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Crown race moves - fork diameter too small.

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Crown race moves - fork diameter too small.

Old 09-18-19, 05:20 PM
  #1  
greysquirrel
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Crown race moves - fork diameter too small.

I bought a new fork with an Al steer. When I put my old crown race(1 1/8 thread less) on it, the race is totally loose and actually wiggles slightly. I tried other crown races and measured the fork with calipers. Seems like the steer is slightly smaller than spec. Is there any way too use the fork safely? (BTW The dealer was out of replacements, so they gave me a refund and told me to keep it.)
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Old 09-18-19, 05:33 PM
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You could probably have a machinist knurl the steerer to increase its effective OD but I am unsure of the long-term consequences of doing this.
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Old 09-18-19, 06:22 PM
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.
...because it's an aluminum steerer, I would be inclined to try one of the bearing bedding compounds from Loktite. Assuming it's only slightly loose, centering should work out OK, and you shouldn't need to worry much about the gap. You'll never be able to get the race off again without some difficulty, but it ought to work for quite a while...they use the stuff to seat crankshaft bearings in engine rebuilds.
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Old 09-18-19, 06:36 PM
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A thin brass shim will wedge into the space and fill it so the race does not move. Find a place where you can get a small piece of the brass (it won't be cheap) like Micheal's or Hobby Lobby. Then cut it to the right diameter/circumference of the steering tube and place it on the tube so it rests on the race holding ledge at the point of contact with the crown of the fork. Then using s race setting tool, drive the race in place. The brass will mold to the correct position to hold the race centered on the fork. HTH Smiles, MH
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Old 09-18-19, 07:34 PM
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Originally Posted by Mad Honk View Post
A thin brass shim will wedge into the space and fill it so the race does not move. Find a place where you can get a small piece of the brass (it won't be cheap) like Micheal's or Hobby Lobby. Then cut it to the right diameter/circumference of the steering tube and place it on the tube so it rests on the race holding ledge at the point of contact with the crown of the fork. Then using s race setting tool, drive the race in place. The brass will mold to the correct position to hold the race centered on the fork. HTH Smiles, MH
I am skeptical that such a shim will stay in place while the race is driven over it (I believe that it will buckle) but if you want to try it many hardware stores such as Ace Hardware have a K&S Metals display which has various thicknesses of brass shim stock, or McMaster-Carr has a very comprehensive selection. A local machine shop may also be a possible source.
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Old 09-18-19, 07:48 PM
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It won't buckle if the shim is tall enough to extend beyond the ledge from the original race cutting when it is driven on. That is the reason why it needs to be placed against the bottom of the steerer and the crown before the race is driven into place. The amount of material needed to fill the void can be problematic, but careful measurement of the thickness needed will aid in the procedure. It is in no way different than brazing around the tube to make it fit. Smiles, MH
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Old 09-18-19, 09:53 PM
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If you are going to try the shim method try using a soda or beer can.
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Old 09-19-19, 07:07 AM
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Shim stock which is available in 0.0005 increments is used to get as perfect a fit as possible which is what I would want if I were inclined to try shimming, but I think 3alarmer has the safer approach. That said I would not use the fork, a sudden change in the headset/steerer connection at the wrong time, like a high speed cornering or decline could leave you with serious instability. I suppose if you just lazy ride around the neighborhood you might be fine but you are not out anything, get a good fork.
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Old 09-19-19, 09:02 AM
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Contact the company that makes the headset. Some carry undersized race spares. I believe Chris King still does so if no luck check to see if the King race has the same bearing angles.
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Old 09-19-19, 10:11 AM
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As mentioned, Aluminum can. Cheap, easy, effective. If it eventually develops play again, no harm no foul.
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Old 09-19-19, 02:17 PM
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Originally Posted by Crankycrank View Post
Contact the company that makes the headset. Some carry undersized race spares. I believe Chris King still does so if no luck check to see if the King race has the same bearing angles.
It's a 15 year old Cane Creek headset. I'd think I'd be lucky to even get replacement parts.
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Old 09-19-19, 02:20 PM
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Originally Posted by frankenmike View Post
As mentioned, Aluminum can. Cheap, easy, effective. If it eventually develops play again, no harm no foul.
My concern is my head tube being damaged.
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Old 09-19-19, 02:45 PM
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Originally Posted by greysquirrel View Post
My concern is my head tube being damaged.
An aluminum can shim shouldn't contact the head tube. It would fit between the fork's steer tube and the crown race.
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Old 09-19-19, 03:03 PM
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Originally Posted by hokiefyd View Post
An aluminum can shim shouldn't contact the head tube. It would fit between the fork's steer tube and the crown race.
Thanks hokiefyd!
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