and master cylinder
- using was the channel-lock pliers on the end of the retraction tool so that I could be maximum leverage...and my weight.
- this requires patience and endurance!

It all took a while but it eventually went back. Either I am a 200lb wimp or this thing was truly stuck. Has anyone else ever experienced this problem? I assume that I will need to replace the rotors on the next 20k miles as the cylinders are sure to be stuck again.

Anyway, I just test drove the car and all seems to work fine. -Patrick

cashman · 04-21-2008, 06:20 PM

Next time, go to AutoZone. They will let you "rent" the correct tool to do this. You give them a $30 deposit and you get it back when you return the tool. I just did this to my VW Passat. Worked fine and saved me the headache you just went through.
Mark

peppy · 04-23-2008, 06:22 AM

Mark,

From the mechanic that told me how to do this, it is a common problem.

911quest · 04-23-2008, 06:38 AM

This is basically the tool you need to do it without any problems.

http://www.dieselgeek.com/servlet/Detail?no=313

Watch out for the newer VW's, Audi with the electric parking brake, you will need a scan tool to get the caliper piston pushed back in

aj88cab · aj88cab's Garage

Patrick

This might not be the issue with your caliper and retractor tool, but if you have purchased one of the relatively inexpensive retractor tools that are sold it is worth checking (red plastic case with multiple piston adapters?). There is a roll pin in the threaded shaft of the tool that keeps the piston adapter fixed (and rotating). If the roll pin falls out as it did on mine, the piston adapter (and piston) does not rotate and you are pushing against an "immovable object". I found this out the hard way (isn't it always the case), when after struggling for 30 miniutes I stood up and stepped on the roll pin and thought, "now what is this from"? Anyway it might not be the case with your caliper tool but it is worth checking for future brake jobs.

Good luck,
Andrew

bkreigsr · 04-23-2008, 07:25 AM

even with the special tool , it is still a bear.
I had to rig a 'c' clamp up to hold tension on the tool and the rear of the caliper, then turn the tool with a pair of channel locks, while under pressure.
I suspect yours is not frozen, just needs to be turned while pressure is applied.

last time I had my son help with another set of hands and it was a lot easier.

Bill K ...(97 Jetta GL, 02 Jetta TDI, 03 Jetta wagon) (same rear brakes, just smaller than the S4)

cashman · 04-23-2008, 07:32 AM

The tool pictured above is similar to the one you can borrow from Autozone. It comes with several adapters for different caliper sizes and will force the piston back as it rotates. Just saves you having to buy one.
Mark

175K911 · 04-23-2008, 07:32 AM

I've had a number of Audis and the job of retracting the rear piston is virtually impossible without the correct tool. And the ones at my local AutoZone are pretty beat up so I got my own years ago. There are two types- one works and the other is marginal. If you get the one that's basically a cube with a bunch of pins in it, you'll struggle forever. But if you get the true retractor that is threaded and screws the piston back in, it's amazing how well it works even on calipers that appear to be frozen. FWIW- mine came from Harbor Freight.

Are you on AudiWorld? Best Audi related site for technical and mod assistance. (spoken as a 6,700 post regular over there with a 911 in my sig pic). BTW- B5 S4 Avants are great cars!!