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Removing Old OnePieceCranks (IMPOSSIBLE)
#1
I have recently salvaged two very old finnish bikes and the plan is to strip them of all parts, remove the paint and rebuild with some new parts.

I have been able to remove all parts except the OPC (One Piece Cranks) as the lock ring is badly designed and needs some special tool to be removed.

I have attached two pictures of the lock ring that needs to be removed:

[attachment=1113]

[attachment=1114]

There are two holes opposite each other (only one can be seen in the picture).

Any advice on how to unscrew this lock ring would be greatly appreciated, because i need to remove the cranks before i strip the paint off the frame.

Thanks!
//Andy
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#2
I think you need a pin spanner, see here: http://www.parktool.com/repair/readhowto.asp?id=92
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#3
Ah that"s easy to remove all you need is a good hammer and a punch.It does not matter if you mess this old part up they are cheap to buy.You can buy them at any LBS or online store.Sure you could buy a special tool buy for that kind of crank I would not.When you replace it the one you get will be different anyway.Here is a place you can get them at.Amazon.com Don't worry about if it says it for a bmx all OPC use the same well most will anyway.The one you need to take off can use one for a bmx bicycle.After you have work on a few bicycle it will all come together for you.It would be best if you just go to your LBS and get the bottom bracket kit it will cost about 8 bucks.Good luck to you if you need anymore help let us know.Have a great day/night.
My dad always told me a Sledge a matic can fix any thing.
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#4
Turn CLOCKWISE not Counterclockwise, the threads in those are backward threaded. Left to tightened right to loosen. Wink Noticed the marks that you were turn to the left. Looks like a vintage you have there, wish ya good luck and please post the done pics here ... http://forums.bikeride.com/forum-36.html
Good maintenance to your Bike, can make it like the wheels are, true and smooth!
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#5
Thanks for the help!

I tried using a hammer and punch, but the end of the punch was too thick. I might have to go my local hardware store to see if i find a punch with a thinner end.

Yeah, initially i did try to open it counterclockwise but then i looked at the threads...
so now i'm at least trying to turn it the right way =)

The main problem is that it is really tight, i.e. stuck, which makes the whole thing that much more of a challenge heh
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#6
Your welcome, just be careful with that punch idea. Asked someone at the hardware or autoparts store if they have a pin spanner. Make the job sooo much easier. But its up to you.
Good maintenance to your Bike, can make it like the wheels are, true and smooth!
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#7
(07-01-2010, 07:28 AM)Bill Wrote:  Your welcome, just becareful with that punch idea. Asked someone at the hardware or autoparts store if they have a pin spanner. Make the job sooo much easier. But its up to you.

I actually tried with a tool very similar to a pin spanner, but the problem was that the spanner was way too short (under 1 foot) so i couldn't get any momentum. It would have to be around a 2-3 foot spanner if i'll be able to open it by hand

Will let you know what happens =)
This would be perfect!

[Image: pin_spanner_wrench.jpg]
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#8
Quote:I actually tried with a tool very similar to a pin spanner, but the problem was that the spanner was way too short (under 1 foot) so i couldn't get any momentum. It would have to be around a 2-3 foot spanner if i'll be able to open it by hand

A peg spanner isn't strong enough for a lot of leverage. They're pretty lousy things and I'm glad peg holes have been dropped from modern components in favour of splines, nuts and sockets, on which you can get a decent purchase.

In any case, use some penetrating oil and let it soak for a while to free it up as much as possible. Then try again with a punch, or an old screwdriver, basically anything you can fit in the holes and try to drift the part around.

Good luck.
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#9
When you come to replace, make sure you get the right size, there are different sizes of opc bb sets.
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#10
Finally got them off! On one of the bikes the lockring came off without using too much force with the punch and hammer, but the other one was a real pain to remove. Here are some pictures of the process:

[attachment=1157]

I was surprised to see that the cups were in fact threaded. Luckily i realized that before using too much force trying to bang them out =)

[attachment=1158]

The older of the bikes was really rusty so getting the lockring off was quite the struggle as can be seen from the lockring (the one on the right was the easy one)

[attachment=1160]

The punch ended up bending when trying to remove the lockring from the second bike, so i had to saw off the bended bit

[attachment=1159]

Now starts the fun, rebuilding the bikes!
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#11
Wow great job. Glad to see you got it off. So it was pretty tough on the second bike huh? What kind of bearings were in it just out of curiosity?
Good maintenance to your Bike, can make it like the wheels are, true and smooth!
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#12
(07-14-2010, 07:18 AM)Bill Wrote:  Wow great job. Glad to see you got it off. So it was pretty tough on the second bike huh? What kind of bearings were in it just out of curiosity?

Pretty tough is an understatement =)

Don't have a photo of the bearings but this is approximately what they look like: [Image: bearings_crank_one_piece.jpg]

To me they look exactly like the ones in BMX One Piece Cranks
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#13
Ahh ok, the older 60's and earlier have loose ball bearings in them. They are a monster to replace. Good that you do have caged.
Good maintenance to your Bike, can make it like the wheels are, true and smooth!
  Reply


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