Removing FAT BB

mkozaczek

New member
So, one of my Yos has a completely dead factory BB.

My idea of how to remove the BB is as follows

1. Remove collars from BB spindle
2. Remove metal clips from BB cups
3. Press out BB spindle (through either side, but I'll press from non-drive side)
4. Pop out the BB cups using something like headset cup removal tool

Am I in the ballpark??

Thanks,

Martin
 

mainlyfats

New member
So, one of my Yos has a completely dead factory BB.

My idea of how to remove the BB is as follows

1. Remove collars from BB spindle
2. Remove metal clips from BB cups
3. Press out BB spindle (through either side, but I'll press from non-drive side)
4. Pop out the BB cups using something like headset cup removal tool

Am I in the ballpark??

Thanks,

Martin

If it's from the factory, then there are no cups, just bearings. As long as they are really truly dead, just use a drift and a hammer and bash them out from the backside.
 

rody

New member
As posted previously on the board (search function is nifty)...

The press in bottom bracket used in the early Fats is not difficult to work with, but takes some understanding.

The bb shell has two internally bored reliefs for the bearings to press into with approximately .004" interference fit. Snap rings on the external diameter of the bearing assure proper insertion depth, as they will sit tightly against the face of the bb shell. The bb spindle is smooth with no shoulders to locate the centerline, instead relying on locking collars that slide over the spindle and pinch to maintain your chosen chainline.

To remove an old set of bearings in the home mechanic setting with minimal tools, you will need a few blocks of wood with padding, a punch with a square head, and a hammer. Remove the spindle locking collars and slide the spindle out of the bb, it may take a gentle tap with a soft head or rubber hammer. Carefully support the frame on it's side on the ground with the blocks of wood and padding supporting the frame tubing. With the spindle out, insert the punch through the top bb bearing and place the head against the inside of the opposite bearing on the outer edge. Gently tap the punch, moving around the bearing in opposite areas to push the bearing out. Consider the bearing like a clock face, working at 9, then 3, then 12, then 6 etc.. Don't get discouraged if the bearing does not move quickly, small even taps and a little patience are your friend to prevent damage.

Once the bearing is out, flip the frame and remove the other bearing in a similar manner.

To install a new bearing, clean the frame's bb area well, gently sand the inside of the bb to remove any rust deposits, then lightly coat the inside of the shell with a thin layer of waterproof grease (like Phil green grease). To install the bearing, work one side at a time to prevent "cocking" of the bearing in the shell.

Gently place a bearing in position with the frame's bb located in a vice between two pieces of straight wood. Rotate the jaws closed until they just contact the bearing and the opposite bb shell face, insure the bearing is straight and true to the shell. Then advance the pressure to insert the bearing to the proper depth. Repeat on the opposite side.

The spindle should be cleaned and lightly greased, then inserted back into the bearings. Slide the collars into place and leave loose. Install your cranks. Once your cranks are installed, adjust the centerline of the chain and then lock down the collars. You should be all set.
 

mkozaczek

New member
Thank you Rody. You should post this on your website for posterity.

An order for some bearings will be coming your way, as well as another set of decals.

Also, I got that Grove Frame on eBay. It's with my other one at Bill's right now =)
 
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