Q5 Brake pedal goes down after rear discs and caliper

[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..... It was empty.
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 and pads?

 

[AllanG]

Short answer is No! You must bleed all four callipers to ensure there is no air in the system, making sure that, when bleeding, you keep the reservoir topped up with brake fluid.

 

[vw754]

I think that the resovoir was dry.... Could that of got air in the system.... What about master cylinder is it possible to bleed that?

 

[AllanG]

Yes, if the reservoir was dry, then you’d definitely have air in the system. By bleeding each calliper in sequence, starting at the one furthest away from the reservoir, will purge the air out of the complete brake hydraulic system, including the master cylinder.

 

[vw754]

Thanks allanG
So there's no actual bleeding on the master cylinder itself then?
Just doing the calipers will also bleed the master cylinder?

I have no bleed kit only 2 man method (manual pump pedal etc)
Ive heard i can use vcds to bleed it.... Is that any good?

 

[AllanG]

As far as I’m aware, there’s no bleed nipple on the master cylinder, but suggest you check yours.

The 2 man method should work, though a proper bleeding kit is easier.

I don’t have any knowledge of vcds, so don’t know if you can use this to bleed the system.

I also suggest contacting your local Audi or indi dealer to ask their advice, as I haven’t actually had to bleed brakes on a modern car with an ABS system, so my advice above may not be correct.

 

[vw754]

Thanks

 

[vw754]

Ive bled them via 2 man method, don't seem to make much difference really... Even though caliper were squirting out the fluid, is there a chance there's still air in there as pedals nearly to the floor and when u push pedal its hissing air

 

[vw754]

Is it best try with pressure bleeding??

P. S i did 2 man method just until fluid came out of caliper, don't know if thats long enough.... Probably 10 minutes or so.

 

[AllanG]

As you’re not having any luck, I would suggest getting your dealer or indi to bleed your system, as I’m sure they would have the appropriate equipment........sorry I can’t help further, but let us know how you get on.

 

[vw754]

Thanks..... My friend down the garage has a pressure bleeding system said i can use.... Thats what indie use too

 

[AllanG]

^^^Hope it goes well...let us know.