Phil_gretz

I'll need your collective wisdom on this. 1999 Trek 520, Shimano triple with stripped drive side crank threads. Maybe someone forced the steel dust caps, I don't know. I'm afraid to force thread the standard crank puller, because of the risk of cross threading and the weakened threads. The loose ball BB is a muddy, rusty mess. and I can't imagine simply re-packing it, especially since I can't get to the drive side.

So, what are my options? This is a friend's bike, and I want to salvage the crank. I'm thinking that a cartridge bearing is the best longer-term bet. But to install it, I need to get the drive side off.

There are automotive jaw pullers made for gears and flywheels. Do any of you have experience using one of these for cranksets? I'll have to buy the puller to help my friend. Maybe the harbor freight models? If you can guide me, I'd really appreciate it.

Phil

shelbyfv

I think chuck wedges are the preferred method. I've also read that you can loosen the crank bolt and carefully ride around until the crank comes free. Never tried it.

AeroGut

I've done it (carefully) with a pry bar. Put the bent end of the pry bar right by the spindle pushing against the cup/BB shell, with the bend angling towards the bike. Then lever against each arm of the spider, working your way around the circle until it comes free. Might scratch up the cup a bit.

Eggman84

If the DS crankarm is stripped, why would you want to reinstall it. Someone else would then be presented with the same problem in the future. I guess you could try to re-thread the crank (or install a heli-coil - can that be done on Al alloy?) when the crankarm is off the bike. Good luck.

ramzilla

Get a cheap crank arm removal tool that can be sacrificed. Place bike on side and fill the crank arm mounting hole with something like WD40. Take the drive pin completely out of the removal tool. Get a 14" adjustable wrench and use brute force to insert removal tool body as far as it will go in crank arm hole. Then insert the drive pin and get that crank arm off. OK, Anyhow right. If all else fails you can always fire up the sawzall or a high speed grinder and just destroy the whole mess and start over.

WizardOfBoz

Chuck wedges will apply enormous force in a controlled manner. Shim up with washers cut in half and tap inward with two hammers.

https://www.amazon.com/Apex-Tool-Gro...SIN=B0006571JM

Andrew R Stewart 

https://www.steintool.com/portfolio-...ractor-system/

I have yet to use this tool but have a number of Stein tools and they are all very effective. If I still ran my shop I would have this in my tool chest. Perhaps a shop in the area has one and can do the job? Andy

Trevtassie

Nice bit of gear! I'm a fan of good self extracting crank bolts anyway.

Phil_gretz

Karl, This is a good question. In brief, my friend really loves his bike (I'm now guessing an earlier 90s or late 80s, not 1999.) He was refused by a bike shop when his Uniglide cassette was severely worn. They said, "buy a new bike. you can't get parts for this anymore." He brought it to me (this was 7 years ago?) and I was able to pull the later gen Uniglide freehub (bolt on, not press fit) and replace it with Hyperglide. New chainrings and chain, and we got him rolling again.

He'll never pass this bike to anyone else, but will ride it as long as he can (he's in his mid 60s now). So, I'm figuring that a cartridge bottom bracket will be the way to go now. I may try to re-thread drive side crank as Andy suggested. I need to call around to the shops who know what they're doing and see if the tool exists here. Most larger chain-type bike stores don't really know much other than "remove and replace".

Thanks, Andy. This would be the best approach. Once I get this thing off. I'm thinking that the wedges are the way to go.

Phil_gretz

Thank you for the inputs so far. Has anyone tried one of these pullers on this type of problem? Maybe the smallest one?

AeroGut

If you don’t want to buy a new tool, another option you have in this case is to remove the cup while the crank is still attached and take the whole mess off the bike. Once off the bike, the spindle can be punched out of the crank relatively easily.
But if you can get ahold of wedges or other proper tools, that’s of course the much better way to go.

Trevtassie

I think the idea of that tool is that you use the supplied puller in the new thread... so you don't need wedges.

andrewclaus

The gear pullers will not work. The chain rings are way too flimsy.

I use an automotive ball joint separator, what my shop mentor called a pickle fork. I have one in my auto tools anyway. It's a well-used tool at the bike coop where I volunteer. It'll put a couple of marks on the fixed cup, and in tough cases maybe on the shell, but it works. Use eye protection when banging on it, as always.

Using this tool will probably make you get a new crank, but that's sort of the idea.

RoCou

You need to pull on the crank spider, not the chainrings. It works - if you have the right puller that will fit into the crankarm hole, sit correctly on the axle face, and grab correctly onto the spider. Not obvious that all 3 conditions will be met. If I had to do this job, without new tools, I'd use Aerogut's method - take out the drive side cup (a challenge by itself in many cases), pull out the crankarm with the axle, and then punch the axle out.

Stripping the extrator threads was a common issue with square taper crank axles. No wonder someone invented a re-threading kit complete with oversize extractor and oversized dust caps.

JohnDThompson 

I'm not aware of a helicoil repair for stripped extractor threads, but VAR does make a kit to cut oversize threads into a stripped arm, and an oversize extractor tool for use with the new threads. The kit is not cheap, but perhaps a local shop may have one already.



N.B. it's possible that rethreading the arm and purchasing the oversize extractor may cost close to what a new arm with intact threads would cost.

Moe Zhoost

I have a set of Jacobs Chuck wedges that work great to pull anything held on to a shaft by friction. I've not tried them for bike cranks; however they would be the first thing I grab if I encountered a stripped crank arm. An alternative is to use two opposed pickle forks (AKA ball joint separators). Opposing them keeps the pressure parallel to the both the fixed cup and crank.

WizardOfBoz

Phil, I have gear pullers. I'd use chuck wedges - more control, easier to get into the space between the cup and the arm. The gear puller, even if you hook it onto the spider, is going to be hard to get into that space. Plus, most gear pullers have two or three arms. Your crank has 5. That's going to make it difficult to use a hub puller.

There's a cost issue here, too. The VAR kit costs about $130 plus shipping. A good hub puller is going to be from 60 to 200 bucks (cheaper ones can be found, but they are just that... cheaper).

2cam16

If all else fails, like it did with me with one of my bikes, cut it off with a Dremmel type of tool.

HillRider

This is the real problem with a gear puller. The spacing of the gear puller's hooks and the crank spider don't match and getting a good grip without damaging the spider is difficult.

For $10 the chuck wedges linked to above are definitely the way to go.

WizardOfBoz

So, to pile on, keep in mind that chuck wedges were designed to allow one to swap drill-press chucks. These chucks use tapered joints - like cranks (round tapers vs square, but tapered just the same).
So the wedges were specifically designed to break tapered joints.

BTW, make sure you get the right size of wedges, if you get chuck wedges. I'm guessing you want JT3 (Jacob's drill press Taper 3), for which the large size of the taper is 0.8110". But you may want the JT6 (which is smaller, go figure). Here's a chart for all of the four different wedge sizes:

JT1 0.3840"
JT2 0.5590
JT6 0.6760
JT3 0.8110

Phil_gretz

Thanks, you guys. I'm going with wedges for now. I'll update once I have this thing fixed and working right again. Phil

Crankycrank

Why not at least try to get the puller screwed on. The threads are already partially damaged so you've got nothing to lose. Just make sure you've got the puller screwed all the way in and pour some hot water over the crank to aid in getting it off.

Eggman84

Seems you have plenty of recommendations how to remove the crankset. I understand wanting to keep the bike period correct; I have a Trek 520 from 1992 that is essentially unchanged though I have replaced the original Shimano 7 speed freehub/cog/bar-end shifter to 9 speed components. To that end, if the crankset is damaged you could replace it with one from e-bay (lots are available). I would recommend the Shimano FC-MT60 (old deer head level) or FC-M730 (slightly newer XT level). Both cranksets are 110/74 BCD; what they used in that era.

Good luck.

RoCou

In a bike repair thread, the probability of a Dremel being recommended increases exponentially with the length of the thread.

(I'm guilty of dremeling threads here as well).

Phil_gretz

This wound up (indirectly) being how I saved and re-used this crank for my friend. I was unable to pry the crank off with wedges or pickle fork, but I did use the wedges to keep a headset wrench firmly in place on the fixed cup. I backed it out and took the crank/spindle/fixed cup over to my bench vise. Clamping the crank in the vise, I carefully threaded the removal tool into the remaining threads, got a long lever and torqued it down into the bottom, inner threads that had been virtually unused. Maybe three full turns of extra threads.

I held my breath and began driving the inner part of the tool against the spindle. Voila, the spindle moved and dropped out. Yay!

A Shimano cartridge bearing and new chain later and my friend's 520 is on the road again. Of note, the original(?) spindle was a shiny steel Shimano 70-122.5mm. The bottom bracket shell is a 68. Wouldn't this have placed the "shoulders" for the bearings 1mm wider than intended by Trek on each side? Thanks for the inputs, all. Phil