damaged my boom...help, doug!

[Andrew 1973]

I was in the middle of overhauling my Silvio when disaster struck. In removing the sealed BB, it was siezed and wouldt budge. I used a Campagnolo BB tool with a wrench and cheater bar with a good soaking of PB Blaster on the BB.

I heard a loud metallic crack and the BB began to unthread. I felt victorius until while cleaning the threads in the shell, I could see a glimmer of daylight where the weld is the crack isn't wide, but is about 3/4" long. I know extra parts aren't always readily available, so I need helpw finding a solution. I am hopeful that Doug knows what to do.

Can the crack be spot welded by a professional who knows aluminum?

 

[flashburn]

Pictures might be worth a

Pictures might be well worth posting.

 

[Andrew 1973]

I'll give.that a try

I am no photographer and getting the crack to show up isn't easy. When I get home, I will try again.

 

[Doug Burton]

Photos are indeed needed...

I need to see the crack so I can see if there's a remedy short of replacing the boom, which may be a challenge at this point.

Not trying to be rude, but I've seen a lot of bike parts (and car parts) damaged with extra leverage.

General rule on these bikes:

There's nothing on any Cruzbike that should require a cheater bar to remove it. Most of the parts are aluminum (aluminium) and they yield suddenly when limits are exceeded.

I am reminded of what a British car mechanic told me back when I had a Triumph Spitfire: "If it's hard, you're doing it wrong." (Unfortunately on those old cars, I was usually doing it wrong )

Aluminum and other metals (particularly steel) in threaded contact develop a great deal of affection for each other, particularly if water is available. There is an ionic exchange that occurs, and sometimes the parts can effectively weld to each other. Unfortunately, in the case of steel BB bodies and aluminum BB shells, this is reality. I always lubricate BB shell threads prior to installation with waterproof grease to the point of making a mess.

So what to do? When I encounter a stuck bottom bracket, the first thing I do is heat the BB shell area with a heat gun to where it's very uncomfortable to touch - if I had to guess I'd say 140 - 160 F. This causes the differential expansion rates of the two metals (aluminum expands more rapidly than steel) to break the chemical bond that may have formed, and to slightly separate the parts. Then, in the case of a boom/bottom bracket, I put the BB tool in a large vice and gently apply a pulsing pressure to the boom end. Yes, it's a little like using a cheater bar, but if you're sensitive to any movement and don't try to take it all off in one turn, (And remember that one side uses reverse threads!) it will usually let go.

I've run into several stuck BB's on Sofriders, partly because when they were torqued the shop was very warm and the BB shell contracted after the bike was shipped to a colder environment.

I know this sounds like a lecture; it's not meant that way. Just trying to take this opportunity to inform folks. If we can help you, we certainly will do so.

 

[Ivan]

Photo Tips

Hi Andrew, sorry to hear that. I can't give repair advice but I can offer to help with regards to your photo. Set your camera to "macro" mode. Even on basic point and shoot digital you will have this. This mode is frequently indicated with a "flower icon" - it is the mode for close-up pictures. If you have a zoom, then zoom in a little but not all the way. This will allow you to be a bit further away from the subject which is better for focus and light. Turn off your flash on the camera and try to have lots of ambient light. Out in daylight would be excellent. Of course, keep hands very steady, resting on something if possible.

When you upload the images feel free to also email me your best photo in full size (ie. the original large file). I can try to photoshop it and bring out the details so that Doug can see more clearly, then repost on this thread. The black is not easy to see the details, but Photoshop can often bring out the details that are there. You can send to me: iliew(at)wefc.org.sg

 

[Andrew 1973]

thanks, doug

I appreciate your knowledge and your in depth explanation. I do want to say that, like you describe, I used a pulsing motion to break the part free. I liken it to "bouncing" the cheater bar slightly in anticipation of that moment when the part breaks free. I certainly don't want to give the idea that I used brute force with a long lever. As a matter of fact, I recently tried to remove the pedals from a brand new bike, but stopped as soon as my Park pedal wrench began to round over the flats of the pedal spindle. I took the bike to the shop and before the mechanic touched it, he rather rudely insinuated that I was turning the wrench the wrong way. Rather than argue, I just let him try. He certaonly had his work cut out for him and the pedal did finally release with a loud CRACK as it finally break free. This was an alloy crank arm with a steel pedal spindle; a similar interface to the BB and shell, but in this case it was on a brand new bike. I assume that this was a matter of the pedal having been over-tightened to begin with.

The BB was not, as I believe, over-tightened or improperly installed. The threads look fine, but have a hardened, whiteish oxidiation layer. This Silvio is an early one and has seen more miles than I could guess and has been ridden well beyond my ability. But even as a humble commuter and occasional fast recreational rider, I have subjected the bike to less than ideal conditions (think wet).

My desire is to have the boom repaired to preserve the integrity of this Silvio, and with the fact that it is unlikely that spares exist, it is even more so important to repair over replace.

 

[Doug Burton]

No worries, Andrew...

... We will get you taken care of, one way or another. We have options, and we'll do whatever it takes.

I know you have sensitivity to the parts; sometimes our skill at recovery gets exercised. I just want folks to think a little before they break things, and this is an acquired skill, involving lots of cussing and throwing things...

I can't tell you how much stuff I've broken. In my "day job" I get paid to break stuff, nowadays. It ain't bad duty, really.

Cheers,

Doug

 

[Andrew 1973]

good point

With the specialized nature of these bikes, I don't mind being made into an example if it keeps others from damaging their Cruzbikes.

 

[gwoodbridge]

Should we use Anti-Seize Compound for BB install?

Doug,

Should I use ?Anti-Seize Compound to install the Shimano Ultraga BB into the Vendetta then?

Thanks,
Gary

 

[Jerrye]

I could be wrong, but...

I have always been told to use something to prevent seizing when joining threaded dissimilar metals. So I would think your suggestion would be spot on Gary...but listen to Doug on this, not me!

 

[Doug Burton]

Anti-seize

... and bikes and I haven't gotten along all that well.

I've always gotten good results with Phil Wood Waterproof Grease, and it has lots of other uses. Stays put where you put it and wipes off of paint without attacking the clear coat.

I apply it with a small flat painter's brush.

Anti-seize would probably work fine though...