Spongy brakes after new calipers

[VagCabby]

Hello, my wifes car failed its MOT on both rear calipers sticking on which has caused the discs to over heat.

today ive changed discs, pads and fitted two new calipers to the rear. Clamped both rear brake lines but one clamp popped off when fitting the new caliper so guessing abit of air got in the system. Anyway the brakes work fine but are spongy as in the pedal travels further before it bites. Ive tried bleeding 3 times now!

Is there a special routine to doing audi bleeding? Ive bled brakes on cars for years and never had this issue. Are A3s genuinely a pain in the **** to bleed? I undersrand VCDS can be used to purge the abs pump but can't see that air would have got in there. Fluid never dropped enoth to let air into the system

any help would be great.

 

[fangio]

Don't forget though, the brakes will be quite spongy until the new pads have bedded in, maybe 500 miles or more on the rears!

 

[c_w]

But with brand new pads and discs fitted together there should be a good perfect flat surface so pedal feel should be reasonably normal.

 

[SteveMcB]

Not trying to sound cheeky but I've heard of calipers being fitted upside down, making them impossible to bleed

 

[VagCabby]

It feels like theres air in the system. 8Ps dont have any bleed nipple on the master cylinder do they?

Haha deffo not fitted upside down, not possible with the handbrake mechanism but thanks for the thought

 

[ninjakid]

Maybe you need to put fresh brake fluid. Current fluid could of over heated and ****** itself.

 

[VagCabby]

Think most of the old stuff has come out already due to me trying to remove the spongyness! Used a litre of fluid so far. Gunna give it another go tomorrow and do the clutch at the same time as every forum I read says you should bleed the clutch aswell when doing brakes. Going to try a ABS purge aswell and see what that does

 

[Boon]

Don't forget though, the brakes will be quite spongy until the new pads have bedded in, maybe 500 miles or more on the rears!

Never heard that before tbh!

You've obviously got air in system, how are you trying to bleed them, pressure fed/suction or the age old two man system... They don't like being done by the two man method.

There is a procedure for doing the whole lot, iirc it's front nearside, rear offside, front offside, rear nearside

I'm also confident VCDS plays a part in successful bleeding, but should be possible with a good suction/pressure system

 

[c_w]

It is true badly bedded pads can cause longer travel until the pad face meets the disc properly, more on old discs with worn grooves and new pads.


How have you been bleeding? with a pressure bleeder?

I personally would leave the clutch, this may introduce further problems for you! (I struggled to bleed mine at first when I changed the clutch, so if the clutch is fine, I'd leave it). Yes it shares a supply, but it is separate in terms of the main brake system as the clutch just takes a pipe high up off the reservoir (actually seem to have to overfill it to get fluid down the clutch system).

 

[heap1000]

I had my rear calipers done and new pads (not discs though) and mine felt awful! You had to push the peddle nearly all the way down to the floor! After a couple of days I took it back for them to check. They took it out for a test drive and tested it on some breaking machine and they said it was fine. Picked it up and it felt a lot better but they insisted that they did not do anything extra to them. Maybe they do just take a while to break them in.

 

[Sidhu88]

Never heard that before tbh!

You've obviously got air in system, how are you trying to bleed them, pressure fed/suction or the age old two man system... They don't like being done by the two man method.

There is a procedure for doing the whole lot, iirc it's front nearside, rear offside, front offside, rear nearside

I'm also confident VCDS plays a part in successful bleeding, but should be possible with a good suction/pressure system

What he said! VCDS has to be used. You activate the ABS pump i believe which builds up pressure within the system (or something like that from what i read). Further to this, make sure u use Low viscosity dot 4 fluid, or any dot 4 which is suitable for systems with ESP.

Edit:

Here you go....

Brake fluid and clutch bleeding and flush - mk5+ VW | VW TDI forum, Audi, Porsche, and Chevy Cruze diesel forum

 

[fangio]

Never heard that before tbh!

You've obviously got air in system, how are you trying to bleed them, pressure fed/suction or the age old two man system... They don't like being done by the two man method.

There is a procedure for doing the whole lot, iirc it's front nearside, rear offside, front offside, rear nearside

I'm also confident VCDS plays a part in successful bleeding, but should be possible with a good suction/pressure system

The pads/shims/discs etc. come factory fresh and need time/miles/heat to 'mate' with each other; until then, they tend to push the pistons back ever so slightly, giving the pedal further to travel. A new car's brakes aren't as firm as one that's done 5000 miles.
You can imagine how little movement the pistons have for a lot of movement of the pedal when you see the tiny amount of fluid that escapes with a full pedal press.

So you don't get a solid pedal until they are fully bedded in.....

And VCDS isn't needed.

 

[VagCabby]

Cheers for the help guys. Before i was using the old 2 person method. Bought a pressure bleeder and thats done the job, loads of air came out using it and now the brakes are back to normal! In for its re test on the MOT on monday so should pass with flying colours

 

[c_w]

Yep, I would always use a pressure bleeder, never 2-man pump/release/bleed method.

 

[Chilly]

Can you guys recommend a pressure bleeder?

Thanks

 

[c_w]

I've used a Gunson's one for years, seems fine.

 

[MrLapou]

This sort of vacuum pump is the biz.
Search around for either metal or plastic versions.

Bike-It Brake Bleeder / Vacuum Pump - Demon Tweeks

 

[makster1978]

hello everyone heres my first post,i have just bought my first a3 1,8t 99 I have replaced all disks and pads but along the way lost some brake fluid replacing a rear caliper and ended up 2 man bleeding on all calipers with engine off and got a rock solid pedal but as soon I started it pedal droped straight to the deck,i was told then to bleed the nipples on the master 3 or 4 times which did and recovered maybe 40% of pedal back,i am stuck what to do next,i have read about abs activation but that's way over my head I want to do this myself as trying to save on garage fees and it needs running in for mot,if I use a easy bleed will this get the full pedal back and also can I bleed the full system from just the master or will I need run round the calipers again? cheers guys

 

[c_w]

If you replaced just a rear caliper, then the only way air would have got in would be on that brake line. I just wouoldn't bother with 2-man bleeding, it doesn't seem to work on modern cars like it used to. A pressure or vacuum bleeder is definitely worthwhile. You only need to bleed at the caliper, not the master cylinder (I assume by bleeding here you were undoing the brake line unions??).

Pedal always feels softer with the engine on due to servo vacuum boost.

 

[Daggerit]

When I swapped over my A3 callipers for S3 jobs I was told that there was a specific method of bleeding to make sure that you got all the air out of the system. It involved rear and front callipers even though I'd only replaced the front. Made a big difference to the pedal feel before and after.

Only problem is I can't remember the sequence. It was diagonally opposite wheels if I remember rightly but can't remember where to start, it's been almost half a decade since I did mine. Lol.

 

[makster1978]

intresting.so when is it time to activate the abs pump assuming theres air inside it,before or after the bleed up?,i had a macanic come out again to bleed the system and he never used a vacumn to do this he just said let gravity take its course lol,he got them no harder than I did but did fix my handbrake.

 

[Rjw76]

Hello, my wifes car failed its MOT on both rear calipers sticking on which has caused the discs to over heat.

today ive changed discs, pads and fitted two new calipers to the rear. Clamped both rear brake lines but one clamp popped off when fitting the new caliper so guessing abit of air got in the system. Anyway the brakes work fine but are spongy as in the pedal travels further before it bites. Ive tried bleeding 3 times now!

Is there a special routine to doing audi bleeding? Ive bled brakes on cars for years and never had this issue. Are A3s genuinely a pain in the **** to bleed? I undersrand VCDS can be used to purge the abs pump but can't see that air would have got in there. Fluid never dropped enoth to let air into the system

any help would be great.

Unfortunately I can't offer help here as I was about to type exactly the same question (although only one caliper changed (rear off side) due to it ceasing on my wife's car). Like you, I clamped the brake line and made sure that the fluid level didn't drop too low in the master cylinder. I saw a few bubbles come out when I bled the brakes, but after several attempts at bleeding that section of the system, the pedal still feels very spongy and has excessive movement. My wife ended up taking the car to a garage who looked at it (of course they first complained that they shouldn't even look at the car as it had been worked on at home!). They said the brakes were fine (although I don't think that tested the brakes on a rolling road) and the sponginess might be due to the Master Cylinder being on the way out - personally I think this is unlikely as the brakes were firm before changing the caliper.