brake expert required.

[Effect]

Having a little problem with my brakes.

Some heavy braking one night made them go a bit "squishy"
took them to local garage who bled them and made them more "squishy"
took them to VAG specialist who bled them with VAG COM and got them less squishy.

What the vag specialist found was when the front two brake pipes were clamped the pedal went hard again and clamping the rear brakes made no difference.

They reckon the front calipers are probably knackered.

I want to know before shelling out on unessassary parts is it likely to be the calipers or master cylinder ?
I have recently put new pads and disks on and that hasnt made a difference other than perhaps make it slightly more squishy feeling again, which was initially quite bad and now I have used the car a bit they have bedded back down again.


Hope you can help.
Fingers crossed
James

 

[NHN]

did they take the calipers of to check the pistons action & seals etc, is there any lower fluid levels etc, speculating here, they should have checked them before floating ideas, I cant see both calipers going at same time tbh, they're fairly reliable so could be abs/cylinder, damn gotta get elsa working again now.

 

[Effect]

No they didnt take anything apart.
fluid level is NOT dropping at all + cannot detect any leaks anywhere.
how do I go about eliminating different components of the abs system ?

 

[Mr.G]

I'd suggest you try fitting braided brake pipes/hoses. I puchased a 335mm brake kit for my Subaru Imprea RB5 some years ago and didn't change the brake pipes/hoses. They are fairly inexpensive and are definately worth a try. Mine made a big difference to the bite and feel of the brakes.

Hope that helps some!

G

 

[666markyboy]

took them to VAG specialist who bled them with VAG COM and got them less squishy.

Is there a hidden Menu for doing this ??

 

[Jimmybuckrogers]

Brake system Here's the procedure from ELSA workshop guide. Looks a right pain in the **** but something I'll be tackling myself in the next week or two.



By the way, I think the VAS 5234 can be substituted with a pressure bleeding kit that can be found in Halfords or at http://www.gunson.co.uk/item.aspx?cat=674&item=1818
(someone please correct me if I'm wrong!!)







Pre-bleeding

• [SIZE=-1]‒ [/SIZE]Connect up brake filling and bleeding appliance VAS 5234 or V.A.G 1869 A.
• [SIZE=-1]‒ [/SIZE]Open bleed screws in prescribed sequence and pre-bleed brake calipers.

• 1 - Simultaneously bleed both front left and front right brake caliper
• 2 - Simultaneously bleed both rear left and rear right brake caliper

• [SIZE=-1]‒ [/SIZE]With bleeder bottle hoses attached, leave bleed screws open until the brake fluid which emerges is free from bubbles.

Bleeding
→ Display on VAS 5051:

• [SIZE=-1]‒ [/SIZE]From list -1- select diagnosis function "04 - Basic setting".

Note:
ABS warning lamp flashes in the course of the following operations.

→ Display on VAS 5051:

• 1 - Enter display group

• [SIZE=-1]‒ [/SIZE]Use keypad -2- to enter "001" for "Display group number 001" and confirm by touching Q key.

→ Display on VAS 5051:

• 1 - Basic setting
• 2 - Display group 1
• 3 - Press and hold pedal ...

• [SIZE=-1]‒ [/SIZE]Press pedal firmly and hold in position.
  • [SIZE=-1]‒ [/SIZE]Pedal sags, hydraulic pump starts up briefly, pedal returns

Display on VAS 5051:

• 3 - Release pedal; FR/FL bleed screws OPEN <>

• [SIZE=-1]&#8210; [/SIZE]Release pedal, open front bleed screws.

• [SIZE=-1]&#8210; [/SIZE]Touch s key to switch to display group 002.

&#8594; Display on VAS 5051:

• 1 - Basic setting
• 2 - Display group 2
• 3 - Please wait .. (10 sec.)

• [SIZE=-1]&#8210; [/SIZE]Wait 10 seconds.
  • [SIZE=-1]&#8210; [/SIZE]Hydraulic pump starts up briefly

Display on VAS 5051:

• 3 - Press pedal 10X; bleed screws CLOSED <>

• [SIZE=-1]&#8210; [/SIZE]Press pedal 10 times, close front bleed screws.

• [SIZE=-1]&#8210; [/SIZE]Touch s key to switch to display group 003.

&#8594; Display on VAS 5051:

• 1 - Basic setting
• 2 - Display group 3
• 3 - Press and hold pedal ...

• [SIZE=-1]&#8210; [/SIZE]Repeat bleeding procedure as described above.
• [SIZE=-1]&#8210; [/SIZE]Touch s key in each case to switch to next highest display group until display group 17 is reached.

&#8594; Display on VAS 5051:

• 1 - Basic setting
• 2 - Display group 17
• 3 - Partial bleeding over ...

• [SIZE=-1]&#8210; [/SIZE]Terminate function "04 - Basic setting" by touching &#9666; key.

&#8594; Display on VAS 5051:

• [SIZE=-1]&#8210; [/SIZE]From list -1- select diagnosis function "06 - End of output".

&#8594; Display on VAS 5051:

• [SIZE=-1]&#8210; [/SIZE]Switch off ignition and unplug diagnostic connector when this display appears.
• [SIZE=-1]&#8210; [/SIZE]Brake system must then be bled => Page 47-19.

Special feature of right-hand drive vehicles:
&#8594; If one chamber of brake fluid reservoir is completely empty, brake master cylinder must be bled at bleed screws -arrows- on completion of basic setting.

 

[Khufu]

I had squidgy brakes on my old A3 after all the fluid drained out of the system while it sat on our ramp over night. Used the vagcom to bleed the ABS just in case but I eventually found it was an 8mm bleed nipple on the side of the master cylinder. It could be worth checking?

 

[jcb]

change your fluid for something decent (SRF etc) and get braided pipes before you start replacing calipers.
how old is your fluid?

 

[Effect]

Fluid is brand new DOT 5 that was put in perhaps a month ago.
Master cylinder was bled as well, but brakes remained squishy.

The problem first appeared after a very very heavy session of heavy heavy braking. (so as if something was broken from too much force from the brake pedal)

 

[s3_kev]

sounds like you may have a dodgy brake hose thats slightly colapsing, id try changing brake hoses first even for standard replacments as an alternative, however i recently had a brake pipe failure and lost my brakes completly at the master cylinder and have bleed the brakes out worked the abs and bleed the master cylinder too and my pedal is still a little spongey compared to before,