expander bung

[ehelifecycle]

Does anyone know how to get this expander bung out of a set of carbon forks, I have tried

hope you can help

[Brucey]

normally if you back the (8mm allen key) bolt out about a turn and a half, and then give the bolt head a light tap with a small hammer, the bung will come loose. This usually works well if the bung is a conical wedge type.

Obviously it won't work at all if someone has bonded the bung in with epoxy resin or something like that.

Some bikes have been (as a factory recall) fitted with bonded bungs or sleeves in the steerer; do check that your bike/fork doesn't have a recall or mod on it.

BTW why do you want to remove it?

cheers

[Gattonero]

I would removed it to have that steerer cut at 90º, not as it is now

[andrewjoseph]

sometimes with the hope head doctor expander bung on my bikes, i need to apply pressure to the underside to stop the hex bolt just turning.

Is that a carbon steerer? seems to be an conical insert from top of steerer down to bung, or is it just the light reflections?

[ehelifecycle]

normally if you back the (8mm allen key) bolt out about a turn and a half, and then give the bolt head a light tap with a small hammer, the bung will come loose. This usually works well if the bung is a conical wedge type.

Obviously it won't work at all if someone has bonded the bung in with epoxy resin or something like that.

Some bikes have been (as a factory recall) fitted with bonded bungs or sleeves in the steerer; do check that your bike/fork doesn't have a recall or mod on it.

BTW why do you want to remove it?

cheers

I want to sell the forks

[ehelifecycle]

sometimes with the hope head doctor expander bung on my bikes, i need to apply pressure to the underside to stop the hex bolt just turning.

Is that a carbon steerer? seems to be an conical insert from top of steerer down to bung, or is it just the light reflections?

It is a carbon steerer

[ehelifecycle]

normally if you back the (8mm allen key) bolt out about a turn and a half, and then give the bolt head a light tap with a small hammer, the bung will come loose. This usually works well if the bung is a conical wedge type.

Obviously it won't work at all if someone has bonded the bung in with epoxy resin or something like that.

Some bikes have been (as a factory recall) fitted with bonded bungs or sleeves in the steerer; do check that your bike/fork doesn't have a recall or mod on it.

BTW why do you want to remove it?

cheers

when i turn the 8mm allen key bolt the whole lot spins, not easily but it will rotate however there is no way to pull as i turn. i thinking that if i can get some penetrating oil between the carbon and the bung then it might edge out. what do you think?

[Brucey]

I think the bolt is stuck in the wedge piece, and that is why the whole thing is turning. However if the whole thing is turning, I'd have said that it ought to come out. Have you tried (carefully) using an M6 bolt as a 'puller'? If nothing else you might be able to jam the wedge back together and then you may be able to back the aluminium bolt out a bit more.

cheers

[tim-b]

Hi
Unless you're very careful, all that you'll achieve is to damage the inside of the steerer
I would sell the fork with the bung, top cap, etc. as that one seems (from the photos) to have the 8mm expander bolt incorporated into the top part of the wedge assembly. If the steerer fits the buyer's needs then it's not a problem, if the steerer needs to be shortened then a carefully wielded hacksaw might give you the access that you need to remove the bung, just hope that it's not bonded in/some bizarre standard

If you need an expander bung for another project find one with a separate expander bolt

Regards
tim-b

[andrewjoseph]

This sounds like the problem i have with the hope bung. i use a long allen key from underneath to apply pressure upwards as i loosen it from the top.

the top of the steerer has this conical (metal?) insert. can this be removed? if so then maybe a screwdriver can be used to hold part of the bung in place while loosening.

[Brucey]

unfortunately very many carbon forks have no axial drilling through the crown, thus there is usually no access to the underside of the bung assembly.

cheers

[andrewjoseph]

unfortunately very many carbon forks have no axial drilling through the crown, thus there is usually no access to the underside of the bung assembly.

cheers

so then taking out that 'cap' (if possible) and using something else to stop rotation, might be the only other way.

[andrewjoseph]

unfortunately very many carbon forks have no axial drilling through the crown, thus there is usually no access to the underside of the bung assembly.

cheers

so then taking out that 'cap' (if possible) and using something else to stop rotation, might be the only other way.

Also, i'd advise against using any form of oil in the carbon steerer as this may have a detrimental effect on the laminate.

[Brucey]

the whole point is that the cap is part of the bung and the OP can't get it out....

If the OP really wants to get the thing out -come what may- then there is always a way.

Presuming that it is a wedge type bung and the wedge is loose enough to spin on the hollow bolt (which is partially seized in the wedge) whilst not being loose enough to allow the bung to come out (hard to imagine but that is pretty much what the OP is saying) .... then you need to drill a couple of small diameter (~2mm) holes through the bung so that they clear the head of the hollow bolt, but do go into the wedge piece.

Then stick a couple of old spokes down the holes, and swing on the 8mm hex head of the hollow bolt. Now it ought to come undone and release like it should have done in the first place....?

cheers

[andrewjoseph]

the whole point is that the cap is part of the bung and the OP can't get it out....

I don't think it is. there is a hole through the cap for the Allen key. there is a slight gap between edge of steerer and the cap.

I've never seen one before and it may be that the whole point of the cap is to stop the bung pulling out.