Frozen Ultegra 6503 Crank Arm & BB - Ideas?

[Marcy]

I've got a nice older CXII I picked up from a forumite recently, and am stripping it down to protect it with Frame-saver & upgrade parts.

Have hit a snag with the Ultegra 6503 left non-drive side crank arm and bottom bracket. The drive side crank arm came off the BB OK, but the left arm is really stuck. It's soaking in Liquid-Wrench penetrating oil as I type this.

The threads for the extractor bolt were damaged from the previous owner or his shop, and won't hold the crank arm bolt. I've got the crank arm bolt and extractor out, but have no way to pull the arm off with the crank arm bolt, since the extractor bolt threads are damaged. I tried heating the arm and tapping it sharply from behind, but it won't budge.

Any ideas? I used to work in a shop back in the late 80s, and am a pretty good mechanic. However this bike has many over-torqued parts, and the left crank arm is the worst I've ever run across.

I went to the Shimano tech page thinking maybe I could just pull the BB with the arm attached, but the main part of the BB body comes out from the right side (like most cartridge BBs), so I have to get the left arm off. Oh yeah -- the BB seems to be in way too tight as well, from what I can tell testing the right side (I realize it's reverse threaded).

I suppose I could hack-saw the left arm off by cutting through the spindle-- the crank & BB are pretty much toast anyway. Never had to do anything that drastic before, but I suppose there's a first time for everything. Here is the Shimano tech page for the 6503 Crank & BB:
http://techdocs.shimano.com/media/techdocs/content/cycle/SI/Ultegra/FC6500/SI-16T0B_En_v1_m56577569830611829.pdf

Grrr. Sage words of advice will be enthusiastically received! Thanks in advance for any help you can render...

-- Marc

[regularguy412]

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[regularguy412]

Try putting the crank/spindle in the freezer overnight. Then heat the crank arm and tap. Sometimes the barely perceptible movement from the freeze/thaw process will be enough to break the joint loose. I've successfully used this method with a heavily corroded rear brake cable adjuster barrel that was stuck in the caliper arm.

Good luck!

Mike in AR:beer:

[regularguy412]

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[Marcy]

I've done this before with small parts, but my freezer isn't big enough to get the whole frame in -- the BB is still in the bike.

I'll try heat again though, maybe that'll break the crank arm free.

Thanks!

-- Marc

[Peter P.]

There's a kit available in well equipped bike shops which enables them to remove the damaged threads and install a helicoil insert. Find a shop that has the tool. It's in the VAR Tools catalog.

[thwart]

Not sure you'd want to use the above if the crank is not in good, reusable shape anyway...

I'd call my local LBS (if they're good at what they do---I'm lucky, mine is) and ask their advice. Methinks the hacksaw may wind up being the answer, and then hold out hope for the BB coming out in the conventional way.

[Mike748]

Is there enough clearance between the arm and BB to put a gear puller or tie rod end puller on it? You'll need to put something in the hollow BB axle to push against...

Otherwise, use a dremel or hacksaw to split the crank arm and a cold chisel to pry it open.

[Marcy]

Thanks folks, I'm about to have another go at it.

Didn't know the VAR tool existed -- but saving the arm isn't a priority since the extractor threads are gone.

Splitting the arm -- I like it! Didn't think of that. If a hacksaw on the spindle doesn't work, I may try that.

Then again, maybe the Liquid Wrench has worked its magic, we will see!

Again, appreciate the input...

-- Marc

[Tobias]

The puller suggestion is excellent, I'd try that first if you have one. If not, I'd try pulling and pushing on the top of the crank arm (at pedal end) in direction of the spindle axle to bend it back and forth about the BBKT. The crank-to-spindle connection is not as strong in that direction and if I was going to apply force, that would be the direction I'd try most. Holding the frame by the downtube with the crank arm right across from it should make it easy to pull and push perpendicular to the crank arm.

If that failed, I'd try cutting the spindle with a hacksaw next.

[tmessenger]

I just had to do one myself on the drive side I didn't care about saving the arm but I wanted the BB. I drilled 1/8" holes in it perpendicular to the BB spindle then gave it a whack with a cold chisel to spread it, came right off.

tm

[Peter P.]

Just thought of one last alternative-ride the bike with the crankarm fixing bolt very loose (try securing it with loctite). Sooner or later it will work its way free on its own.

[R2D2]

I've done this before with small parts, but my freezer isn't big enough to get the whole frame in -- the BB is still in the bike.

I'll try heat again though, maybe that'll break the crank arm free.

Thanks!

-- Marc

Pack it in dry ice.
Freeze and thaw a few cycles.
If that doesn't work and you don't care about crank arm, then time for the Dremmel.
Cut a slice down to spindle and use wedge to open up.
Or cut the other half too.

[dwightskin]

1) Use a parktool crank puller, part number CCP-4C, this might be able to pick up more threads than the self-pulling bolt

2) Use a "gear puller". Google gear puller and you'll see what it is. Automotive shops would have it.

3) Dremel through the crank-arm. It's aluminum and should cut fairly easily.

4) Hacksaw through bottom bracket. This sounds hard - the bottom bracket is hardened, i think.


Let us know how it turns out.

[Marcy]

OK, I tried the Park tool (should have mentioned that in the first post) -- no joy, the extractor threads are toast.

Yes, I have discovered spindles are made of hardened steel -- a hacksaw after 10 minutes barely left a mark, so that's not going to work. I now have a new respect for spindle strength!

I think the drill or dremel through the crank arm is going to be my next attempt.

And as I mentioned before, the BB also really seams to be absurdly tight. Shop or owner that put this together did not beleive in torque wrenches! Any ideas how to get this thing off are also appreciated.

Some great ideas, thanks for the brainstorming. I want to get this BB/crank assembly apart without damaging the frame, and appeciate all your thoughts. :)

-- Marc

[RPS]

I think the drill or dremel through the crank arm is going to be my next attempt.
Since I have little patience for stuff like this, I probably would have already used my angle grinder to remove the crank arm; especially since you are discarding it anyway. With aluminum being as soft as it is, I expect I could grind down to the spindle (or close enough) in a matter of seconds. Even a good file should go through it fast.

If the BBKT is that tight, there are two things I would do. First I’d secure the tool with a bolt through the hollow BBKT spindle to make sure it will not jump out of engagement when torque is applied. Secondly I’d use a long cheater bar (or tube) to apply torque with a long lever arm so as to allow me to hold the frame (to counter reaction forces) at the head tube or top of the seat tube. If you have to apply that much torque to the BBKT shell it’s best the loads be distributed as evenly as possible between the down tube, seat tube, and chain stays.

Hopefully the threads were not secured with Loctite Red or something similar.

[Marcy]

Hadn't thought of securing the BB tool as you mentioned, that is a great idea! I'll have to track down a nice long bolt at the hardware store...

I'll also distribute the loads evenly on the frame, as suggested.

-- Marc

[Mike748]

I use a quick release wheel skewer (front I think) to hold the BB tool in tight engagement while breaking it loose. As it starts to unscrew, loosen the quick release slightly to give it room.

[fjaws]

Or if you work on bikes a lot invest in one of these: http://www.spadout.com/p/shimano-tacx-octalink-bottom-bracket-tool/

TACX makes them for just about every set-up and they work great. They have a bolt inside that threads into the spindle to hold the tool tight.

[Marcy]

Mike 748 -- the QR idea is good.

FJCWS -- But this TACX thing you suggest looks bomber! I've never seen this tool, and for ~$30 it just might be the ticket!

Now if I understand correctly, it screws into the threads that hold the crank arm on so the tool can't slip off the BB engagement ring? Oh yeah, I like this tool...

Thanks! I'll let you know how it works with this very tight BB...

-- Marc

[Mike748]

I agree, that Tacx tool is cool. Clever Dutchmen!