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Old 12-01-10, 10:24 PM   #1
ultraman6970
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Anybody have seen this before?? 26.4 Crown race lose??

Hi guys...

Have an old frame made maybe 20 years ago and that i took appart maybe like 6 years ago, dont ask me where is the original headset ok? misplaced it and have no idea where it could be so i bought a new threaded 1 inch headset... the crown race its suppose to be 26,4 but now the darn crownrace is lose, I havent finishing painting the fork but either way the crownrace should not be lose. Addind the paint for sure will shim it but thats not the idea i guess, right?

I measured the crownrace and looks like the right size, measured the fork and it is a tiny bit smaller, anybody knows if somebody sells oversize crownraces or why by magic the fork kind'a shrink or something??? 1st time happens to me so I'm trying to find a logical reason for this.

I found an old dura ace headset and the crownrace does the same so doubt im doing something wrong. The original headset was a 105 from 92' or something like that.

Thanks.
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Old 12-01-10, 10:52 PM   #2
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Easy, easy fix use old fashioned mechanic creativity. Here are 2 ways.

For the first, you'll need a center punch, hammer and some body filler.

Use the hammer and punch to make a series of dimples 1/4" apart all the way around. Punching raises the metal into little volcanos which will provide the interference needed. For the short term, that's all that's needed, but pounding will mash the metal down causing looseness over time.

To make it more permanent, put some body filler onto the crown and press the race on while it's partly set, squeezing the excess out underneath. The raised cones will properly locate and support the race, and once it's set the body filler will give enough strength to make a durable job of it.

----

If the fit is only marginally loose, ie no play, but the race can be pulled off by hand, simply paint the crown seat area with a coat or two of a decent enamel paint. Make sure each coat is properly cured, and use a caliper to check size. Don't get carried away, a thin coat works, but if you build it up too far the race will shave it back off as it's pressed on.

Back in the bronze age I used to use "liquid paper" correction fluid for this job with good success rates, but since nobody types real-time anymore, I don't know if the stuff is still made.
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Old 12-01-10, 10:57 PM   #3
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Hmmm i thought in something similar a few minutes ago... Thanks a lot FB.... some solution for the long term? maybe add some brass to it?

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Old 12-01-10, 11:04 PM   #4
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.... some solution for the long term? maybe add some brass to it?
Overkill, and increases the odds of a cock-up. Keep it simple. Raising the metal alone will last a few years, with the body filler it'll outlast the bike.
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Old 12-01-10, 11:08 PM   #5
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Cool thanks... hope I dont screw up the fork now


Thanks for the extra tips, yes it comes lose but wonder if after getting all the paint it will shim it right, actually we are talking maybe of going from 26.2 to 26.4 so maybe the paint job will keep the race in place just fine...

Thanks.

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Old 12-02-10, 08:54 AM   #6
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This is a pretty common problem. The center punch idea previously mentioned works good. I've not used body filler before, but Loctite 640 works very well: http://www.emisupply.com/catalog/loc...term=LOC-37484

Another good option is to see if your local bike shop has a Stein Knurling tool, which is designed specifically for this issue: http://www.ride-this.com/index.php/s...ource=googleps . If they do, they can knurl it for you in a matter of minutes for a few $.

Knurl it and loctite it and it will likely never come loose....

Dave
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Old 12-02-10, 09:46 AM   #7
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I have not seen this before, thanks for sharing
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Old 12-03-10, 04:39 PM   #8
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Thanks a lot dave...I'll ask around, Well I finished the fork paint job so in a few days i'll check the fit if the crown race once the clear is hard to the touch.
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Old 12-03-10, 10:34 PM   #9
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Are you sure the crown race is not 27.0mm, sitting on a 26.4 fork crown?
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Old 12-04-10, 02:03 PM   #10
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Are you sure the crown race is not 27.0mm, sitting on a 26.4 fork crown?
i was thinking the same thing, but this brother says he's measured the thing, and even dealing with 6tenths of a mm, i think he might notice. Plus, he's feelin sorta shhh-sure that the race is 26.4, so i'm thinking that's printed on the packaging.

in a related story, i have an old b-stone with a 27.0 fork crown race. I rebuilt and re-used the original headset, and i'll be darned if the thing isn't a wee bit loose. Not loose-as-a-goose, but you can pull it off by hand if you've got a nice grip. I just put it together, tightened everything down proper, and it seems to hold just fine.

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Old 12-04-10, 06:53 PM   #11
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A slip-fit that's firm but can be pulled off by hand as surreal describes, usually doesn't cause any noticeable effect. It might contribute to high speed vibration of vibration when braking, depending on how much actual movement is possible.

But it shouldn't be ignored, the race will move on the fork wearing the seat, and eventually the problem will get worse. For zero-movement loose fits, a bit of bearing retaining adhesive, ie. Loktite, or even a bit of paint will do the trick. If there's actual play, then you need to build up crown diameter by Knurling or using a center punch.
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Old 12-04-10, 07:56 PM   #12
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i'll pull the fork and loctite it,just in case. thanks!

=rob
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Old 12-04-10, 09:03 PM   #13
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i'll pull the fork and loctite it,just in case. thanks!

=rob
Use a low strength grade, you just want to keep it from spinning, but you want to be able to remove it later.
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Old 12-17-10, 11:13 AM   #14
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Hi... update, yesterday took the bike to the shop for facing the headtube/bb and crownrace and all perfect, the paint basically hold the crown race w/o any problems.

Thanks
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