Grooved and Drilled - Increased noise

[nc35]

On the ST forum the same disc were being used for track without problems. Well actually recommended.

I will keep an eye on them any problems they will be replaced with STD solid ones.

So I am assuming that most of the discs out there on BMW and the like are forged not drilled??   

[DaveB@Vagbremtechnic]

I'd agree with nearly everything said so far....

I've just got a load of rotors from a race team and "in the box" were a load of drilled rotors that had small hairline cracks in them radiating between the drill holes. So before I approached the guy I bought them off I spoke to tech support at AP racing who basically said dont worry, off you go and have a nice weekends racing on them!!

I think common sense needs to prevail here, theres three different applications for your car regarding braking, theres:

1. Road Driving
2. Road Emphasised Driving with Trackday capability
3. Good Trackday Capability with compromised comfort on the road.

If you are in category 2 and 3 and have uprated calipers/discs/pads then by definition as far as VW are concerned you are off-piste.....Not a problem in itself, but I was having the conversation with a ED30 owning balloon flying aircraft engineer (myself being involved in aviation as well) and we agreed that however "mild" your braking mods are, you have just given yourself another maintenance inspection other than your regular servicing items such as fluids and tyres etc. Quite common to mod something on an airplane but along with the mod comes a modification to the serviceing requirements/maintenance manual incorporating inspections to that mod if you get my meaning

In essence fit full blown wafer thin ligtweight drilled race brakes if you like, just every 1000 miles or after every hooning sesh get the wheel off and have a bloody good look around them with a good torch. This is how small cracks are detected before they get to big ones.

Im still trying to find the set of brakes that perform well on the track, are quiet on the road and can go 10000 miles without getting looked at.

So IMHO fit drilled discs if that floats your boat, if you're regularly hooning fit grooved, if you like the aesthetic look of drilled and grooved go for it. Just every third tank of fuel show em you care and check your pads and discs over close up and remove any doubt and catch any issues early.

Theres also different qualitys of drilled discs, some of the worst ones are Audi RS performance stuff with drill holes going straight through the ribs between the vanes and then the next hole being drilled to fresh air so some differential cooling taking place defo, some porsche stuff is the same or sometimes cast and then you get the Porsche Carbon Stuff which is drilled perfectly all in the vanes and then you get AP racing carbon rotors that are neither drilled nor grooved!!!

With all the manufacturers doing grooved drilled or both its unlikely one is less safe than the other but as above as Animal said keep an eye on them

[nc35]

Dave thank you again.

You sure do know your stuff. Also the guys in Rochdale are very helpful and well worth knowing.

As an indication of my driving style I get high 30's MPG lot of motorway stuff. When on the back roads I usually have the dog in the boot. Quite rare I go for it. Got a motorbike for that.

No interest in track days or stage tuning the car.

Thanks again for all your imput, I will regularly check the discs, with a torch.

 

[animal]

Dave I couldn't agree more. It's the modification to your maintenance regime that is most vital, and this goes for any tuned vehicle and we're not just talking brakes either. I dont think we'll ever see a perfect compromise between performance and longevity when it comes to a lot of performance parts, unless of course you can stretch to carbon-ceramic rotors, but this is the nature of the game. I buy soft tyres because they grip well. The trade off to this is that they dont last as long. The same applies to my disc rotors as my Ferodo pads chew through them quicker.

I too have seen some very poor 'OE' discs, I know the drilled front discs on the CL/SL55 AMGs were prone to bad cracking. The issue is, once there are small cracks that are visable, it can become a bit of a game of Russion roulette because of the way cast iron fails. The cracks could stay as they are for ages and not get much worse, or they could fail completely without warning once the strength of the disc has been compromised. So just to reiterate - keep an eye on them!

[nc35]

Funny thing is. 

On the way home from Chester to Leeds the check pads warning light has gone off!!!!

Will have to investigate further this weekend.

Will still be fitting the new discs and pads.

For bad crarcks google drilled disc cracking.  Some Brembo rotors with huge cracks.
Can't t remeber which post done sooooo much reading, but if I find it agan I will upload the link a picture.

DaveB if you are still following the post do you have a link you would recommend for replacement procedure?
From memory you don't approve copper grease. I have always used it in the past.