Brake advice

[PenguinGTI]

I've posted this in the mk6 section and the Trackdays section. I don't know where is more appropriate so Mods please correct me if I've made a mistake.

Right, I've noticed when the brakes are warm and I brake hard there is a thum-thum-thum comes from the brakes and the steering wheel seems to vibrate/wobble. It occurs pretty much only when I am really pushing it.

Could someone advise me what they think might be wrong. Is it a case of a warped disc or could it be pads?

My tyres are also getting low so could it be a wheel balance issue? The symptoms don't appear during normal driving and braking.

I don't have much experience in this area so all advice is appreciated.

[am1w]

If the surface is damp(especially) and you're breaking very hard, then it sounds like the ABS is being activated due to lack of grip. But check your pads and discs anyway.

[Exonian]

Definately sounds ABS related. Don't forget the various traction control measures also work off the ABS, such as ESP, XDS yadda yadda.
The worn tyres will reduce grip and make the brakes work harder.

How many miles on car/brakes/tyres?

[am1w]

He mentioned 24k about 6 months ago. Must be 30k by now. This is an uneducated guess of course.

[SteveP]

If it happens when the brakes get hot then then it's likely to be disc related. If it's ABS you would feel it through the pedal and not the steering wheel.

[KennyGTI]

I had this happen on my Polo GTI, I fitted Golf GTI brakes on it (OEM), I was racing on a track and must of being doing 140-145 and had to brake relatively hard and got heavy shuddering through the brakes and right through to my steering wheels! At first I thought I had warpped the discs due to the heat but all was fine after letting them cool down. I put it down the fact the brakes were struggling to disperse the heat/gases quick enough hence the design on drilled discs came about? Try going slower in future! 

[PenguinGTI]

I had this happen on my Polo GTI, I fitted Golf GTI brakes on it (OEM), I was racing on a track and must of being doing 140-145 and had to brake relatively hard and got heavy shuddering through the brakes and right through to my steering wheels! At first I thought I had warpped the discs due to the heat but all was fine after letting them cool down. I put it down the fact the brakes were struggling to disperse the heat/gases quick enough hence the design on drilled discs came about? Try going slower in future! 

Ha Ha, Thanks Kenny. The last time it happened was on the Ring so yeah it is when driving pretty hard.

Can I ask for some clarification then. If the discs are warped should I get the sensation every time I brake (regardless of brake temperature) or would it only be when the brakes are hot?

I had it before and got the discs replaced and this stopped it but it was much worse last time. It really unsettled me quite a bit going round the Ring. I don't know if it could be a warped disc again but sometimes I can drive the car and it is fine, it's only when the brakes get warm it does it.

As for solution are drilled/ grooved discs less likely to suffer these symptoms and become warped. I've seen the options on AwesomeGTI but I don't know enough about uprating braking components. Ideally I am generally happy with the OEM discs so I wouldn't want to change unless there is strong conviction.

If it happens when the brakes get hot then then it's likely to be disc related. If it's ABS you would feel it through the pedal and not the steering wheel.

Thanks Steve, so I can definitely narrow it down to the discs then?

He mentioned 24k about 6 months ago. Must be 30k by now. This is an uneducated guess of course.

Good memory Asker, the car is now at 36k miles. The 24k miles was at the time this happened previously (but worse) so it is quite apt you remember that time.

[am1w]

Penguin:
A,
Good people are always worth remembering.
Asker