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-   -   help installing 3 piece cranks (http://www.bikeforums.net/bmx/123558-help-installing-3-piece-cranks.html)

goaliej01 07-20-05 05:53 PM

help installing 3 piece cranks
 
i need help dissassembling my one piece crank and putting in my new one.

i took apart everything on my one piece, and i have 2 fittings stuck in my bb that i cant seem to pop out.
any help?

Flatline 07-20-05 06:03 PM

The two fittings are called cups. They are what your ball bearings ride on. Hit them out with a hammer and a screwdriver.

kwhord 07-20-05 06:27 PM

tools needed for crank replacement:

1. Hacksaw
2. Blow Torch
3. Hammer
4. Vice Grips

Remove existing cranks w/ conbination of hammer / blow torch / hacksaw.
Install new cranks: apply combinations of Hammer / Vise Grips as needed.

CMcMahon 07-20-05 06:59 PM

You forgot the belt sander.

bmxrdr88 07-20-05 07:13 PM

Don't forget the pipe cutters!

kwhord 07-20-05 07:30 PM

crap, thanks guys. he would have a really hard time without the pipe cutters!

hypersnazz 07-20-05 10:47 PM

Supplies needed:
2x4
hammer
gigantic flathead screwdriver

1. Remove your old BB by pounding it out with hammer and screwdriver. Throw it away, because whatever shape it was in when you started, it's detroyed now.

2. Set one cup into the shell, placing the 2x4 over it and bang on it until it's smashed in there nice and crooked. Reapeat on the other side. Do not grease the BB shell as it will probably just make a mess.

3. Repeat with the bearings. Ideally your bearings should be wedged in crooked. Assuming the mangled cups are also crooked (see step 2), equally crooked bearings will cancel this effect out, as long as they're tiled the other way (and equally mangled). Again, avoid grease.

4. Insert spindle and reattach arms, torquing bolts to exactly 2138748132908734738126 in-lbs each.

5. Suddenly remember that you forgot to install spacers.

6. Remove arms, install spacers and reattach arms. A cheater bar may be required to properly torque crank arm bolts for those at significant risk of heart attack or aneurysm. A length of pipe no less than 13 feet long is recommended.

7. Complain on the internet about stiff bearings, creaky BB and wobbly crank arms. Blame it on the manufacturer and vow never to buy their products again.

cru jones 2 07-21-05 12:06 AM

to get the cups out don't use a screwdriver as posted above. if you have an old bike axle if you have one lying around or something of that nature. i've also used old socket extentions that i had no intentions of using again for wrenching. when in doubt obtain a B.F.H. (big freakin hammer). make sure you rotate around the cups and don't just bang them out using one spot, don't want to chance mushrooming out your bottem bracket shell.

Brian 07-21-05 01:19 AM

I love my headset/BB press.

hypersnazz 07-21-05 01:54 PM

Quote:

Originally Posted by Expatriate
I love my headset/BB press.

SHHHH! Don't talk such things on a BMX forum! I bet you've got grease, shell reams AND cutting oil too. Heretic.

goaliej01, if you haven't gotten the vibe by now, headsets and press-fit bottom brackets are two things you should NOT be working on without the proper tools. It's so much cheaper to pay a bike shop 10 bucks to press the cups in than it is to f*ck up your brand new set.

kwhord 07-21-05 02:18 PM

really all you need to set cups on a bmx bike is a home-made cup press. just a long, beefy bolt w/ washers on either end large enough to catch the cups. crank the nut down with a box wrench until the cups are properly set. you can pick up these parts in a hardware store for ~ $5 vs paying a bike shop to press the cups for you. If all else fails, just use a hammer and a blow torch.

Brian 07-21-05 02:40 PM

Hammer and blowtorch? Please! A bottle jack and a suitably low car are all you need - that will give you 3000 pounds of force to press them in.

hypersnazz 07-21-05 02:42 PM

Quote:

Originally Posted by kwhord
really all you need to set cups on a bmx bike is a home-made cup press. just a long, beefy bolt w/ washers on either end large enough to catch the cups. crank the nut down with a box wrench until the cups are properly set. you can pick up these parts in a hardware store for ~ $5 vs paying a bike shop to press the cups for you. If all else fails, just use a hammer and a blow torch.

5 bucks doesn't include facing and greasing the shell, and a ream isn't exactly something you can DIY at the hardware store. Some might say it's unnecessary (especially on a BMX bike) but I like my stuff to last, and I've yet to have someone ride my bikes and NOT say they're the smoothest, tightest, quietest bikes they've ridden.


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