Help! Front brake threaded sleeve stuck in fork crown

on-yer-bike

The threaded alu sleeve that the front brake caliper screws into is stuck in the carbon fork crown. Ive tried screwing in a bolt from the front and tapping it out but it wont budge. Ive also tried soaking it Coke. Any other suggestions?

sungod

if it's corroded it'll be pretty tight, the phosphoric acid concentration in coke is quite low and the contact area small, it'd take a long time to do anything

i'd avoid trying to dislodge it by hitting it, doesn't it have a hex recess in it? rotational force should be gentler

freezer spray on the nut might loosen it, it'll contract much faster/further than the surrounding cf

you could use a more aggressive concentration of phosphoric acid, for instance some cleaners/descalers are c. 50%, but make sure you take suitable safety precautions and ffs don't mix it with other cleaners/solvents, if you need to dilute it, drip it into cold water (not the other way around!)

on-yer-bike

sungod wrote:

if it's corroded it'll be pretty tight, the phosphoric acid concentration in coke is quite low and the contact area small, it'd take a long time to do anything

i'd avoid trying to dislodge it by hitting it, doesn't it have a hex recess in it? rotational force should be gentler

freezer spray on the nut might loosen it, it'll contract much faster/further than the surrounding cf

you could use a more aggressive concentration of phosphoric acid, for instance some cleaners/descalers are c. 50%, but make sure you take suitable safety precautions and ffs don't mix it with other cleaners/solvents, if you need to dilute it, drip it into cold water (not the other way around!)

The hex hole has rounded. Ive tried filing it out too. What is freezer spray. Have you a brand name?

mrdsgs

longer bolt from front that is only threaded part way. three it into the stuck bolt until it bottoms out, then gently keep trying to turn it, logically it should force the recessed sleeve/nut to rotate/come loose. Then whack the bolt with a gentle hammer!

sungod

there're many brands/sizes, for instance...

http://www.maplin.co.uk/p/servisol-free ... 00ml-re77j

mamba80

if you screw in a long threaded bolt into the stuck one (from back of fork) with a washer and nut on first.

then hold the bolt head with a spanner, whilst with another spanner tighten the nut against washer and fork (you ve made a simple puller) the threaded insert will have to pull out, u might need to make up a tube to fit between fork and nut/washer so insert can come out all the way.

does that make sense?

Monty Dog

Find suitable M6 bolt/screw - insert from the front and screw-in a few times to engage the thread but leave the head protruding. Hit firmly with a hammer. Coke/phosphoric acid does nothing for aluminium oxide corrosion except make it sticky - you need an alkali.

sungod

Monty Dog wrote:

Find suitable M6 bolt/screw - insert from the front and screw-in a few times to engage the thread but leave the head protruding. Hit firmly with a hammer. Coke/phosphoric acid does nothing for aluminium oxide corrosion except make it sticky - you need an alkali.

advising someone to hit a safety critical composite component with a hammer?

phosphoric acid is a standard method for removal of aluminium corrosion (for instance, standard MIL-C-38334)

which i why i suggested cleaners/descalers based on it in the event that gentle mechanical/thermal methods didn't work

on-yer-bike

thanks for advice. I cut two grooves with a dremel and needle files then inserted a large screw driver bit on a ratchet handle and mangled the sleeve. it then tapped out easily with a bolt and a mallet. ive put a slight groove in the carbon but hopefully its okay. its a deep fork crown and the sleeve is very long and completely covered in white corrosion. it took me hours.

on-yer-bike

Ive just purchased a Wheels Manufacturing stainless version form Malcolm at the Cycle Clinic.

Semantik

Never needed a chemistry set to remove one of these in my life.

Just get a masonry drill bit of the right diameter, insert it through the hole from the front of the fork then give it some strong taps with a hammer. You will only damage something in the process if you are a cack-handed gorilla.

on-yer-bike

Semantik wrote:

Never needed a chemistry set to remove one of these in my life.

Just get a masonry drill bit of the right diameter, insert it through the hole from the front of the fork then give it some strong taps with a hammer. You will only damage something in the process if you are a cack-handed gorilla.

It wouldnt budge after repeated tapping. Ive heard that a lump of carbon can come out with the sleeve. Its 40 mm long and completely covered in white corrosion. Not sure what the replacement cost is for a Colnago c59 fork. :shock:

ugo.santalucia

Why do you need to remove it?

keef66

Reading between the lines he'd rounded the hex socket but removed the caliper by unscrewing it from the fork.

Mine all come off once a year for a clean and a spot of grease just to be sure...

Monty Dog

Appears to me that some people think that carbon is like glass and will shatter into a thousand pieces, but making a part in aluminium alloy and sticking it in a place where where it's highly prone to corrosion isn't exactly clever either - it's not like galvanic corrosion is a new phenomenon.

Semantik

on-yer-bike wrote:

Semantik wrote:

Never needed a chemistry set to remove one of these in my life.

Just get a masonry drill bit of the right diameter, insert it through the hole from the front of the fork then give it some strong taps with a hammer. You will only damage something in the process if you are a cack-handed gorilla.

It wouldnt budge after repeated tapping. Ive heard that a lump of carbon can come out with the sleeve. Its 40 mm long and completely covered in white corrosion. Not sure what the replacement cost is for a Colnago c59 fork. :shock:

Just 'tap' it a bit harder.

Or if you are worried about not striking it square on then wind the brake caliper part way back into it then hit a piece of wood held against the front of the caliper. It's only crud holding it in place- it can't have fused with the carbon fork or anything silly.

keezx

This

Wat you need is more "persuation"....

Whack it out with either a 6 mm bolt screwed in the nut or an old steel 8 mm drill bit.

on-yer-bike

It had fused with carbon fork