Drilled brake disks

[sawood12]

What are peoples feelings on drilled brake disks? I know this is a controversial subject but I will need new brake disks later on this year and fancy giving drilled disks a go. Is cracking still a problem?

I've had grooved disks on previous cars and did notice an appreciable improvement in braking performance even with standard pads but at the expense of pad wear, so I would expect that you should get improved braking performance from drilled disks?

Cheers.

 

[danmason]

I guess if you have the right wheels for it then the visual effect is nice, not sure I would bother though as IMHO the OEM discs do the job just fine - although I do use Mintex pads now, which on my car had an extremely noticeable effect on braking performance (and last a loooong time).

 

[John Sims]

I'm very pleased with my drilled disks and, so far, have no evidence of cracking. I managed to heat them up sufficiently to burn the nice Halfords silver caliper paint off the bells, so they have been used.

I have a tendancy to comfort brake on the road, i.e. I brake relatively early and gently. Without drilled disks this can polish the surface of the pads and reduce bite. With drilled disks the pad surfaces tend to get scraped and so the polishing problem is much reduced.

As you noted previously, there are many arguments for and against drilled disks but, to my mind, the reasons for outweigh those against. I list below some of these points and have little doubt that more will be added:-

For.

Cleans surface of pads
Removes water between pad and disk in the wet
Removes gas produced when heating pads which can cause a layer between pads and disk
Reduces unsprung weight
Look dead cool

Against

Might crack
Reduce disk volume and heat sink potential
Reduce disk/pad contact area

 

[Hilux]

To reduce the stress crack incidence there is a company that `dimples` the discs ie: part drills them both sides offset, same effect but the metal grain isnt sheared through the disc with a complete hole

 

[944Turbo]

I cracked my non drilled discs on a hot trackday at silverstone, there are lots of little cracks in the surface in the centre of the discs. If they had been drilled they may not of cracked or they may have cracked more seriously. I think cracked disks is a problem on GT3's with holes driven hard on track, though JZ machtech said a change of pad material helps to prevent it.
Tony

 

[Diver944]

Yes a very controversial topic and luckily we all differ in our view []

I personally prefer solid disks, and have never had a problem with them. I agree that drilled disks do look nicer but you do hear worrying stories about cracking. Some modern sportscars have holed disks but these are generally cast in at manufacter and not drilled like the aftermarket ones for our cars.

The one thing that swings it for me is that if you look around the paddock at race meetings, most race cars (if not all) use solid disks

I 'think' that drilled disks originally came from motorbikes, because they do not have space for a wide vented disk like we do.

 

[eastendr]

Hmmm...

 

[danofesher]

If you're going to do track days stay well clear of drilled discs - two track days and my brakes are shot - with discount a mere £940 for parts alone (discs/caliper bolts)!.

 

[eastendr]

When we used to race two group A RS500 touring cars, we used to use AP drilled. Admittedly treated as a consumable, but wear - not cracking was the main problem.

 

[Melv]

That's because, me danno, you didn't do a cooling down lap and leave the brakes alone....

Sure, my drilled discs crack, but over a period of time.....