Drilling brake discs- advice pls

Robertb · May 2, 2005

Hi all,

The brakes on my 993 Targa judder very gently under light brake pressure, and a quick inspection shows that the disc holes are blocked to varying degree.

Is is practical to drill the holes myself? If so, what is the procedure, what size bit should I use and any special hints?

Thanks

Guest · May 2, 2005

Drilling them shouldn't really be necessary.
The brake dust, whilst sometimes packed quite hard, should be able to be pushed through.

Some people have done it with a jet wash, although I wonder whether this cleans the second inner disc (since the vented discs are made up of two discs). You also need to dry them off afterwards.

I tend to use a drill bit and just poke it through - although it takes some time (there are 144 holes per disc on a 996). You can do it with the wheels on if you have the turbo wheel since the spokes are wide enough apart.

Last time I did it, I wrote down I used a 3.5mm bit, although I thought I used a 4mm the previous time.
A piece of dowel should work as well (and is possibly better).

I had a few holes I could not push through, which I guess is down to some minor corrosion stopping the bit being pushed through.

Melv · May 2, 2005

Drill them out -nice easy job. But you'll need to blow the resultant debris out, I use an electric pump with the mattress inflator bit on -wear a face mask.

For goodness sake, don't jet wash them -I doubt it'll shift impacted brake dust anyway.

Sundeep · May 2, 2005

aye...

wire brush.. drill bit.. what ever works....!

although they do seem to clog up a fair bit ! esp after track days !

but important to clean them, as the disc drilled hole cooling won't work otherwise..

Elliot Davies · May 3, 2005

A 60mm long plastic headed nail for UPVC facias etc. also fits mine a treat.
a gentle tap in blocked holes, the dust removes easily as the nail has grippers on the length of it and obviously gets both sides of the disk too

danofesher · May 3, 2005

I used a 4mm drill bit and managed to do it with the wheels on (I needed to move the car about 4 times).

It may be better to buy a longer bit (or piece of plastic/metal) so you don't need to get your hand in the wheel.

Don't use any power - it's unnecessary and at the back of the disc there'll no doubt be a thin backplate which you'd rather not damage (and possibly other bits that shouldn't get damaged).