geoduck

In my ongoing quest to build my ultra-cheap ss mountain bike, I went to remove the crank (square taper) in order to service or swap the crusty bottom bracket.

I had a hell of a time getting the drive-side crank arm to budge using the Park extractor tool, and by the time I was finished, the extractor threads on the crank arm were stripped (*hangs head in shame*). This thing is on TIGHT.

So what to do to get this crank arm off? I'm not even sure if I want to use it again, because it is a cheapo with non-removable chain rings. I don't really want to build up a single speed with a triple on the front .

The options I've heard so far at two shops:

- re-tap the threads to a slightly larger size, and remove the arm using a special Park tool (larger-size extractor?). Crank arm may be reusable, but probably not easy to get off next time.

- use a propane torch to heat the extractor arm at the spindle interface, wait for metal to expand, and try to knock or pry it off.

- use a Dremel-type tool to cut through the crank arm in two places near the spindle (downright barbaric, IMO).

- try to muscle it off with a mallet, pry bar, etc. This sounds like the least-favorable method, as it could damage the bb or the shell.

Does anybody have experience with any of these methods, or any other ideas?

TIA

_'duck

roadfix

Try riding your bike without the crank bolt. Hopefully the crank will loosen on its own after a few miles.
Your other option is to use an automotive gear puller to pull your crank off.

MudPie

Instead of taking the crank bolt completely off, loosen it and ride the bike around. When the crank arm works itself loose, it won't completely fall off the bottom bracket spindle.

Also, when removing the crank arm, make sure the crank bolt washer (if any) is removed.

cballay

If you want to be really barbaric, cut the BB spindle with a saws-all, since your going to scrap the BB. Then you can put the crank arm in a vice and punch the spindle piece out with a hammer and a large hole-punch (if you really want to keep the cranks). These are 3 tools that are not made by Park.

Poguemahone

Gah. There are tools made for this kind of operation; they're very similar to a pry bar. You place them in between the BB and the crank arm and simply pry the crank arm off... I see no reason why your basic crowbar would not perform the same service. I'd loosen and ride about first, though. Sounds like less of a hassle.

roadfix

You Animal!

24601

Seems to me the automotive type gear puller might be the best idea.

RegularGuy

The gear puller is a good idea if you can get one to fit.

Here's an elegant solution:

https://www.bicycletoolsetc.com/index...&item_id=CV-22

That website also has gear puller-type tools, though they are pricey. They used to sell a bargain basement pry bar for $7.50, but it is no longer available. I wish I'd bought one!

Finally, the barbaric way is effective. You can also do the cutting with a hacksaw. If you aren't planning to use the crank again (and I wouldn't use a stripped and re-threaded crank, but that's just me) it is effective. Go ahead and embrace your inner barbarian.

MudPie

This tool looks just like an automotive ball joint separator. It's more a wedging action that'll separate the crank from bottom bracket. Instead of buying one, borrow one from your friends that do automotive work, or visit a local auto garage and see if they can use one, or you might be able to get a free loaner from a local auto store. It'll probaly take one or two whacks with a hammer to separate. Or you could buy a cheap-o quality one for under $10.

BTW - cutting the bottom bracket spindle may be difficult. Those spindles seem to be made of a hardened steel.

geoduck

Thanks for all the great replies!

I think I'll raid my father-in-law's shop this weekend. He's a former ironworker who has all sorts of pry bars and such.

Yes, I'll probably ride the bike a bit first to loosen that bad boy up. I'll try and post back here next week with the chosen solution and what the outcome is.

_'duck

Silverexpress

Just curious to know if you got that crank off, and what method youu used. I've got the same problem....doh

DannoXYZ 

I've used a crowbar stuck in between the cup and crankarm to pry it off before. Have also used motorcycle tyre-irons. Used the automotive gear-puller a couple times. One time I took the entire assembly off by unscrewing the fixed up. Laid it over the jaws of a vice so that the spindle slides through easily, but the cup rests on top. Loosen the bolt about 1/2 way, set a 6" socket extension on it, and smacked with a 10lb mallet.

askrom

On a recent occasion where I had the same problem, I tried everything described above except the re-tapping and none of them worked.

dmarcoul

im going to try the blow torch method tomorrow and will let y'all know how it works.

jur

I once tried a gear puller. I just bent its bolts. Went to LBS and bought a proper crank puller. It was easy once I got the right tool. The gear puller I used was a lot less effective, perhaps the size was not right for the job.

top506

Before I broke down and bought a crank puller I used the 'ride it 'til it loosens up' method. Never took more than a 1/4 mile.
Top

Phantoj

I'm not sure it would work here, but I used to remove dirt bike flywheels (tapered fit) with the following method:

1. Have an accomplice pry on the part to be removed (crank arm in this case).

2. Use a hammer and a punch to tap on the spindle.

Keep tapping and eventually the part comes off.

Coda1

I stripped the threads out of a set of cranks a few years ago and got one side off by riding it with the bolt loose but the other side wouldn't come off that way. I used a sawzall to cut a slot in the crank almost to the spindle and it popped right off.