I agree with Ivor on this matter .
In fact I will look at the rear discs on my 1.8T to see exactly what is going on there.
When checking over my car, I did notice the rear discs to be rather small, (front wheel drive) yet on further examination, I notice that the pads are even smaller that the Arc of the disc would allow, because the calliper is a pretty skinny one.
There has to be a design reason, and you may probably find a pressure relief valve to stop excessive braking on the back when the car is forward pitching. this of course because it is front wheel drive, and there is a massive out of balance weight distribution ratio from the centre of the car forward.
Vented discs are not the be all and end all you knowÂÂÂ
! The old solid racing drilled ones were good, the dust and water was pressed thru the drillings ? and using harder hot pads and air scoops on the callipers to keep the fluid cooler worked.
With vented disc you have to change the disc more often, they distort badly in real heavy braking when worn thinner, and tend to collapse on the segments, ok, you need a vernier micrometer to measure the distortion, but never-the-less, new pads on worn vented discs is worse that solid, as they grab like mad in an inconsistent manner.
Be carefull that you don't stop the back of the car too early under heavy high speed load.
Like the golf loads, but rear wheel drive with a heavier LSD differential is far superior IMHO (traction control actually works that way). Makes me an old school driver - ok  If you're racing, you may want some heavy fire bricks in the spare wheel orifice, to keep the stern down.
Change the brake fluid, "bleed it all out" every 20k or 30 months, or your seals will eventually start weeping .
Duncan
