Bolt jammed in carbon forks?

[criefftony]

Hi folks. I'm hoping I've missed something obvious here...
I've just picked up a second hand frameset (Boardman carbon)
and I'm swapping over a veloce groupset from my old bike.
Problem is with the front brake - there seems to be a bolt already in the fork.
Allen key (not bolt) is just spinning when fitted in the rear.
I've screwed a bolt in there and given it a few hard taps but it seems really solid.
Any ideas?

[Brucey]

if the old allen key nut fitting won't come out (eg through corrosion) then I'd suggest dousing it in penetrant and then try to find a way of mounting a brake without having to disturb it.

For example you could screw the new brake into the trapped nut wholesale, and pack it out with the right thickness of washers so that it is tight enough when the brake is centred.

Unfortunately brute force and CF are not happy bedfellows, so if you try to remove the trapped nut you may scrap the fork.

cheers

[criefftony]

Thanks BruceyI kinda guessed that.
Suppose I was just hoping I'd missed a nice easy solution.
I'll give it a soak tomorrow
Fingers crossed
T

[Valbrona]

All you do is thread a hex wrench through the other side of the hole and gently tap the end with something ... and out it pops.

Alternatively, you get your front brake, insert the main fixing bolt like you would if you were mounting the brake, twizzle the caliper around a few times until some threads are engaged, and tap the caliper with a rubber mallet.

Carbon fibre is a pretty resistant material, but use the wrong penetrant and is can dull the lacquer that is applied over paintwork. We are talking a jammed nut and not corrosion.

[criefftony]

Thanks valbrona
I've tried all that. Even screwed in a long flat head bolt and given it much more than a gentle tap.
In fact I bent the bolt. It is very stuck!
I'm going to pack it with washers so it tightens to roughly the right position and give it a try.

[cycleruk]

Allen key (not bolt) is just spinning when fitted in the rear.
I've screwed a bolt in there and given it a few hard taps but it seems really solid.
Any ideas?

Allen key spinning?
Does that mean the hexagon inside the nut is rounded off.?
An option would be to drill it out but could be a problem if it started spinning.

Perhaps fit a long bolt locked in from the front then if the nut does start spinning, while drilling, the bolt should hold it.
If you drilled off the nut head then the bolt would pull the rest of the nut out.

If there is a Halfords in your region you could ask their cycle expert about it.

[criefftony]

yes - the hex in the bolt head is rounded off
(I guess the previous owner had a good go at it too!)
I've got it set up pretty close using washers - if that doesn't work I might try drilling.
the rounded hex should provide a good guide hole to drill down near to the shoulder.

I might pop it in to Halfords just for the entertainment value?
Thanks for all the ideas

[Brucey]

the problem with drilling metal fittings that are lodged in CF is that the fitting gets hot and the CF tends to get melty or otherwise distressed. And when you have run the drill through you can still be left with a (now threadless) metal sleeve jammed in the part.

Whilst it would irritate me if I have a brake bolt I couldn't undo, it'd be much, much worse if I wrecked the thing, having already been able to at least set the bike up so it works...

BTW if you need very thin M6 shim washers, the LBS should have them for setting up disc brake calipers. They should work here, too.

cheers

[Valbrona]

Okay, might sound stupid, forgive me ... Are you sure it is a brake nut that is lodged and not some kind of aluminium insert where the brake nut sits? Not that I have ever seen some kind of aluminium inset in a carbon monocoque fork. And are we talking full carbon fork or something with an aluminium fork crown?

[RonK]

Sounds like a captive nut.
Insert caliper from front, allen key from back, tighten.