Michael_P

Hello all,
first post to the forum so apologies if I have posted this in the wrong place.

So I picked up a free frame at the weekend as it was begging to be saved. Can't quiet make out the make but hopefully a clean will revel its origin!

As you can see in the photo the sprocket is bent over at 90 degrees and I was going to replace it today but that's where I hit a snag. See the photo below.

So I was expecting the dust cap to have an external thread but instead it has an internal thread. That means that no extraction tool I own fits it.
I spent some time flicking through Google but couldn't find a match to this type of crank retention.

Any assistance identifying it and how to get the crank of is much appreciated!

Thank you,
Michael Powell

Hold tight as I can't seem to post photos. I will try and get a link to one of the crank!
​​​​

Bob the Mech

You need 10 post to post pictures...limited to 5 per day as a newbie...you can't post links yet either

daverup 

OP gallery,
https://www.bikeforums.net/g/album/18858042

Michael_P

Ah right, that makes sense.
good call on the gallery there, didn't know that was a thing either.
Scrubbed the front name plate of the frame and it says "Schuhoff". No idea if that helps!

Cheers guys,
Michael

WGB 

Michael_P

You might try The Cabe.
The Cabe is another cycling website but it deals mostly with weird old bikes. I suspect your bike is German and very old and obscure and someone there might know it. Also IIRC You can post photos immediately after joining.

T-Mar

When I come across older cotterless cranksets without extractor tool threads (or ones with stripped threads) my first resort is a small automotive gear puller.

Michael_P

I will drop a post on the Cabe, might find something interesting out about the frame

I actually did try a gear puller, but I started to bend the sprocket rather than pop the crank off. Might need to soak it in oil, it probably hasn't come off since it was made!
If all else fails then I have an angle grinder...

Thank you everyone for the help!

madpogue 

It LOOKS like there's a spring washer deep in there, one of those with internal tangs that engage the threads on the stud. I forget the exact term for that kind of washer. But I'm making out dark spots pointing inward toward the stud at regular intervals, which suggests one of those kind of washers.

Do you have any of those drill chuck removal wedges?

Michael_P

I can see what you mean but I think it's a trick of the light.
i have uploaded another picture to my gallery to try and get a decent image of inside the crank. Not the easiest to show.
In the pictures the dark triangles are the gaps between the square crank and slightly less square shaft.
​​​​​

madpogue 

Yes, I see the four dark triangles at the corners of the square taper. But look along the top part of the opening in the new pic. You see those two rust brown bits between the corners? If you have a pick with a 90-degree hook, get in there and pick at those points; it just look like there's "something" there.

Bob the Mech

Schürhoff badged, German bicycle, motorcycle and toy sewing machines makers...beyond that I've no idea.

old's'cool

A machine shop in addition to cycle works, offering automatically produced turnings according to pattern or drawing, up to 48mm diameter.

bulgie 

Heat is a big help when removing cranksets. Heat makes things grow (thermal expansion). A heat gun can often be enough, but a propane torch is faster. Faster is better because you can often pop the crank off while the crank is hot (and expanded) but before the heat has conducted in to the spindle. You want the crank to expand more than the spindle, to loosen the press-fit.

Good luck
Mark B in Seattle

canopus 

Another option is, IF you are not into saving the BB spindle, just cut off the spindle behind the crank arms. Then you can press the bits out of the arms later and remove the BB from the frame. A hacksaw or die grinder with a cutting plate should do.

Michael_P

Evening,

I appreciate everyone's help, over on Cabe I was told it's a Glockenlager type crank.
apparently very difficult to remove.

So at the weekend I will use a cold punch and blowtorch to persuade the cranks off.

Cheers all for the help, I really appreciate the time

Michael

dddd

I'm thinking that a pickle-fork style tie-rod end/ball-joint separator tool may have been the intended service tool for arm removal.

Have you allowed a good penetrant to work on that over night?

Michael_P

I think I know the tool you mean. Might dig around in the tool box see if I have something similar.
i haven't soaked the cranks yet. I have tallied it up as a weekend job!

madpogue 

^^^^^^^ Drill chuck wedge works similarly to a pickle fork.

Time is your friend when it comes to penetrants. May as well start soaking it now.

Michael_P

Thank you all for the assistance, I can confirm I have got the cranks off. Took a cold chisel, a lump hammer and some hefty hitting. It really out up a fight!
But it's off. Going to stick a cottered crank on since I have it laying about.

Thanks everyone