Bicycle Mechanics - Crown Race

I need to get a headset for the Fuji Supreme I am working on.
Tange seems to be a good price/quality choice.
But, what is the difference between Tange Levin and Tange Passage models?
Which size would I need 26.4 or 27 for the crown race? What is the place of measurement for the 26.4 or 27 spec?
Actually, I only need the threaded ring that is about 6mm high and is knurled as that is the most rusted part. Wonder if i can get that alone. I see the steel top nut sold alone on Amazon by Niagra CW.
http://media.use.com/images/s_1/44fb2416c0d3e84f7fcf.jpg (http://www.use.com/44fb2416c0d3e84f7fcf)
Thanks

Headset parts are seldom available separately these days. If you do need to replace the crown race, you will need to measure the inside diameter of the crown race (dimension "L" below):

http://os2.dhs.org/~john/headset.jpg

I don't have the means to measure the dimension 'L'. Even if I take it out, the difference betwen 26.4mm and 27 is very small. I wonder if a Fuji expert can tell me whether I need 26.4 or 27 size. I may not replace the crown race, if I get a new headset, if I can get away with it. Though, I have done it once and it is not that difficult.

the difference between 26.4 and 27 may seem small but it takes alot of filing to make it work.
also even if you aonly use them a few times a year a nice pair of digital calipers is a great investment. I just bought a set (I have had a standard non digital set for years) at harbor freight for 18$.
I bet Tmar knows or maybe scottrider

I don't have the means to measure the dimension 'L'. Even if I take it out, the difference betwen 26.4mm and 27 is very small. I wonder if a Fuji expert can tell me whether I need 26.4 or 27 size. I may not replace the crown race, if I get a new headset, if I can get away with it. Though, I have done it once and it is not that difficult.
If you can find an identical headset to replace the worn parts on your current one, you will not need to change the crown race (assuming it is in decent condition). Otherwise, there is no substitute for measurement. Japanese headsets of that era were available in both JIS and ISO dimensions.

the difference between 26.4 and 27 may seem small but it takes a lot of filing to make it work.
Yes, that is why I am trying to find out which one should I get. I meant that the diff is too small to measure with a ruler.


also even if you only use them a few times a year a nice pair of digital calipers is a great investment. I just bought a set (I have had a standard non digital set for years) at harbor freight for 18$.
I bet Tmar knows or maybe scottrider
I was thinking of doing just that. Looks like they work good for you. I am having a bad experience with a buffing kit I got from there a couple of weeks ago. The buffing compound seems to have hardened up and the little cloth wheel disintegrates when I try to buff an aluminum stem.

Everyone always recommends a set of digital calipers, but unless you've got bad eyesight or own a battery factory just get the standard one... and when you go to use it in 2 years it will still work.

Crown races are not universal even among the various models by a given manufacturter. Depending on the age or model of your frame it could be ISO (26.4 mm) or JIS (27.0).

Since "close enough" isn't good enough, take the fork to a bike shop and have them remove and measure the crown race. Then you will know what you have for future use.