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How bad is this fork damage?

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How bad is this fork damage?

Old 06-03-17, 09:20 AM
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FE11244
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How bad is this fork damage?

Hello,

The headset on my 80s steel frame racing bike was refusing to tighten so I thought I'd disassemble it and clean everything up, since as far as I'm aware this has never been done on this bike.

After I managed to prise the stem from the fork I had a look at everything and noticed this damage to the fork, at the bottom of the steerer. (Images attached).

Looks as if the metal has chipped away or corroded?

Can you tell me how bad this is and if I will be able to remedy it at all?

My goal is to fix up the bike myself while spending as little as I can, so I'd really rather avoid having to buy a new fork.

Thanks for all your help.

(I'm still quite new to bicycle mechanics)

Best,

Francis
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Old 06-03-17, 09:37 AM
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jimc101
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Is that the crown race? (the bit between with the damage, above the fork crown (looks a bit large, but had a quick look at a old 531 fork I have, and it has nothing like that)

Thinking you should be able to knock that section off with a drift, and fit a new crown race (you may need a new headset if an identical replacement isn't available)
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Old 06-03-17, 10:06 AM
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Originally Posted by jimc101 View Post
Is that the crown race? (the bit between with the damage, above the fork crown (looks a bit large, but had a quick look at a old 531 fork I have, and it has nothing like that)

Thinking you should be able to knock that section off with a drift, and fit a new crown race (you may need a new headset if an identical replacement isn't available)
Thanks for the response, yes I've just knocked that off, and I can confirm the damage/corrosion is on the fork crown (image attached).

Do you think this causes any practical issue, or is this the end of this fork? (I really hope not).

Thanks again,

Francis
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Old 06-03-17, 10:44 AM
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.
...the majority of your crown race seat appears to be intact, and in pretty good shape. Since the purpose of it is to provide a firm seat for the crown race, which bears the load through your headset bearings, it looks to me like you're in pretty good shape.

If there was a lot of corrosion, you might consider a new headset, and certainly new bearings, if you re-use the old one.


Not sure about your "refusing to tighten" issue...........that could refer to a lot of things. Check the threading in the headset and on the fork itself. If it strips, it usually strips inside the headset, but all things are possible in the best of all possible worlds.
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Old 06-03-17, 10:45 AM
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The fork looks ok from the pics. I'm not seeing a lot of "corrosion". I'm seeing a weld (maybe a little rough) that was turned on a lathe to provide a proper spot for mounting your bearing race.

How was your fork "refusing to tighten"? If you had all the parts and spacers and bearings installed and the steerer tube was pulling away from the fork crown due to corrosion, and when you tighten the locknut as far as it will go, and still not getting the bearings loaded,, the the fork is toast. If you are missing a part, or if the threads need to be chased (or alternately, have the rust brushed out with a stiff steel brush), then you need to make sure you get the right parts and clean up the threads.

Could it be that you cross threaded the locknut (that is, screwed it on at an angle and not straight)? If not too bad, this can be fixed by chasing the threads. Your LBS should be able to do this.

Well, 3alarmer beat me to the punch. But I note we are giving almost the same assessment and advice - do with this what you will. Good luck.
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Old 06-03-17, 10:54 AM
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I don't see any current damage at all.
All I see is a somewhat sloppy line on an uncritical item.
If my interpretation of the pic is right, I'd have no worries about riding that fork.
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Old 06-04-17, 03:34 AM
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Fork thread type?

Thanks for everyone's input.

Originally Posted by WizardOfBoz View Post
How was your fork "refusing to tighten"? If you had all the parts and spacers and bearings installed and the steerer tube was pulling away from the fork crown due to corrosion, and when you tighten the locknut as far as it will go, and still not getting the bearings loaded,, the the fork is toast. If you are missing a part, or if the threads need to be chased (or alternately, have the rust brushed out with a stiff steel brush), then you need to make sure you get the right parts and clean up the threads.
It looks as though the threads on the fork are a little out of shape, so the lock nut has not been engaging.

I'd like to try and fix this myself with a thread file, but before I do that I need to know what kind of thread I'm dealing with. Would you know the answer to this? The bike is a mid 80s bianchi.

Cheers,

F
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Old 06-04-17, 07:15 AM
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Originally Posted by FE11244 View Post
It looks as though the threads on the fork are a little out of shape, so the lock nut has not been engaging.

I'd like to try and fix this myself with a thread file, but before I do that I need to know what kind of thread I'm dealing with. Would you know the answer to this? The bike is a mid 80s bianchi.
Assuming you have the original fork, both Japan-built and Italy-built Bianchis will have 1" x 24tpi thread. An Italian built fork may have a 55 thread profile rather than 60, but it's still 24tpi.
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Old 06-04-17, 08:48 AM
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Originally Posted by FE11244 View Post
It looks as though the threads on the fork are a little out of shape, so the lock nut has not been engaging.

I'd like to try and fix this myself with a thread file, but before I do that I need to know what kind of thread I'm dealing with. Would you know the answer to this? The bike is a mid 80s bianchi.
Well, this could be the best possible news wrt the fork. Not sure how you could check for 55 vs 60 without an optical comparator, so maybe someone here can give you a definitive answer for a mid-80s Bianchi. As I suspect you know, a 60 thread chasing file will knock down the thread crown a bit. Probably not too big a deal for this thread - the major thrust on the fork is not downward and you are probably only chasing the first few threads. If the thread is 55, and you are as compulsive as I am, you'll want a thread file for Whitworth threads. Expensive. There is one for sale here:

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Old 06-04-17, 08:54 AM
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Originally Posted by WizardOfBoz View Post
Well, this could be the best possible news wrt the fork. Not sure how you could check for 55 vs 60 without an optical comparator, so maybe someone here can give you a definitive answer for a mid-80s Bianchi. As I suspect you know, a 60 thread chasing file will knock down the thread crown a bit. Probably not too big a deal for this thread - the major thrust on the fork is not downward and you are probably only chasing the first few threads. If the thread is 55, and you are as compulsive as I am, you'll want a thread file for Whitworth threads. Expensive. There is one for sale here:


Just a thought.
Why not just get a die to fit the fork steer tube and chase the threads that way?
Might be a whole lot less expensive than the thread file.
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Old 06-04-17, 08:56 AM
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Originally Posted by WizardOfBoz View Post
...you'll want a thread file for (Whitworth) threads. Expensive.
Wow! That *is* dear!. I bought a similar tool many years ago for metric threads. It has come in very handy on those rare occasions. I paid about $8 for it.

BTW, for a few bunged-up threads on a steerer tube I'd be more concerned about the pitch more than anything else. If you couldn't get a file with the right pitch, a very thin knife-edge file could be used cautiously.
Steve
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Old 06-04-17, 09:05 AM
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Am thinking this might work:

1" - 24 Right hand Thread Die 1 - 24 TPI | eBay
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Old 06-04-17, 09:15 AM
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Concur with Steve. If you're just restoring the last few threads so the locknut can get started, you probably can do a very nice job with a 60 24 tpi file. Go light, minimalism is the key here. The good part is that you are probably not going to need to unscrew the locknut again for years once you get it properly installed. So you don't need to go all "tool and diemaker" on these threads. If you have a good steady hand, a knife edge file would suit. A good one is not cheap, either (a Grobet 31.187 is about 25 bucks) but they are well-made and probably will allow you to get a good thread more easily.

The suggestion to use a die is natural and reasonable, but there are problems. First, one must use a rethreading die (often hex shaped) to repair threads, not a threading die (usually round). They're different animals. You'd have to be able to be sure to get the die on straight, and with the first few threads messed up this could be very difficult. Especially with a thread cutting (and not resthreading) die you could easily end up cutting a whole new thread pattern that is minorly crossways with the original, and not perpendicular to the steer tube axis, ruining the fork. A thread restoring (or chasing) file is the best tool here because you can start by using good threads to guide the file at the proper angle and position through the bad threads.

A rethreading die for 1x24 is here.

They look like this:

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Old 06-04-17, 09:34 AM
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OP, are you sure that the lock nut is not bottoming out on the top of the fork? I have seen instances where someone removes a reflector bracket, cable hangar, or other "unnecessary" piece and then the lip of the locknut hits the top of the threads because there is no longer the right number of spacers in the headset stack.
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