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JB Weld for bike repair(14 posts)

JB Weld for bike repairsharkey
Aug 20, 2003 12:31 PM
I have a top brand FS aluminum mountain bike (I'll tell you the brand if you REALLY want to know) that has recently run into a warranty issue. I was wiping down the frame after a muddy ride the other day and one of the cable stops on the downtube came right off. I've never even heard of this happening!! The only thing I can think of is that it was a tack weld that was never fully welded. In any case, I'm not looking forward to what promises to be a very long, drawn out warranty procedure (tearing down the bike, sending it to California, waiting, waiting, waiting). I've asked a couple of local TIG welders if they could just weld it back on . . . they said they'd prefer not to because unless the factory strips the whole frame and repaints it, it looks like a mess. Their suggestion was that I try using "JB Weld" . . . a super-strong metal epoxy. Apparently, this stuff has a tensile strength of something like 1800 PSI, and while I would never use it to fix a broken head tube or suspension swingarm, it might do the trick to put this cable stop back on. Anybody have any experience with this stuff??

Thanks in Advance

One more note: What good is a warranty if it is so difficult, expensive and time consuming to collect on?
I don't think so...spluti
Aug 20, 2003 12:45 PM
The strength of the glue joint is proportional to the surface area covered. JB weld is amazing glue but I don't think a cable stop allows you a big enough foot print for a good bond. What happens if it fails at the wrong time?
Clamp on stops ??MR_GRUMPY
Aug 20, 2003 1:03 PM
I seem to remember someone selling a clamp on stop for people converting from canti's to V brakes.
no problem...merckx56
Aug 20, 2003 1:08 PM
Back in my days of wrenching in a shop, we fixed a couple of very high end road frames with the same problem you have.
JB Weld worked perfectly and no one was the wiser. Just be careful when doing it and it should be just fine.
Wonderful stuff ... tested it in the lab ...Humma Hah
Aug 20, 2003 1:19 PM
I did materials science for about 15 years, and we used some of the best construction epoxies made. JB Weld is as good as any and better than most, and has some properties that are pretty special.

1800 psi? I'd personally trust a well-prepared joint, steel to steel, to at least 3000 psi, tensile or shear, and would bet you could hit about 12,000 psi on a grit-blasted steel surface, in tension.

It was designed to repair engine blocks, so can handle heat. But the really remarkable property it its ability to handle cold. Some tests require epoxying test samples into the fixtures, and to remove the epoxy after a test, I would usually chill it with liquid nitrogen and it would pop right off. Then I tried JB, and the stuff just sat there under gently bubbling LN2, cold as I could get it, with no loss of bond adhesion.

It has a special affinity for steel ... I don't have as much experience with using it on aluminum, but it should be OK for gluing on something that won't be dangerous if it breaks loose. So it depends on what this cable stop stops.

However, there are shops that specialize in applying things like braze-on brake bosses, that do minimal damage to the paint, and then re-touch it like new. They could probably fix your machine just fine.
That's the slow-cure JB, not JB-quick ...Humma Hah
Aug 20, 2003 1:41 PM
Don't try this with JB Quick. The slow-cure formula gives it time to form the really assertive bond. The quick-cure stuff will pop loose at a small fraction of the load the normal stuff will handle.
Don't they have a specific formula for Aluminum???NMspluti
Aug 20, 2003 1:46 PM
Their website doesn't show one ...Humma Hah
Aug 20, 2003 3:31 PM
... but the basic product, AdhesiveWeld (sold as JB Weld, Industro-Weld, Marine Weld, and several other names) is listed as bonding to a whole slew of materials, including most metals. It contains finely ground steel. They give the tensile strength as a little over 4000 psi.

I've got one machine in which I bonded a bronze gear to an aluminum plate with JB. Due to differential contraction of the two metals, I calculated that it should stand about -20 C before the joint broke, based on a 3000 psi shear strength. In fact, it broke the epoxy bond at about -27C about a month ago when I got the machine colder than I intended. So it works pretty well on aluminum.

I've seen it go WAY past that with steel.
LN2 and Gummi Bears...PdxMark
Aug 20, 2003 4:31 PM
There were times in graduate school that we tended to experiment outside our usual fields of study. One test was to drop Gummi Bears into liquid nitrogen to see what happened. Not much while in the LN2, but drop a Gummi Bear on the floor afterwards and it would shatter. Made quite a mess.
Go for it but...the bull
Aug 20, 2003 6:17 PM
make sure the frame company wont use it as an excuse to void the warranty of the frame or that problem.You know how this could go!
.....if it's an Elsworthdivve
Aug 21, 2003 2:26 AM
Get it warranted quick, because the lifetime warranty ends when they update your frame and have no old stock (which coincidentally they never have).
Thats what happened to me.the bull
Aug 21, 2003 3:46 AM
They suck!
They bikes ride awesome.
I had to pay a grand to "upgrade" to the new frame(because the headtube cracked).
Delivery still took over 2 months because they shut down for interbike.
They said it would be the "quickest way to get a rolling agian".
Tony Ellsworth said I was lucky to get a new frame because he had paying customers waiting to get his frames.
I guess one the frame is delivered your not a paying customer huh.
I had To replace a swing arm once and it was not so bad.
it's amazing those guys are still in business.... nm.divve
Aug 21, 2003 6:31 AM
Probably more appropriate on mtbr.com, but here goes...Roadi
Aug 21, 2003 8:07 AM
I have 4 friends here in San Diego that he burned. Never buy anything from Tony Ellsworth. I met him once at Big Bear and I found him to be an arrogant prick. He will run himself out of buisness.