Was driving back the other night a put my foot on the brake and the pedal went straight to the floor! It did eventually pull up but its now consistent every time I press the pedal it goes to the floor but gives out the same half assed braking effort and eventually stops. Which rules out a fluid leak.

New pads and discs a couple of weeks back and drove perfect for the last few weeks.

The Handbrake works perfectly on both rear wheels so the shoes are still in place and haven't come off.

I'm going down the path of a hydraulic fault E.g master cylinder shagged. If I pump the pedal it builds pressure but the pedal isnt stiff as soon as its running all the pressure goes and the pedal hits the floor.

However if I stamp on the pedal I can still temporarily lock the fronts?

I haven't got time to go investigating the fault indepth so was wondering if anyone else has had anything like this?

Thanks

Julian

Edited 17 October, 201510 yr by xumado

I know you probably know your way around a car more than I do but are you sure that the fluid doesn't just need a change and a bleed?

My pedal after changing suspension then discs and pads for some reason made the pedal go to the floor first time and I had to pump to get any pressure and brake after it was left a month before I drove it. It was like this every time I went for a spin after leaving it for a little bit

Since bleed and fluid change I have had many test drives and it's nice and stiff all the time now so I would probably give it a go first

I know you probably know your way around a car more than I do but are you sure that the fluid doesn't just need a change and a bleed?

My pedal after changing suspension then discs and pads for some reason made the pedal go to the floor first time and I had to pump to get any pressure and brake after it was left a month before I drove it. It was like this every time I went for a spin after leaving it for a little bit

Since bleed and fluid change I have had many test drives and it's nice and stiff all the time now so I would probably give it a go first

Thanks for the idea but I highly doubt it, I was halfway home and and brakes were working fine as usual up until the point when I was slowing from 55/60 to get round a 15/20mph corner... Seat needs a clean as the handbrake came into action to slow down. I'm sure something has just stopped working as it should be but I dont have the time to go crawling under it this weekend :(

Sounds like the master cylinder. Easy enough to replace but you will have to bleed the whole system again. If you haven't already then this would be a good opportunity for an upgrade. Most people on here will recommend a 22mm m/c from a Passat (or probably other vehicles) but I personally feel that is too big and and you have to really push the pedal hard to get the same amount of stopping power. I found the 20mm m/c from a 6n to be a good compromise, you get a slightly firmer pedal fee,l not as much as a 22mm granted but then you dont have to press so hard so a good trade off I think. You will need blanking plugs still though but then ecp can provide these

I know you probably know your way around a car more than I do but are you sure that the fluid doesn't just need a change and a bleed?

My pedal after changing suspension then discs and pads for some reason made the pedal go to the floor first time and I had to pump to get any pressure and brake after it was left a month before I drove it. It was like this every time I went for a spin after leaving it for a little bit

Since bleed and fluid change I have had many test drives and it's nice and stiff all the time now so I would probably give it a go first

Thanks for the idea but I highly doubt it, I was halfway home and and brakes were working fine as usual up until the point when I was slowing from 55/60 to get round a 15/20mph corner... Seat needs a clean as the handbrake came into action to slow down. I'm sure something has just stopped working as it should be but I dont have the time to go crawling under it this weekend :(

Yeah that sounds like something has just gone if you were already driving and used the brakes beforehand, sorry I couldn't be of help [emoji20]

I wouldn't want to pin point something else as I'm not a brake whizz

I know you probably know your way around a car more than I do but are you sure that the fluid doesn't just need a change and a bleed?

My pedal after changing suspension then discs and pads for some reason made the pedal go to the floor first time and I had to pump to get any pressure and brake after it was left a month before I drove it. It was like this every time I went for a spin after leaving it for a little bit

Since bleed and fluid change I have had many test drives and it's nice and stiff all the time now so I would probably give it a go first

Thanks for the idea but I highly doubt it, I was halfway home and and brakes were working fine as usual up until the point when I was slowing from 55/60 to get round a 15/20mph corner... Seat needs a clean as the handbrake came into action to slow down. I'm sure something has just stopped working as it should be but I dont have the time to go crawling under it this weekend :(

Yeah that sounds like something has just gone if you were already driving and used the brakes beforehand, sorry I couldn't be of help [emoji20]

I wouldn't want to pin point something else as I'm not a brake whizz

No worries. cheers anyway fella :)

Sounds like the master cylinder. Easy enough to replace but you will have to bleed the whole system again. If you haven't already then this would be a good opportunity for an upgrade. Most people on here will recommend a 22mm m/c from a Passat (or probably other vehicles) but I personally feel that is too big and and you have to really push the pedal hard to get the same amount of stopping power. I found the 20mm m/c from a 6n to be a good compromise, you get a slightly firmer pedal fee,l not as much as a 22mm granted but then you dont have to press so hard so a good trade off I think. You will need blanking plugs still though but then ecp can provide these

Bleeding the system again is light work compared to what I've done to it so far!

Ill go for a standard cylinder as the brakes are pretty spot on (when they work).

Ill get it delivered and hopefully fitted monday if I've got the time.

Only worry is if a rear cylinder has copped it :/ didnt know if the GTs had a weak spot with the brakes others have come across

Are you sure it isn't a fluid leak? If you build up pressure can you hold it there or does the pedal still go to the floor?

I'd be tempted to try a bleed first before replacing things.

From my experience the only parts of the system that fail are the old steel lines and the flexi hoses.

But if you can do the work yourself a full brake system overhaul is cheap in a GT.

Are you sure it isn't a fluid leak? If you build up pressure can you hold it there or does the pedal still go to the floor?

I'd be tempted to try a bleed first before replacing things.

From my experience the only parts of the system that fail are the old steel lines and the flexi hoses.

But if you can do the work yourself a full brake system overhaul is cheap in a GT.

Defo no leak, fluid level hasn't moved since I've got it.

But that sounds probably like a better idea to do an overhaul as nearly everything else has been changed

One way of proving (or otherwise!) the master cylinder, is to VERY gently, and preferably with your hand, press down the pedal over a period of 3-4 minutes.

If you can get the pedal to the floor by this method, but there is at least some pressure there when you 'stamp' on the pedal, it is almost certainly due to a M/C fault.

If there is unexplained extra travel in the hand brake, it is likely that the auto adjuster(s) are not working or have disengaged.

Regards

Sounds like the master cylinder. Easy enough to replace but you will have to bleed the whole system again. If you haven't already then this would be a good opportunity for an upgrade. Most people on here will recommend a 22mm m/c from a Passat (or probably other vehicles) but I personally feel that is too big and and you have to really push the pedal hard to get the same amount of stopping power. I found the 20mm m/c from a 6n to be a good compromise, you get a slightly firmer pedal fee,l not as much as a 22mm granted but then you dont have to press so hard so a good trade off I think. You will need blanking plugs still though but then ecp can provide these

Bleeding the system again is light work compared to what I've done to it so far!

Ill go for a standard cylinder as the brakes are pretty spot on (when they work).

Ill get it delivered and hopefully fitted monday if I've got the time.

Only worry is if a rear cylinder has copped it :/ didnt know if the GTs had a weak spot with the brakes others have come across

I have had the rear compensator go on me before too, cant remember what the symptoms were but I do remember it was fairly apparent immediately. The symptoms you described were exactly the same as when my m/c went though.

Think you'll find the 6n (20.8mm) m/c will actually be cheaper iirc.

Eurocarparts part number: 132440658

That looks like the same one I'm using in my car. I'd recommend it as an upgrade. I'm using all 4 ports instead of blanking one off. Pedal feel is far better than that of the standard setup.

That looks like the same one I'm using in my car. I'd recommend it as an upgrade. I'm using all 4 ports instead of blanking one off. Pedal feel is far better than that of the standard setup.

How have you done that?

That looks like the same one I'm using in my car. I'd recommend it as an upgrade. I'm using all 4 ports instead of blanking one off. Pedal feel is far better than that of the standard setup.

How have you done that?

By being amazing.....

The easiest way to explain it would be to say I removed the T-piece that is on the passenger side of the engine bay and just turned the 2 lines from that into individual feeds from the M/C. But obviously using all new lines.

LHD G40s (and possibly other LHD Polos) were set up like this as standard so if you are good at googling you may find a diagram of how they set it up somewhere. I just did mine from scratch.

I've got same problem on mine

Found out their was a leak from my passenger side rear cylinder so changed both side rear cylinders, shoes were fine, front discs and pads were fine and drained out fluid out and put new in. Got it upto pressure for about 10 minutes and went back to how yours is, I have got a broken cap on brake reservoir so don't know if that'll be that on mine but I don't have any leaks either on mine

If you pump the pedal can you get the pressure back or is there nothing there at all?

I'd get a decent cap on there sharpish, brake fluid is hygroscopic.

I ended up doing a complete fluid drain as what was in the sytem was pretty shot. but replaced the master cylinder which cured my problem. However I've since in the last couple of days replaced the entire system,Servo, front calipers, discs and pads were done 120 miles before the fault, rear cylinders, drums and shoes, compensator, all fixed lines with new copper pipe and flexis upgraded to braided lines.

Only for the fact of I had the parts available and I've more or less replaced everything else on the car so might as well do the brakes fully

If you pump the pedal can you get the pressure back or is there nothing there at all?

I'd get a decent cap on there sharpish, brake fluid is hygroscopic.

Yeah mate I have to pump a few times to get pressure up and then something if I push hard it stops straight away, it's worse when I'm in town traffic stopping and starting with my brake lights going on and off! People will be thinking I'm trying to get their attention haha

Where can I get a cheap cap from? Looked in eBay and there £20 with sensor on top from China and I don't have VW breakers anywhere in Blackpool

That says to me there is air in the system somewhere then.

I'd get a new cap and try a bleed. Best to see if someone breaking a Polo has one.

You have two circuits, so if a corner leaks you still have some braking. Sounds more like the m/c to me though.

Any chance of a photograph of the upgraded 4 way system you have put on your car? I think it would be such an improvement on what are very basic brakes on the coupe.