Help: rounded front brake bolt :/

bwilks

i have a look 586 frame

dura ace 7900 front brake

the fixing bolt which fits through the fork from the back and allows the brake to screw into it has rounded

the brake is sitting 5mm proud of the front of the fork. still attached but wobble from side to side as it is not tight

cant get very good purchase on the bolt from the back as the brake is still quite a bit in it

ive tried spinning the brake itself but it just spins with the bolt

can anyone help
the only solution ive come up involves a hacksaw and i really dont want saw a dura ace brake
thanks!

Wirral_paul

I assume it is a 5mm allen key fitting that is rounded? If so then you could try and tap a torx bit into the nut. Some penetrating fluid or gt85 will usually help

nicklouse

If you can't get purchase on the bolt change your tools so you can.

You say the brake is proud at the front? Then press it in to push out the bolt a bit?

bwilks

the bolt is stuck on the front brake mount if that makes sense

so if i push the brake in it just moves the mount with attached bolt further in ( i need to get them apart)

the position of the bolt on the brake mount (bit that pushes into the frame/fork) isnt changing

the nut is a hollow cylinder which the brake mount screws into as such there isnt anything to tap into.
the thing i would be tapping into would be the brake mount spindle

dee4life2005

I've just gone through exactly the same scenario with an ultegra 6700 front brake. I've been using my road bike regularly over the winter, and not given it a full strip down in a while. The front brake was solid, and attempts at undoing it were just rounding off the bolt head, which you can't get to easily on my bike as it sits recessed in the fork by about 4-5cm.

I tried flushing it out with Muc-Off, GT85 etc. It flushed out loads of muck, that must have been preventing the allen key getting good purchase on the bolt.

It did manage to get it off in the end, thankfully, but it wasn't easy.

I have a carbon fork, and had to very very gently tap the allen key into the bolt (using a rubber mallet) so that it got slightly better purchase on the head of the bolt. Then, instead of turning the allen key, I held that fixed and used the calliper itself to unwind it from the bolt. It took a few goes but it did eventually come off. Managed to source a new hollow cylinder bolt from SJS and it's properly sorted now.

best of luck.

desweller

Shine a torch into the recess and make sure there's no sh1t in the screw head for starters. Whip the pads and wheel off and douse the whole area in WD40 or Plusgas (take care not to allow any into the crown headset bearing). Use good quality hex or torx keys. Try imperial sizes if you get nowhere with metric ones, but you may need to persuade them into place with a mallet.

jermas

If the head of the brake nut is proud of the forks, you could cut a slot in the top of the nut (if there's enough clearance),then use a large flat screwdriver to hold the nut. This has worked for me, but I used an impact screwdriver. If not, and there's enough depth in the nut, a bolt extractor might work.

bwilks

thanks for all the responses.

there isnt really any room to top an allen key in, the brake spindle is right into the nut, if i was to tape an allen key i would be tapping the allen key into the spindle of the brake and possibly damage the threads

- that said i may just have to try that anyway

not sure what you mean jermas.... the brake is sitting out from the fork and is not flush with it as it should be.
if i spin the brake the nut inside just spins with it

aww mannnnnnnnnn

i just assumed this has happened a milion times before and someone was going to suggest the really simple obvious method that i couldnt think of lol

nicklouse

Looked at the exploded view?

http://techdocs.shimano.com/media/techd ... 713523.pdf

Got any ideas?

desweller

You won't damage the screw. You won't be striking it hard enough.

Semantik

bwilks wrote:

thanks for all the responses.

there isnt really any room to top an allen key in, the brake spindle is right into the nut, if i was to tape an allen key i would be tapping the allen key into the spindle of the brake and possibly damage the threads
/

There WILL be room to tap an allen key in otherwise it wouldn't have been possible to get an allen key in there to tighten it against the caliper spindle(pivot bolt) in the first place.

Yet you also say the caliper is 'sitting out from the fork'- this would suggest that the pivot nut has been partially loosened and backed off already so the problem is probably not as serious as you think.
Some pics would be useful but I suspect it is not as difficult to remove as you think- Deeforlife has used a method that has also worked for me many times- suggest you try and solve it along the same lines.

Avoneer

Hi,
Torx tapped in would be my weapon of choice.
Pat.

rafletcher

I'd hacksaw through the bolt and get a new one.

pinarellokid

Tap a torx in it will sort it out I'm sure as a torx grabs the corners where it isn't worn

bwilks

im trying to avoid hacksawing a dura ace brake. can you buy replacement bolts? or does the hacksaw method leave the brake bust ?

is a torx a hex key? as opposed to an allen key?

i will go for this option when i get a second

desweller

Torx is sort of star shaped. A quick wield of your search engine skills ought to show you.

Avoneer

If you're anywhere near Bacup, you can fetch it round and I'll have a crack at it for you.

Pat.