Q: how do you know when the bottom bracket on your bicycle is about to seize up?
A: when your 40 minute commute gradually becomes 55 minutes...
The Scouts (some of the same lads Dan and I took to Saltspring last summer) did a trip down the Kettle Valley. Lionel G had purchased a fully suspended Dept. Store wanna-be-hucker for the trip. The bottom bracket began to seize up on him a few days into the trip. Kerry Newton led the trip, and as he is a professional --AUTO-- mechanic; he took along an almost complete toolkit.
What he lacked were some small but vital specialty tools for servicing newer MTB bikes...
I give Kerry credit for trying; however, hitting a crankarm with a hammer is not the recommended method for removal. The cranks got pretty banged up, and both crankarm bolts got stripped.
When the Scouts got back from the trip, Kerry contacted me and asked if I would be willing to try to repair the damage (both from the original fault and also repair attempts without the correct tools). I agreed to have a look at it, and warned Kerry that I might not have the correct tool if the bike was equipped with a cartridge-type bottom bracket. I am familiar with the procedure, but as none of my bikes have a cartridge BB, I don't have the tool in my toolbox. Kerry told me that he could cover both the tool and the repair if I could do it. I thought about it for a day or so, then Lionel contacted me on Sunday and I agreed. He brought the bike over. I think the reason he didn't just take the bike back to the store was because there was some damage to a shifter (outer shell broke off), and of course the hammer-marks on the cranks.
I got the cranks off no problem, but there was no way to get the cartridge BB out without a splined ISIS removal tool. I got a nice 1/2 drive IceToolz socket from Cap's on Tuesday...but I was so BUSY that day that I didn't actually get to the repair until about 9PM. I got the BB apart, and found...no lube whatsoever. Manufacturing error. The bearings were completely dry, and quite cooked to boot. The races had been reduced to shards of rusted metal and dust. I was quite lucky (and surprised) to find no damage to the bearing cones and the crank itself.
First order of business was assembling a working set of raced bearings. I found the necessary in my parts bin; and BOY am I grateful I spent that hour or so last spring sorting all the loose bearings in the parts cabinet! Finding two sets of clean bearings was no problem...
Got the BB packed with moly grease, installed the bearings and seals, then installed the cones and torqued the whole assembly up to spec. Now came the hard part: installing the new crank bolts in the damaged threads of the crank. I got the LH side in OK, but the RH side of the crankshaft was too badly damaged to fit the bolt. The bolt WOULD NOT go in without cross-threading. I only had the one bolt, and if it wouldn't go in then I was going to be spending another day on this job; purchasing a new crankshaft and re-re-assembling the bike.
I had one of those "now what do I do?" moments.
And the answer came...the "still small voice"...
SSV: "You need to chase out those threads with something".
Me: "Like what?"
SSV: "How about a tap from Granpa's tap and die set?"
Me: "Oh, ok...where is it?"
SSV: "Over there in the corner, underneath the socket set and wrenches."
Please bear in mind that I've NEVER used a tap and die set before. Granpa's set comes in a big blue metal tray with a latching lid. It is about 24 by 32 inches, and easily holds about 50 taps and dies, all packed in foam. It takes up so much space on the shelf that he stacked the other tools on top of it...
So I opened up the set and peered inside...having absolutely NO clue what I'm looking for. It was almost as if someone had taken hold of my hand because I found myself reaching inside the tray/box without realizing it.
Me: "Which one?" - as my hand is almost guided to a particular spot in the box.
SSV: "That one..."
Me: "This one here?"
SSV: "No, the one just to the left of your hand"
Me: "That one?"
I located the proper chuck, and after verifying the tap was about the same diameter as the bolt shaft and had the same t.p.i. (like I would know!), I set it into the crankshaft.
I think back now of ALL the ways this could have gone wrong for me...sheesh!
The tap went straight in.
I began to turn the chuck...one...two...three turns...
And the SSV says very abruptly "stop!". I stopped. "Now, chase it with the bolt". I removed the tap, and a 2cm piece of damaged thread, from the hole; and held my breath as I threaded the bolt into the crankshaft.
It went in straight! I socked it up almost to full length, but was advised "that's far enough", and removed the bolt again. One or two threads on the bolt end were a little shiny, but not enough damage to render the bolt un-usable. Put the other crankarm back on, tightened both, Job Complete...
Now, the point of the Q&A at the beginning of this entry...
By the time I finished Lionel's bike, it was almost 10:30; but I still had one MORE job to do...while the tools et al were still out on the bench.
My commute time has been steadily growing over the past two months, especially since I rode the bike in the rain. My bottom bracket was sticking - badly. Got it popped apart and sure enough, one whole set of bearings had fallen apart and several parts of the crankshaft were REAL shiny on that side as they had been scraped clean by bits of crushed bearing and broken bearing race. I had a couple of new wrecks in the shop, and a suitable replacement crankshaft was among the parts I got off those wrecks. Suitable, yes...but shorter.
After assembling and re-packing the BB on my bike, I realised that shorter crankshaft is a better fit. The longer length one allowed me to put a little too much torque on the cranks and chainrings...which is why they're almost falling apart right now...sigh. The extra torque was also probably helpful in destroying the previous set of bearings.
So: rode yesterday and today. Trip time is back down to 45 mins. Yes!
Only now I noticed the front wheel is starting to grind a little...and the tires need to be swapped.
Sigh...maybe I should take this Saturday off...