Getting brake posts off with brute force

[Rik]

Oh I love brute force, that, combined with using inappropriate tools/methods, makes me go all wet and stuff.
Today I had to swap disc brakes on to a bike that was running V's. In the process, had to swap the brake posts between bikes too... I would've just changed the forks over, but the steerer length differed by 50mm :roll:

So... to remove the posts from one fork took 90 minutes, unbeleivable, in this time we did everything... firstly rounded them out with a standard spanner Then the vice grips wouldn't grip enough, so threw the forks into the big vice. The alu jaws wouldn't grip either. This was getting frustrating... I found the brass axle clamp, and even with that tightened up in the vice with all my might, it was barely getting enough grip on the brake posts to stop it spinning with the fork.
Ugh, anyway, we ended up getting the posts out, albeit they were rather squashed.

So... we needed replacement posts, thankfully we had a dead fork of the same brand lying around to use for parts. I brought it home and gave it some Rik loving.

I've done this on my own frames, it's very much a last resort method and you have to be extremely careful when doing it... so what is this fantastic method?
BLOWTORCH THE BASTARD.

A La:

I have a basic propane torch, safety glasses (important), a lighter (very naughty, should only use matches), spanners to suit, and just in case, vicegrips on hand.

So... heat up the brake post, trying as best you can to direct the flame at the post only, you don't want to heat up the surrounding area, especially if it's a lightweight alu frame. The tip of the blue flame is the hottest part, so aim to have that right on what you want to heat up.
This one was more than hot enough:


So I grab the spanner, give it a bit of a budge... it moved slightly with a fair bit of force


Kept on heating it up slowly, being very careful, and trying to get it moving again.
Finally it started spinning...

And Voila, we've removed the brake posts. This is a very silly thing to do so you have to take responsibility for your actions. It works, I've done it a few times, but I cannot stress how careful you have to be to not scorch your paintwork or burn anything surrounding the posts.
If you don't pay attention, you end up with things smoking when they shouldn't:


So... that's my little tech tip for tonight, after getting all worked up about brute forcing it, I think I need to have a cigarette to calm me down... ohh yeh baby, I hope it was good for you too.

 

[lotec]

whoah cool do you know what material those brake posts are made out of to turn the flame pink that looks so cool i know copper turns flames green but PINK

 

[Avanti_Racing]

good istructions and all but a hacksaw will work fine, find the middle of the forks vertically and saw away

 

[Archi]

whoah cool do you know what material those brake posts are made out of to turn the flame pink that looks so cool i know copper turns flames green but PINK

in the movie 2fast 2furious, th cars shoot out pink flames from the nitrous oxide. :lol:

also, i'm not sure about this ,but i saw in a car magazine that heat turns titanium mufflers blue. 8)

 

[_J_]

rik knows everything

 

[Cúl-Báire]

RIk your a mad bastard!.. Cant blame you though, Pulling the studs out of the Psylo's was a long and rather annoying task, did have to resort to heating though.

RIK WE SALUTE YOU! *Waves 12" shifter in the air*

 

[Mason]

Haha, thats awsome Rik, fire solves all the problems when things are made of metal.

 

[BenM]

I wouldn't do this.

(1) For starters - if you used a good quality RING spanner, rather than an open ender, you would probably have had no problems.

(2) If the post was loctited in, it is OK to heat up the loctite to break the grip, but you only need 300-400oC.

(3) you can seriously alter the strength and properties of the bolt if you don't know what you are doing.

(5) heating the bolt up will actually make it EXPAND - making it harder to get out. If you want to loosen it you need to heat up the thing the bolt is in - i.e. the fork. My guess is all you did bu heating it up was break the loctite bond. which you could have done just the same by heating to a lower temp further down.

 

[Rik]

(1) For starters - if you used a good quality RING spanner, rather than an open ender, you would probably have had no problems.

How do you do this, when there's only 2 flats on the post?

I'm aware of the rest, but how do you do it? I mean, sure, you want to break the bond, but do you want to heat up the surroundings too much? That's why I went for the hard and fast method, I'd rather overheat the bolt and get it out quicker than overheat say, an Easton Ultralite frame through heating the bolt slower at a lower temperature.
Is my thinking on the right track, or is there a better way, because I'd sure like to know...

 

[Daver]

rik- how the fuk did u manage to round out the brake post? i mean, i am a downer- yet i've never rounded one of those in my life- ever...

 

[Rik]

Easy... find a set of posts that are well and truly bonded into the fork, use a 9mm open spanner because nothing else will fit it, and turn... not that hard to do, it's a fairly common occurance with cheaper forks. But when even vice grips have issues turning them, then you know you've got a headache on your hands.

 

[fastrider gus]

i usually use an angle grinder.. they work well..

 

[Rik]

Not when you have to install the posts on another set of forks

 

[BenM]

(1) For starters - if you used a good quality RING spanner, rather than an open ender, you would probably have had no problems.

How do you do this, when there's only 2 flats on the post?

I'm aware of the rest, but how do you do it? I mean, sure, you want to break the bond, but do you want to heat up the surroundings too much? That's why I went for the hard and fast method, I'd rather overheat the bolt and get it out quicker than overheat say, an Easton Ultralite frame through heating the bolt slower at a lower temperature.
Is my thinking on the right track, or is there a better way, because I'd sure like to know...

OK - I didn't see that the 2nd set of posts were rounded - and why were they if they were a set that hadn't been touched? Did you round them trying to get them off before you resorted to heat???

Since the forks were spare/broken, using a bit of heat on them wouldn't hurt. And using a small amount of heat on an alum. alloy frame shouldn't affect it, so long as you only heat to approx 300 deg (enough to break any loctite that would be on a bike) and allow the alloy to cool down as slowly as possible.

And apart from a small amount of heating to break the loctite bond - heating the bolt will make it expand, making it harder to get out. The bolt is about 800 deg in your pic where it is red hot. If you want to do it this way, heat the bolt to break the loctite, then allow everything to cool completely and shrink back, THEN remove the bolt.

Personally, I have never had a set of brake posts that were difficult to remove - they shouldn't have been done up that tight in the first place.

 

[wombat]

OK - I didn't see that the 2nd set of posts were rounded - and why were they if they were a set that hadn't been touched? Did you round them trying to get them off before you resorted to heat???

They weren't rounded, that's just the way the posts are; they don't have a hexagonal profile, they are round with two flats on them, rendering a ring spanner completely useless.

 

[BenM]

OK sorry, never seen that type before - all the ones I have seen have a hex bolt at the bottom that you can put a ring spanner on - much more sensible.

You can get a special tool for clamping on and unscrewing threaded pipes without damage. It is a small bar with a foot on one end with teeth, and a chain that wraps around the pipe. Works much better than vice grips.

 

[FuTAnT]

[also, i'm not sure about this ,but i saw in a car magazine that heat turns titanium mufflers blue. 8)

I can vouch for that. I have a Fireblade with a Ti zorst and it's definately gone a lovely blue tinge. I managed to get the tip blue as well after an extented high speed jaunt, looks the shit.