Square taper crankarm's thread is stripped, what now?
 

We have a Santana tandem in for a tune. While installing new chains we discovered that the eccentric front bottom bracket would need adjusting. We have to remove both crank arms since both sides of the bottom bracket have to be adjusted equally. That is when we found that the captain's drive-side crank arm is stripped so a normal crank-puller tool won't work. We tried to get a gear puller from Harbor freight in there but the arms are thick and don't hook the back of the arm very solidly. We have to be careful so as not to damage this original, 30-year-old bottom bracket.

We also tried a torch thinking the arm might heat up more than the spindle...to no avail.

Any suggestions for getting this arm off using other methods/tools? Your creativity will be appreciated.

1. A split plate type puller, assuming you can fit it in.
2. I’m assuming you want a non destructive method, but cutting a split in the crank arm will get it off.
3. Supporting the bike with the BB spindle resting on something to protect the bearings, you can gradually tap the arm off. This doesn’t really work well with non drive side arms.
4. Assuming you can get the other side off and remove the crank and BB from the frame, if you know someone with an arbor press they may be able to press it out.
5. Once upon a time I saw a kit for tapping a slightly larger thread in the dust cover location for just this issue, not sure how common those are.
6. If you only want to save the arm and not the spindle, you can always grind the spindle out. However this might cost you more time and grinder bits than the part is worth.

Say you do get it off, are you planning to put it back on again and repeat next time, or are you planning to replace the stripped part?

Quick. Easy, and gentle on components.

Jacobs chuck wedges, #6.

Fill the space with cone wrenches to get within the working range.

Gear puller will work but (1) you have to put something in/on the BB spindle to push against - a partially inserted crank bolt sticking out proud of the crank arm will work, and (2) you may need some additional plan for holding the 'fingers' of the puller on the back of the arm - a large pair of vise grips or a clamp or a friend holding a pair of channel lock pliers, just to keep the fingers from slipping off the back of the arm.

Something is not making sense, you should be able to adjust the chain tension with the cranks on.

2x on the wedges for the removal. I've also used the pickle fork method.

Pickle fork. $13 at the O’Reilly’s near me. Put it between the frame and the crank arm and whack the end of the fork with a hammer. Should pop off without much effort.

Your link is very bad. You should check it.

I assume you work in a shop. It might be worth your while to invest in something like this. https://steintool.com/portfolio-item...ractor-system/
Not worth it for a one time use but mine has been worth it over the years

I'm guessing you're getting a security warning from your browser. I've seen that numerous times here that turned out to be false alarms.

The BF software defaults all links to HTTPS - even if the original link posted is non-secure HTTP. My guess is that the original link was nonsecure HTTP and that the site in question doesn't do HTTPS properly (or at all). Even today, some sites don't support HTTPS for all links.

The nonsecure version of the link worked for me. Simply delete the "s" from the leading "https:" in your browser's URL window, then refresh/reload the page. (Depending on your browser's settings, you may have to enable nonsecure HTTP also).

SSL certificate is expired:
Issued On Sunday, August 12, 2018 at 7:00:00 PM
Expires On Tuesday, August 13, 2019 at 7:00:00 AM

Not only the security warning but the page I navigated away from was replaced with a website in an east Asian language that was a devil to get rid of.

...I bought one, too, and I don't have a shop. It's been well worth the initial investment to me over a period of 8 years or so.
I originally bought it when I was working Saturdays at the bike co-op here. I was seeing more and more stripped crank arms from people who didn't understand how to pull one without damaging it.

I have some of those Jacobs chuck wedges, and while they usually work, the Stein tool is just easier to use and allows you to effect a repair to the stripped threads, via an insert.

We are replacing the crankarm, want to save the spindle and BB. I think we are going to go through a couple of dremel wheels tomorrow.

If you don’t want to spend the money for a pickle fork, you might look into loaner tools at Autozone. They have pickle forks you can borrow. Put the bike on your car and you can probably knock off the crank in the parking lot.

...once more, unless you are somehow pressed for time, with the oversized crank puller from Stein and the repair inserts they sell with it as a kit, you can repair that crank arm....no cutting, no grinding, no pounding. Piloted tap so it goes in straight. Repair insert restores the original threading. The whole kit costs $120.

That won’t be too bad. Stop a bit shy of the spindle and use something to split the very last part.

If you don't intend to reuse the crank, Unior makes a puller (#1662/4) that cuts new threads. The advantage over the Stein tool is that it's considerably cheaper. I find it takes less effort than a picklefork and it's more portable.

For a bike shop, the Stein is the no-brainer. Cost--at $120--should be a non-issue.

The easiest thing to do is remove the bolt and ride the bike. The crank arm will probably loosen up pretty quickly, but you never know as it might be corroded/frozen in place. Works every time.

Pretty slick system, and saves purchase of new crank set. $120 for tool and two extractors doesn't seem to costly. Good to know it exists and within budget striking distance, if I ever need. Better yet, I'll convince my tool-junkie friend to buy, and I'll just borrow as required.

There is that. Perhaps don’t remove the bolt completely so that the crank doesn’t fall off, however.

Counter experience, couldn't get the DS SqTr crank off my bent about 12 yrs ago and dropped the project for a time, then finished the rebuild but forgot
the crank fixing bolt. Rode bike ~8-9 miles before it finally broke loose, had to one leg it 3-4 miles back to the car, using my R foot to hold the crank on.
So yes it works, but may take longer than expected or a good high torque hill climb to break loose.

That tool looks great. Thanks for the tip.

I was giving the benefit of the doubt to the OP that they would realize the need to carry the bolt with them for when the crank arm loosened.