vw754

Audi q5.
Replacement discs and pads and new caliper to near side rear... Now.... The caliper was seized, cut a long story short.... The piston came out, along with the fluid..... Car sat with the leaking caliper for 2 days over the weekend and today i fitted the caliper, and pressed the pedal.... Then realised to check the resovoir.i open the cap... . It was empty.🙄.... I ran it dry......

I DO HAVE VCDS IF IT HELPS

So i filled it up with brake fluid, and got an assistant to pump the pedal, eventually fluid came out the new caliper, i thought id do all, but only managed do drivers side front as other ones were so tight to undo i left them.... Just incase they broke.
Soon as i did driver's side fluid came out straight away..... Which lead me to believe there is no issue with air at front??????? 🤔

Now problem i have is the pedal goes down quite far.... But brakes seem to work ok..... Only tested on the drive so not driven it on the road yet.
Is it normal for the pedal to go far down to the ground after replacing rear caliper, discs andpads?

MurrayA4

When you have that large a fluid loss, reservoir completely empty, you really need to bleed all 4 corners.If your bleeders seem stuck use a good closed end wrench and give it a good wack with your hand.Make sure the damned thing is metric ! That will usually work, if not you need to apply some intense heat from a torch etc.

rdA4WtQ5

Use PB Blaster and let it sit to free the stuck bleeders. Also, just to be sure where you say: "got an assistant to pump the pedal, eventually fluid came out the new caliper" you are have the bleeder closed each time your assistant is letting the brake pedal back up?
Just pumping the pedal until fluid comes out without closing the bleeder each pump will cause your exact symptoms as well.

kbrkr

Be Careful. On my Porsche, I had to use an OBD tool to OPEN the ABS Manifold in order to bleed the ABS module as well as the brakes once you let the Master cylinder run dry.

MP4.2+6.0

Not easy to do or know you have it right. Need persistence and thorough bleeding. Get a quart or more of correct fluid for starters.

A piece of thread is already incorrect on assumptions...be careful... Audi brakes are dual diagonal, and have been like forever. Thus left front ties to right rear, and right front to left rear. It is not front front and rear to rear like a lot of older (dangerous) set ups.

Yes, assume air is likely to be in ABS unit at this point. That can take a lot of extra bleeding. The pro way to do this might be a pressure unit on reservoir side, and bleeding at the wheels. If not available, bleed using the two-man, open, pump- close release method, using a clear line where you can really see any air bubbles still coming through. Also be careful in pushing pedal to the floor. Slowly, methodically. If you tear a seal in the master cylinder with extreme extension (BTDT on a much older Audi), that can get damaged and then needs replacing too. For any bleeders that get rounded off in trying to loosen, replace them. Just using an open end wench or "kinda sorta" fits is a recipe for screwing them up. Either quality brake/flare METRIC wrenches, or at least a box end metric wrench is the way to approach it. Forget it with any crescent wrenches, pliers or even correct metric open end.