Bicycle Mechanics - STUCK - Burley Tandem Bottom Bracket
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03-23-11, 06:34 AM
Last week we picked up a nagging noise in the drive train. We were out of town on spring break and, though the bike shop couldn't fix it, they did isolate the noise as coming from the stoker's bottom bracket.
Burley used a proprietary bottom bracket setup with two sealed bearing held in place with snap rings. Tandems East had the bearing and snap rings to replace. The rings came out with no problem. But the bearings and spindle won't move.
I've been soaking it with PB Blaster (that's the liquid you see in the picture) and using a dead blow hammer and pvc pipe to hit the bearing rather than the end of the spindle.
I'm actually considering building a puller that would tap into the spindle and press against the frame but that seems like overkill.
Am I missing something here? Any ideas on what to do next?
03-23-11, 07:27 AM
Seems like you would hit the spindle to knock the other side loose, then switch? Or improvise a puller using the spindle threads as you mentioned.
03-23-11, 08:47 AM
Be careful about Tandems East. I talked to the owner, Mel, emailed him the page with the part that I wanted, paste/copied the item name off his website, and he sent me another part that I did not order and now refuses to accept a return. So I have a part sitting in my drawer that I can't use. He said where did you get that description from, I told him I copied it off his website. And he won't sell me the right part now even if I pay for it. They are great on taking your money but not great on accepting responsibility for sending the wrong part.
You shouldn't try to hammer out a bearing using PVC pipe as a drift. It absorbs the energy peaks you need to break the part loose.
Also, on that type of BB you want to drive the bearings out, so start by supporting the frame on a piece of tubing or pipe that matches the BB shell, and drive the spindle which in turn will push out the backside bearing, then slide a piece of shaft through the shell and drive out the remaining bearings.
The key to effective hammering is to properly support the non-moving part against something with high inertia so the impact energy of your hammer isn't absorbed by stuff back from it.
To understand how effective good support is lay a piece of scrap wood on a workbench and hammer a nail in. Now hang the same piece over the edge and try again.
03-23-11, 11:22 AM
I have the same BB , built up a touring bike frame within the same part of town
as the Burly build shop so borrowed components
Best , an Arbor Press ... a machine shop tool, hydraulic jack
or gear advantage and a long lever.. for the pressure.
[not hard to scratch build .. if you have a machine shop]
there is just a bit of loc tite, on the bearing edge,
after you pop out the snap rings.
the bearings are standard, I got the ones for the build at a Eugene Bearing supplier.
part number should be an imprint on the seal.
03-23-11, 03:30 PM
I don't have a machine shop but do have a forman who is pretty handy with such. I figured a long bolt, two nuts, and some sort of U-shaped piece of steel to press against the BB, with a hole in the bottom for the bolt, would do it.
03-23-11, 03:41 PM
What is the thread size for the crank fixing bolts, i.e, to thread into the end of the spindle?
03-23-11, 03:45 PM
Need to support the frame around the edge [not bung up the paint] and press on the bearing itself .
there is a sleeve of aluminum between the bearings and around the axle.
wouldn't fare so well banging on it.
Loctite has been made to break it's bond with heat , so a heat gun may provide some.
Arbor refers to the crossbar of steel supported by 2steel uprights which are also firmly bolted to the base
But making something out of heavy timbers may do 4x4,4x6,etc.. carriage bolts ..
then you use a Hydraulic car jack to push on stuff , a steady increasing force ,
rather than sharp spikes of force like from a hammer.
Use the poor man's bearing press.
Use a piece of pipe, or U-bracket to support the BB shell, use a piece of flat scrap to protect the face of the spindle. Load the setup into a good sized bench vise and crank down.
Be sure everything is squared up properly, and wear protection lest the arrangement jumps under pressure. This is more of a risk with the U-bracket than a piece of tubing which would stay trapped by the spindle.
03-23-11, 04:09 PM
probably a 3 person job on a tandem .. a bit long and unwieldy ..
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