Broken Brake Disk Retaining Screw Removal (LH Drill Bit)

[Sg113]

Hi all,

Edit: I can't currently get the disk off without removing the rest of the screw

I'm replacing a disk and pads on my R50 '04 Mini Cooper.

I've snapped the brake disk retaining screw:



I bought a new retaining screw and went to drill the remainder of the screw out with a left-handed drill bit and the drill bit didn't drill into the screw, didn't even really make a dent.

These are the drill bits I was using:



Where did I go wrong?

Cheers,
Seb

Edited by Sg113 on Sunday 18th December 10:01

[Fas1975]

That’s just a left handed drill bit. You should have used a bolt extractor set

https://www.screwfix.com/p/bolt-extractor-set-5-pi...

[Pando99]

I'll ask the stupid question first....did you have the drill in reverse?

[DocJock]

You did remember to set your rill for anti-clockwise action? (don't ask me why I'm asking)

[Pando99]

Give it a good hit with a centre pop then drill

[Sg113]

Pando99 said:

I'll ask the stupid question first....did you have the drill in reverse?

yup, definitely had the drill in reverse and drilling in the right direction,

[Sg113]

Fas1975 said:

That’s just a left handed drill bit. You should have used a bolt extractor set

https://www.screwfix.com/p/bolt-extractor-set-5-pi...

I'll get these, but what drill bits do I need to use to drill the pilot hole. Will a cobolt tipped drill bit drill into this snapped screw?

[Ritchie335is]

I wouldn’t bother, they are only there to stop the disc wobbling about when the wheel is off.
If the sheared bit is proud at all just make sure when you fit the new disc the hole lines up.

[OverSteery]

Fas1975 said:

That’s just a left handed drill bit. You should have used a bolt extractor set

https://www.screwfix.com/p/bolt-extractor-set-5-pi...

The devil's tool.
Very easy to snap them off and then you are in real problems, because you have a centre of hardened material to (fail) to drill out.

I would never use one again.

[Sg113]

Ritchie335is said:

I wouldn’t bother, they are only there to stop the disc wobbling about when the wheel is off.
If the sheared bit is proud at all just make sure when you fit the new disc the hole lines up.

Thanks but I need to replace the brake disk and I cant while that retaining screw is in there

[hyperblue]

If the screw's snapped and you can get the disc off ok, do you need to remove the remnants of the old one?

The screw doesn't serve much purpose.

[p4cks]

hyperblue said:

If the screw's snapped and you can get the disc off ok, do you need to remove the remnants of the old one?

The screw doesn't serve much purpose.

This.

[Sg113]

hyperblue said:

If the screw's snapped and you can get the disc off ok, do you need to remove the remnants of the old one?

The screw doesn't serve much purpose.

I should have put that at the top, I cant get the disk off (half the screw is still in there) holding it together

[kambites]

Ritchie335is said:

I wouldn’t bother, they are only there to stop the disc wobbling about when the wheel is off.
If the sheared bit is proud at all just make sure when you fit the new disc the hole lines up.

I've not had any of those grub screws on my car since they rounded off while I was rebuilding the suspension. You just need to make sure that if the screw is standing proud, the disc is lined up correctly (or file the screw down to flush with the hub).

ETA: Ah I see you can't get the disc off, that's rather different. When mine rounded off I just drilled the head off the screw using conventional HSS bits. Then wallop the back of the disc with a rubber mallet (or put a piece of wood against it and hit that with a hammer).

[Paul_M3]

Sg113 said:

Thanks but I need to replace the brake disk and I cant while that retaining screw is in there

It looks like the head is gone though. Are you sure the disc isn’t just stuck against the hub? I’d be hitting the disc with a mallet right now judging by your photo.

[Sg113]

Thanks for the advice lads,

A few people are saying try harder to get the disk off as the head of the screw is off.

I'll give that a go now, might be that I just wasn't trying hard enough to get that disk off.

Cheers all

[evil.edna]

Ritchie335is said:

I wouldn’t bother, they are only there to stop the disc wobbling about when the wheel is off.

This. They also stop the disc from falling off the hub onto someone's head during production. The cars are often conveyed over the factory floor during the production journey with the discs fitted but with no carriers or calipers. The little screw is all that keeps them on the hub during their "flight".

[andy43]

It should come off if you’ve drilled the head off the screw. Rust will be the only thing holding it on. Once the disc is off it may be easier to get the remains of the screw out but if you can’t it’s honestly not a problem as long as the new disc seats ok on the hub. I suspect those screws are only there to hold the brakes together before the wheel goes on when the car is built.

[hyperblue]

Sg113 said:

hyperblue said:

If the screw's snapped and you can get the disc off ok, do you need to remove the remnants of the old one?

The screw doesn't serve much purpose.

I should have put that at the top, I cant get the disk off (half the screw is still in there) holding it together

Ah ok - you sure the disc isn't just seized to the hub? Hard to tell from photos, but looks like screw head is gone and the disc would be clear to come off. Try encouraging the disc off the hub will a mallet.

You have my sympathy, always found these screws were seized and easy to round off when I had Mini's.

I see i was beaten to it many times

[p4cks]

Use a mallet on the back of the disc to persuade it off too