best way to remove brake disc retaining allen bolt

[wjwren]

come to change the disc brake on my 645 and the allen key head has gone. What's the best way to remove? It's a 6mm from memory

Would a tap and die set work?
thanks

Edited by wjwren on Tuesday 12th January 14:33

[trickywoo]

It is flush or is the head clear enough to get a socket on?

Irwin bolt grip will hold on a smooth head if it'll fit.

I suspect otherwise you may be looking at drilling it out. Good luck.

[wjwren]

no the head is flush

[eliot]

drill the head off with a drill the same diameter as the head.

[DVandrews]

I have managed to knock a few round with a small punch in the past on the periphery of the screw, if you make a small indentation in the rim first then tap it round.

Dave

[8Tech]

As you are replacing the disc anyway, hit the disc from behind with a club hammer the opposite side of the centre of the hub and the screw will distort and shear. You are effectively levering the disc against the screw.Once the disc is off, you should be able to easily remove the remains of the screw with pliers.

[helix402]

Don't forget to put a wheel bolt loosely in before hitting the disc off from behind.

[wjwren]

eliot said:

drill the head off with a drill the same diameter as the head.

might be a silly question but will the main part of the bolt nut be stuck in then?

thanks

[t400ble]

wjwren said:

eliot said:

drill the head off with a drill the same diameter as the head.

might be a silly question but will the main part of the bolt nut be stuck in then?

thanks

Yes, but the disc will be off

[wjwren]

replacement bought today

[wjwren]

t400ble said:

Yes, but the disc will be off

so once the disc is off i should be able to use molegrips to fetch it off?

[t400ble]

If enough thread is showing, yes.

You don't 'need' the retaining bolt, does very little other than help when removing pads etc

[eliot]

wjwren said:

replacement bought today

Use a drill sized to the smaller part of the head rather than the larger narrower part. Once you have drilled enough, the narrow head will fall off and you will be able to get the disk off.
Then plenty of wd40 and molegrips should get it out. Otherwise just clean it up a bit and leave as-is.

[tr7v8]

8Tech said:

As you are replacing the disc anyway, hit the disc from behind with a club hammer the opposite side of the centre of the hub and the screw will distort and shear. You are effectively levering the disc against the screw.Once the disc is off, you should be able to easily remove the remains of the screw with pliers.

Please don't you'll brinell the bearings for a start. Also Allen bolts are tough I doubt it will just shear off. If all else fails run an angle grinder down the disc & cut the disc off.

[gregs656]

I have had to do this once - I used an over sized, sacrificial torx bit and hammered it into the rounded hole. Suggest holding the bit in place with a ring spanner so you can really go to town on it.

[Huff]

Put a 6mm HSS drill down the middle of the thing. Once you're into teh threaded portion the head will shear-off easily with a tug on the disc and it's the fastest way.

As noted above, you don't need to worry if you cannot then remove the stub.

[With these feet]

Hit the disc/bolt head square on with a hammer. No need to hit from the rear, several good blows usually loosens the bolts grip. If the head is still visible but damaged sometimes a torx bit will knock in. If youve freed it off sufficiently it should come out. A little heat can sometimes help.

[kev b]

An old trick is to take a centre punch and strike the screw next to each flat, this should squash the head enough to help an allen key grip.

An impact driver will do the trick as well if you can borrow one but the simplest way is to drill the head off and replace the screw.

[helix402]

You won't ruin the bearing by hitting the disc from behind with a hammer. The disc will break and you can remove the bolt. Or just take the bolt out first using one of the suggested methods.

[roofer]

Hammer a torn bit into it. Job done.