Time to flush the entire brake system?

[kaanage]

Earlier this year, I have my front brakes updated from the stock TDi 256mm setup to the 288mm GTi setup in the hope that I would not overheat them during trackdays - particularly Sandown where I would get them cherry red as my braking improved.

Unfortunately, I have done 2 trackdays since the upgrade and I seem to keep boiling my brakes - the pedal almost goes to the floor after the first couple of laps of hard use for the day and loads of bleeding is then required to remove large volumes of gas from the system else it becomes very difficult to commit to braking late and heel-and-toeing goes out the window.

Do I need to do a complete flush of my brake fluid and how much am I likely to need?
Or could it be that there is air in the ABS unit that is coming out when it triggers when I over brake? (although I deliberately triggered the ABS multiple times one day on the road to test this without the pedal going soft)

[h100vw]

Earlier this year, I have my front brakes updated from the stock TDi 256mm setup to the 288mm GTi setup in the hope that I would not overheat them during trackdays - particularly Sandown where I would get them cherry red as my braking improved.

Unfortunately, I have done 2 trackdays since the upgrade and I seem to keep boiling my brakes - the pedal almost goes to the floor after the first couple of laps of hard use for the day and loads of bleeding is then required to remove large volumes of gas from the system else it becomes very difficult to commit to braking late and heel-and-toeing goes out the window.

Do I need to do a complete flush of my brake fluid and how much am I likely to need?
Or could it be that there is air in the ABS unit that is coming out when it triggers when I over brake? (although I deliberately triggered the ABS multiple times one day on the road to test this without the pedal going soft)

The system probably holds about half a litre maximum. A litre would ensure a thorough swill out though.

A tip from me try and find a coloured fluid, so you can see when it has come through. I have seen green. blue and clear. At least for the first change, then stick with your preferred performance stuff. I am looking to do mine with Penrite RBF next.

I also have a Motive power bleeder which makes like easy. I also found that doing the output tests on the ABS with VCDS improved the pedal no end.

Gavin

[kaanage]

Thanks Gavin.

I was thinking of getting a vacuum kit like this - https://www.vidaxl.com.au/p/210071/b...th-fill-bottle

With the VCDS ABS test, do you need to trigger this while bleeding the system? I may have to bite the bullet and buy a cable

[h100vw]

Thanks Gavin.

I was thinking of getting a vacuum kit like this - https://www.vidaxl.com.au/p/210071/b...th-fill-bottle

With the VCDS ABS test, do you need to trigger this while bleeding the system? I may have to bite the bullet and buy a cable

I have both and the Pressure kicks the arse out of the vacuum one.

motive power bleeder | eBay

Got mine of ebay.com.au and it had an ECS sticker on it...

Get a cheap cable and buy a license for $99USD?

Just do the output tests sat in the car. In the real word you would have the car with the wheels in the air so you can spin them. It cycles through locking and releasing each wheel while you have the apprentice check the results.

Gavin

[kaanage]

Thanks once again, Gavin

Is this the correct procedure for the ABS test?

From Brake bleeding, brake fluid changes - IMPORTANT - page 1 - Technical Workshop - MK5 Golf GTI

For using VCDS (or the OEM VAS5051 or VAS50502), you need a minimum of 11.5 volts in the battery. Fire up VCDS, click on 'Select Control Module', 03-ABS brakes - then . . . . I can't remember (senior moment) . . . I think it is 'output tests' (or similar). Basically, on the Golf, it takes you through various system functional tests for the four individual circuits. If you have never done this before - you might ***** yourself when the pedal starts grinding away really loudly - don't worry - this is perfectly NORMAL. Oh, and if you are a weakling, you'll prolly get leg ache from holding the pedal so hard. :ashamed: Now when it does its 'grinding' bit on each wheel circuit, you need to let it grind away for at least 30 seconds (this is what gives the leg ache!) for each wheel.

Then go round each wheel and bleed again. Don't be shy about using 2 litres of fluid - more is definatly better in this respect.

Oh - and if you have a manual gearbox, don't forget to bleed your clutch too.

Or is it this? (from How to bleed ABS pump through Vag.com? - TDIClub Forums)

In VAG-COM:
[Select]
[03 - ABS Brakes]
[Basic Settings - 04]
Group 001
[Go!]

Once you hit GO! the screen says to depress pedal and hold
You have to press the pedal HARD. Seriously, pound the pedal like you're about to drive over a cliff. Remember to hold the pedal down!

The pedal will drop, the pump runs briefly, then the pedal comes back up.

Take your foot off the pedal.

I think it wants you to click on OK at this point.

The screen says something like FR/FL bleed screw OPEN.

Open both front bleed screws. Obviously, on each bleed screw you'll have some tubing going from the bleeder into a catch jar.

Click on OK (or DONE or something like that).

Pump runs for 10 seconds, pushing fluid out of the bleeders into your catch jars.

Screen says something like: Depr. pedal 10X; bleed screw CLOSED

Depress pedal firmly 10 times, then close both bleed screws.

Click OK.

You'll get sent back to the depress pedal and hold screen and repeat the cycle. It goes on for like 10 or 15 cycles. I never got a finished message, I just did it until the screen said N/A.

It is easier with two people. One in the car pressing the pedal and working Vag-Com, the other outside opening and closing bleeders and making sure the master cylinder doesn't run dry (very important!).
If you're doing this solo, put the laptop on the driver's side roof so you can access it easier. It's also a great workout as you run in and out and around the car.
After the ABS pump is bled, you can then bleed the rest of the system as normal.