HI everyone, sorry it is a long one, hopefully someone will be committed enough to read it.

 

A few months back I got a new WOF (MOT for UK people) for my 2005 Fabia vRS and they picked up that the front brakes and discs will need replacing soon and noticed that the front left pads were worn more than the right. It was also pulling to the left under heavy braking at high speeds, you couldn't tell around town. So I decided to change the front discs and pads and also the rear brake pads because they were getting low as well. Then I had the brake fluid replaced at the local Skoda dealer and they did a quick inspection and seemed happy with everything. When I was changing the pads the callipers seemed fine, just had to lubricate one of the sider pins on front right.  Since then, the car has still been pulling to the left when braking hard at high speed (indicating another issue perhaps master cylinder), but is also started to get a bit of brake drag when the car was warmed up, about 15mins driving. My poor wife had the worst issue of this one day saying she couldn't get it out of first gear because trying to change gear would bring her to a stand still! I took it into the Skoda dealer to get it inspected and after some testing on the braking system found that the Master Cylinder was causing the brakes to stay on a little and their recommendation was to have it replaced. Replacing this would also fix the uneven brake pull. 

 

I decided to get a second opinion form an independent brake specialist and they also thought the master cylinder would be the cause, but also the push rod needs adjusting because just the slightest touch on the brake peddle would make the brakes bite. 

 

So I decided to order a new OEM master cylinder (turned out to be TRW) which came under these codes; 6Q0611019Q, 6Q0611019C, 6Q0611019E and is called a Tandem Master Cylinder. I had the Master Cylinder installed by the independent guys mainly due to cheaper rate and from dealing with them they seemed really knowledgeable and helpful. They said the fitting went well, no issues, the new Master Cylinder was 2mm different in size which in turn meant it wouldn't have the initial bite the old one had. Also that the Master Cylinder had four ports and came with two plugs, which is understandable because I image the part has to fit a few cars from the VW group.

 

I picked it up and on the short drive home the difference the new master cylinder made was amazing the brakes felt really good. Also it's now braking dead straight, no pull either side. 

 

So bring on the first big drive to work the next day, it's not far only 22km. All was going really well until I was about 2-3km from my office when I went from 100km zone down to a 50km zone. Turned off cruise control and the car started to slow down reasonable quickly, not coasting at all. So I went along a bit further in the 50km zone and I could feel the brakes starting to slowly bite, it was a gradual feeling, not instance.  after going through a round about it got to the point wear the car would barely move. Crap! So I rung the brake guys and told them about it, they said bring it round and they will check it out. I let it cool down for 1.5 hours and then drove it over to them, which made the same thing happen, fine when it's cold and then after about 15mins driving the brakes will slowly start to bite down and lockup. At this point I had to get the car to the mechanic to look at and I turned up with the front brakes smoking away and all four brakes were locked. 

 

They did some tests and decided it must be the new master cylinder. This is where I want any thoughts people might have because i'm not 100% convinced. It had the issue before, just not as bad because the old master cylinder was faulty. Could it be an issue with ABS system or something?

 

If you managed to get through this life story, thanks for sticking with it, and any ideas would be helpful.

 

 

 

 

 

Maybe this will help?

 

http://www.brakesint.co.uk/pdf/technical_assistance_301.pdf

 

I'd say problem with new master cylinder and/or servo. Possibly see this post:

 

http://www.briskoda.net/forums/topic/289024-brakes-stickingbinding-can-anyone-offer-advice/

 

If the garage used the old "pump n tighten" way to bleed the brakes after fitting they could have damaged the seals in the master cylinder. Unlikely but possible. In what way was your new MC 2mm bigger? Diameter or length?

Thanks for that,

 

He measured it from the back of base plate that attaches to the firewall/servo, so I think it was the length of shaft that the push rod goes into, which meant he didn't have to adjust the push rod for brake feel. Plus when driving cold the brakes feel great. They said they bleed the brakes the correct way opening the ABS system. Thanks for the two links, gives more food for thought. I'll feed back to the garage on Monday and see what they say. When releasing the bleed nipples at the caliper the pressure is released so they reckon the caliper pistons must be ok. Just something restricting the back flow somewhere up the system.

 

I was wondering if it's worth taking car for a drive and having brakes bind up and then disable the ABS system and see if they release the pressure.

 

Interesting to note, that other people with similar brake issue haven't used genuine Skoda mechanics either. Could be valuable lesson in you get what you pay for. Trying to save some money might cost you more in the long run. 

 

Thanks for your help.

possibly the servo itself sticking, its a bugger to change tho but maybe next time it locks up try slackening off the 2 nuts holding the master cylinder to the servo,if it releases then it is the servo, or pedal sticking down a bit.

Dont think it's the ABS system as when that kicks in you feel the pump vibrations through the pedal. Try it on a quiet metalled (think that's what they call them in NZ?) road and slam on the brakes. You'll know when the ABS is working ;-)

 

I think it is the brakes slightly dragging. Heating up calipers. Causing expansion. Causing brakes to bind. Possible cleavis pin adjustment necessary. 

In a basic sense, which wheels are actually sticking now when it comes to a halt ? Front or rear ? Anyone bothered to check ? Surely this is relevant to work out where the imbalance is coming from ?

 

Some have fitted the Seat or Ford style rear calipers springs to help a little with the rears not staying on so much (perhaps moreso of mooing fix however).

All four brakes are sticking now. Before the master cylinder change it was only the front left and rear right, the alloy wheel was getting quite hot, where the other side wasn't. However it was never this bad with all four wheels completely locking up. 

 

It's great feedback, getting heaps of things to try, thanks guys.

When the brakes are locked pull the vacuum pipe out of the servo. I'd bet the car then rolls.

I was thinking of the diesels vaccuum assistance myself - but resisting posting to mention that as I would have thought it only assisted with braking rather than actually actuating it ( i.e. through the pedal)

 

You are definitely right though its one of the potential areas to go wrong ( isn't it usually though when its leaking and not offering enough assistance).

 

Be warned with the vaccuum pipe disconnected, braking will seem like you are not !

You don't need to drive it with it disconnected.

Just push it. Changed a few that jam up, fine if you release the vacuum but then hold on.

So if disconnecting the vacuum pipe releases the brakes, would that mean a new pump is required? Don’t really know much about this area.

 

Also I found a bit of information on a VW diesel forum. An owner was experiencing the same issue as me, with the brakes dragging, which for them turned out to be the brake booster rod needing adjusting. From what i gather, the piston on their VW wasn't retracting far enough past the pressure relief hole in the Master Cylinder, causing the pressure to build and then self braking more and more.

 

What you guys reckon?

It will be a new servo (brake booster). As far as I know there is no adjustment on the rod.

Update if anyone is interested.

 

The car stayed with the brake specialists over the weekend so they could look at it today. After doing all the checks he said it doesn't add up as to why all four brakes and locking up. Skoda reckons that the ABS system just needs to be reset, but with 40 years experience on all makes and models he said he's never heard that before on an ABS system, plus the issue is hydraulic. So he re-installed the old MC and drove it round and did some more test again and decided that the front left hand side caliper was dragging a little (which it was to start with) and that all it needs is a refurbishment. Found nothing wrong with the old MC. Also nothing wrong withe the servo either. Just wish he had done this level of inspection to start with.

 

This is a completely different result from what the local Skoda dealer said they didn't even mention it could be the caliper even though it was clear to them when I got them to test the car that the front left brake was dragging. So lots of money down the drain at this point to start all over again. Will have a chat to the brake specialists tomorrow about it all, but I think we will order a refurbish kit for the caliper and see how it goes.

When the brakes are locked pull the vacuum pipe out of the servo. I'd bet the car then rolls.

Hope you didn't pay the specialist anything for that diagnosis! Did you try what techie suggested?

There's a small none return valve in the vacuum pipe. This went faulty on mine making the fronts bind. Unplugging the servo hose released the brakes, easy job to change the valve.