Rear Brake Caliper Won't Compress - Using Schwaben Kit

[hanceyman]

Hi Everyone,

I spent the afternoon trying to swap out my rear pads and rotors. Besides the bolts on the caliper carrier being pretty rusted on, the whole job went smoothly until the very end. I had everything together except the calipers. I bought the Schwaben tool from ECS (http://www.ecstuning.com/Search/Brake_Caliper_Piston_Tool_Kit/ES9747/) to compress the calipers properly. I did the passenger side first, and with a little effort the piston compressed, and I was able to reinstall the caliper on top of the new pads and rotor.

I went to the driver's side to compress the caliper piston on that side, but it wouldn't budge. I tried as much force as I could, but I couldn't get the piston to turn at all.

Has anyone ever had a similar experience or know of any possible solutions? I took the cap off the master cylinder before I started and took a little brake fluid out. The only other ideas I could find from looking around online were either removing the bleeder valve on the caliper itself to relieve pressure or turning on the car and pressing the brakes just enough to get the caliper piston to un-compress slightly and then attempting to compress them again after that.

I was thinking that maybe there's some kind of mechanical issue inside the caliper itself, but I haven't had any issues before. All the rear pads seem to be wearing evenly.

I'm just hoping someone has come across this before or has any suggestions. Thanks for taking a look.

[sa_seahawker]

If it were me, I would disconnect the brake line and then try to push the caliper. If it moves, great, connect the line and try to bleed. If it still won't bleed, then you probably have a pinched line somewhere. If it doesn't, then the piston has seized and it's time for a rebuild or replacement.

Also, just as a matter of FYI advice, I would suggest getting the rotors turned as well. Any auto zone or parts store should be able to do it for cheap.

[hanceyman]

Thanks for your help. I might give disconnecting the brake line a shot tomorrow. Do I need to disconnect the brake line or just the bleeder valve? If I do get the piston to compress after disconnecting the brake line/bleeder valve, would the car be drivable at all without bleeding the brakes, or do I need to flush the system immediately after?

Also, I went ahead and got new rotors and pads. I probably could have had the old ones turned, but I wanted to get new rotors anyway.

[hanceyman]

I ended up taking everything back apart and putting all the old parts back on so the car is drivable until I can get new parts in. I'll be getting new brake fluid and a power bleeder so I can flush the whole system. I also think I'm going to buy a new caliper for the one that seems to be seized.

Does anyone know if it's okay to replace a single caliper? Or should they be done in pairs?

[sa_seahawker]

Thanks for your help. I might give disconnecting the brake line a shot tomorrow. Do I need to disconnect the brake line or just the bleeder valve? If I do get the piston to compress after disconnecting the brake line/bleeder valve, would the car be drivable at all without bleeding the brakes, or do I need to flush the system immediately after?

Also, I went ahead and got new rotors and pads. I probably could have had the old ones turned, but I wanted to get new rotors anyway.

By not bleeding the brakes, you risk having air in the line.

Air in the line = NO BRAKES!
You should always bleed after disconnecting the line.


I ended up taking everything back apart and putting all the old parts back on so the car is drivable until I can get new parts in. I'll be getting new brake fluid and a power bleeder so I can flush the whole system. I also think I'm going to buy a new caliper for the one that seems to be seized.

Does anyone know if it's okay to replace a single caliper? Or should they be done in pairs?

Replacing calipers individually isn't as necessary as replacing the wear items. Pads, rotors, wheel bearings, etc should be replaced in pairs. So long as the other caliper isn't sticking then you should be okay. However, the first thing I found out with my car is that if one side is going, the other side usually isn't too far off. So, to keep some warm and fuzzies, I would replace them both. Just keep in mind that depending on how old your car is and how many miles it has, you may start to see major systems wearing out and needing replacement more frequently. Be prepared...good luck!

[naiku]

I had this exact same problem when doing my rear brakes. It sounds like you kept the caliper on the car? If so, remove it, set it on a work bench, and then use the tool. That's the only way I was able to get mine to budge.

[Brillo]

Loosen the bleed screw. If you can't get the piston to compress into the caliper by applying force to it with the tool (which should be very easy to do, especially with the tool) then I would suspect that the piston is either seized or crooked within the cylinder of the caliper. The later can happen more easily if you've really run the pads down to minimum thickness such that the piston is way out of the cylinder. In the later case you will probably have to get a new caliper because the cylinder walls will be scored. If it is scored some brake shops can re-hone the cylinder to recondition it. I don't know if you can do this with an Audi. Otherwise the safe bet is a new caliper. You do not need new calipers on both sides but someone above did mention (correctly) that the pads and discs should be replaced in pairs.

[hanceyman]

Thanks for all the suggestions. I didn't want to disconnect the caliper this weekend because I didn't have the proper tools on hand to bleed the brakes.

Once I get more fluid and a power bleeder, I'll try opening up the bleeder valve on the caliper with the stuck piston and attempt to compress it again. If that doesn't work I'll remove it and try compressing it off the car. If that still doesn't work I'll swap the caliper. It's good to know that they can be replaced individually, especially since the cheapest I found them new was from GAP for around $250. After whatever happens with that I'll flush the whole system and bleed the brakes.

My pads and rotors are worn, but nowhere close to having the rotors contact the pad backing. The real reason I was trying to replace everything was that I was getting some kind of screeching sound from the rears, almost sounding like the pads were close to worn out. Checking through the service records from the previous owner, it looks like they took the car into Audi for a similar issue, and the dealer notes say they sanded the glaze off the pads or something like that. Interestingly enough, it seems like the noise went away after I took everything apart and put it back together. I gave everything I good cleaning before I put it back on which may have helped. I'll keep an eye on it, but I have a feeling the noise will come back.

[hanceyman]

I ended up ordering another caliper just in case. I took everything apart again and pulled the old caliper off the car. Even with the brake line disconnected and the bleeder valve open I still couldn't compress the piston. I swapped the caliper, put the new pads and rotors on, and did a brake fluid flush. Everything seems to be working fine now, and that squealing noise I was hearing when I applied the brakes is gone.

[crew]

Did you have the parking brake engaged? That will keep you from compressing the piston.

[hanceyman]

Did you have the parking brake engaged? That will keep you from compressing the piston.

Parking brake was disengaged. Even with the caliper completely disconnected from the car I still couldn't get the piston to compress.