Haven't been here for a while Feels good to be back.

Now on topic - I have a 2007 Fabia I vRS with 312mm brake upgrade and Eibach -30mm lowering kit. I feel the brakes aren't running their full capacity and the braking is rubbish. I also think this might be due to wrong brake bias.

I was running the original set 16" wheels (with Bridgestone er300 on them) until recently, but changed to some TT 17s. At first I taught this was due to the cheapo tires the new wheels were running. Changed those to Vrederstein Sessantas 215/40/17 and started feeling strange. When braking hard I feel the rear wheels are locking and applying too much braking power on an empty car. I even tried braking hard when turning and it felt almost like I had the hand brake on.

I have original xenons which come with an auto-leveling system. I was advised that it was also connected to the brakes, so that when you load up the car you get more braking power at the back. Since I have a -30mm lowering kit the auto-leveling might think I am constantly rolling with three fat chicks at the back seat. I have looked at the auto-leveling and besides all the wires, there is a hose sticking out of it, so this might be have to really be a possibility.

How do I change the brake bias? Is there a way to regulate it via VAG COM or by a hardware mod? My car feels really insecure when braking, so any tips and help will be greatly appreciated! Thank you!

The sender for the self-leveling headlights only has an electrical connection. What I think you are seeing is the linkage.

As your car has ABS, it doesn't have a mechanical load sensitive brake pressure regulator.

Are they blead properly?

Have you got the 256 mm rears too?

Yeah, I had cause to put the anchors on on an A road the other day, and the car got a bit of a squirm on. I'm running 312s up front with Tar-ox discs and pads, and standard Pagid 232mm rears, so the balance is a bit out of whack (compared to my old Leon with its 288/232, Pagids all round). Looking forward to getting my 256 rears on, and eventually buying a more "matched" set of discs/pads all round to get some balance back :/

I am on the standard 232mm rears.

As I understand you correctly - there is no way I can adjust the brake bias?

At the front I am running Zimmerman discs and OMP Road&Sport pads. At the back I have a set of Brembo pads, which are about 4k miles old and the standard discs.

Edited 26 June, 201214 yr by Karaibrahim

No, the only way to adjust the brake bias that I know of is to put the bigger discs (and I believe more powerful calipers, ATE ones rather than Lucas) on. This will restore the balance to be more like it should be from the factory; generally speaking cars which came with 288mm front brakes had the 232 rears, 312mm fronts from factory came with 256mm rears, as did the 323mm Brembo setup from the Mk1 Leon Cupra R. So by upgrading the front and not the rear, you're moving the brake bias to the front as a result of that. Once you put the bigger rears on, it should make braking a bit more balanced again as you'd be replicating the factory setup.

mk1 LC had 312mm fronts and 232mm rears, feels no more/less balanced than the mk4 Golf we had previously which did have 288/232. my mk4 Ibiza didn't feel particularly bad when it still had the standard 232 rears, that had 312 fronts as standard

But, what I am saying is that I can feel my car braking harder at the back, then at the front. When braking hard I can feel it starts dragging its rear wheels at some point. Having that in mind - what is the point of putting even more powerful brakes at the rear?

I can't say for certain with your problem, but if you think it's dragging the rear wheels then I would say that could be due to powerful front brakes. When you brake, the front anchors on more than the rear, which causes an element of weight transfer to the front, leaving your rear wheels free to lock up. Whereas with more powerful rear brakes, when you hit the pedal, the rear will be doing more braking causing less weight transfer and keeping the car more stable. That's my thinking on it anyway, I still have to get the bigger rears fitted to see if it makes a difference.

andypandypoos, that's a good point, I'd forgotten that the Mk1 petrol Cupra had 312/232, mine was a TDI so 288/232. I guess part of my problem might also be that the rear of my car is lighter than a Leon due to not having the spare wheel in it at the moment, and I have a good setup on the front (TarOx G88 discs and Strada pads) with standard OEM stuff on the rear.

But, what I am saying is that I can feel my car braking harder at the back, then at the front. When braking hard I can feel it starts dragging its rear wheels at some point. Having that in mind - what is the point of putting even more powerful brakes at the rear?

Either your not braking hard enough, the cF of the pads is wrong or the brakes need bleeding.

Under light braking the ABS applies a large percentage of the braking force to the rears. As you brake harder all the extra force goes to the fronts.

I had a similar issue on my standard vrs, car was all over the place under braking and felt terrible and very unstable., was eventually diagnosed as a faulty master cylinder, putting the braking force mostly into only part of the diagonal circuits.

Modern cars have diagonal circuits on brakes - 1,osf/nsr 2,nsf/osr - or whichever way round it is, to give some braking force if one circuit loses pressure. So maybe take your car to an mot test place and ask them to pop it on the rollers and see if its braking evenly.

I had a similar issue on my standard vrs...

Hm, this sounds logical, but the car was in for an MOT 3 months ago and it only showed slight irregularity on the handbrake test. All other brakes tests were fine.