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Discussion Starter · #1 ·
I'll keep this short.

Still have headset loosening problems. On inspection over time, I think the expander plug is "pulling up" through the (carbon) steer tube. Really! I'm floored. And highly perturbed after mucking around with this issue for God knows how long.

Sending the forks back to De Rosa (who are notoriously slow and not hassle-free when it comes to honoring warranties..esp since I got this bike on fleabay) is really not something I want to hassle with, just to have them tell me some four months from now that I will need to pay $xxxx to fix it, or buy new forks.

I'd rather buy new forks/headset now, or find someone who is an expert in removing/replacing expander plugs in a gawldang carbon steer tube without exploding it. Yeah I know, good luck. :(

Any of y'all have any good leads?
 

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old school drop out
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If the headset can be adjusted properly, but later becomes loose, the expander plug is not the issue. The top cap assembly can be completely removed from your bike and the headset should stay adjusted - the stem maintains the bearing pre-load.

When exactly is the headset loosening?
 

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Agree with laffeaux. If the headset is "coming loose", chances are that it was never tightened properly to begin with. The drill nowadays is to tighten the headset until it begins to bind up, then back off 1/4 turn or so. Old-timey mechanics often tighten the headset until there's no play. But with modern headsets, that's not enough—you need to go way beyond that point for proper preload. FWIW, if the expander plug "pulls up", you should never have gotten proper pre-load to begin with.
 

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Discussion Starter · #4 ·
laffeaux said:
If the headset can be adjusted properly, but later becomes loose, the expander plug is not the issue. The top cap assembly can be completely removed from your bike and the headset should stay adjusted - the stem maintains the bearing pre-load.

When exactly is the headset loosening?

Thanks laffeaux. Interesting.

The headset loosens when sufficient torque is applied. This means, either heavy braking on a downhill, or pulling on the bars going uphill. There is a "pop"and I then know the headset has come undone again. I have to take everything apart, re-seat the plastic washer and tighten it all back up again.

Another poster in a different forum suggested the stem may be slipping. De Rosa has stated they've had issues with the carbon top cap being too flexy.

I'll need to measure the expander plug to make sure I'm not "seeing things" but I swear there is more demarkation on the bolt (suggesting the plug is moving) and less space between the plug and the top of the steer tube.

Thanks for your help.
 

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Discussion Starter · #5 ·
wim said:
Agree with laffeaux. If the headset is "coming loose", chances are that it was never tightened properly to begin with. The drill is to tighten the headset until it begins to bind up, then back off 1/4 turn or so. Old-timey mechanics often tighten the headset until there's no play. But with modern headsets, that's not enough—you need to go way beyond that point for proper preload. FWIW, if the expander plug "pulls up", you should never have gotten proper pre-load to begin with.

Again, interesting. I may have to bite the bullet and get a torque wrench. I've been using the "Old-timey" method you've described, but it's not working. Thought we had it fixed with new top cap, but no.

It rides fine for a while, then "pop" out she goes at the most inopportune moments.. :(
 

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OldEndicottHiway said:
I may have to bite the bullet and get a torque wrench.
Torque wrench is useless for that. Tighten the top cap / top cap bolt until left or right front wheel flop is sluggish when tilting the off-the-ground front end of the bike. Then back the top cap / top cap bolt off 1/4 of a turn. Check front wheel flop again. If still sluggish, back off another 1/4 turn.
 

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Discussion Starter · #7 ·
wim said:
Torque wrench is useless for that. Tighten the top cap until left or right front wheel flop is sluggish when tilting the off-the-ground front end of the bike. Then back the top cap bolt off 1/4 of a turn. Check front wheel flop again. If still sluggish, back off another 1/4 turn.

Thank you. Will try this. Anything is better than spending $$ on repairs that are not necessary.
 

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wim said:
Torque wrench is useless for that.
I'm not sure about that - especially if either the stem or steerer is carbon. If the stem bolts aren't properly tensioned there is a risk of the stem slipping on (or crushing) the steerer.
 

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sounds like stem...

agree with laffeaux and wim - if the headset is ok for a while and then goes 'wrong' it sounds more like the stem is slipping - securing the stem once headset compression is set is what holds it all in place (theoretically you could be able to ride without the top cap in place at all once the stem has been secured)

So I would be checking torque values on your stem tightening on the steerer. Do stem manufacturer/fork manufacturer have torque values, carbon bonding paste, grease/no grease recommendations you can follow?

Good luck, sounds like a real PITA!
 

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sometimerider said:
I'm not sure about that - especially if either the stem or steerer is carbon. If the stem bolts aren't properly tensioned there is a risk of the stem slipping on (or crushing) the steerer.
Correct. I wasn't clear—the reference to the useless torque wrench was supposed to be about setting pre-load (tightening the top cap bolt / top cap).
 

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Discussion Starter · #11 ·
charlieboy said:
agree with laffeaux and wim - if the headset is ok for a while and then goes 'wrong' it sounds more like the stem is slipping - securing the stem once headset compression is set is what holds it all in place (theoretically you could be able to ride without the top cap in place at all once the stem has been secured)

So I would be checking torque values on your stem tightening on the steerer. Do stem manufacturer/fork manufacturer have torque values, carbon bonding paste, grease/no grease recommendations you can follow?

Good luck, sounds like a real PITA!

Thanks CB and all. I don't know if it needs carbon paste...I thought that was for if you were joining two different materials? Sometime ago the owner/mechanic @ the LBS (he's a good one) got a hold of De Rosa to ensure all was as should be. Still, it popped out again.

PITA indeed! Ah well, it's the problems that force you to learn more, right? (trying to look on the bright side here).

Thank you all again for the help. .
 

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thoughts...

Something obvious is being overlooked. Are you certain that there is a gap between the steering tube and the top of the stem or the spacer on top of the stem? If there isn't you can tighten the top cap as tight as you want an never get the headset adjusted. The stem must be loose before the top cap is tightened.

If you think that the expanding plug is slipping, use a precision rule to measure the depth of insertion, then recheck if the problem reoccurs. It's the stem that holds the adjustment, so that's really what to look at. It won't hurt a thing to use carbon assembly paste and be absolutely sure that the stem bolts are tight enough. It sounds to me like the stem is simply not being tightened with enough force to keep it in place.

The idea of tightening the top cap until the fork drags when turned is good, but the amount to back off the top cap tension may be extremely small. Campy headsets do not have angular contact bearings like some other brands and are very sensitive to top cap pressure. IMO, backing off the bolt by 1/4 turn is way too much. That should be the difference between too tight and way too loose. Always recheck the play in the hedaset after the stem is tightened. If there's a big change, then the top or bottom surface of the stem may not be square to the bore.
 

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The others are right. The plug is only there to establish preload. Once the stem is tightened, it's no longer necessary.

So what could be causing it? Stem slip is a possibility. Is the lower fork race properly installed and fully seated? Are the bearing races in the frame integral or pressed in? If pressed, are they full seated. Is everything square? Lots of stuff to check there.
 

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Discussion Starter · #14 ·
Thanks C-40 and JoelS.

Yes, "lots of stuff to check" is right.

Googling everyone's input led me to Parktool's "do it yourself" site...omg. I'm dumbfounded at the complexities."Do it myself" my @ss.

Again, I highly appreciate everybody taking time out to help me with problem solving ideas, and I will put them to good use.
 

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C-40 said:
If there's a big change, then the top or bottom surface of the stem may not be square to the bore.
this happened a looooong time ago w/ Kore stems, i believe. had it happen on a few bikes and it didn't even occur to me that this could be the problem. finally figured it out while just sitting there staring at the damn thing. this could be it...
 

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Discussion Starter · #17 ·
C-40 said:
The idea of tightening the top cap until the fork drags when turned is good, but the amount to back off the top cap tension may be extremely small. Campy headsets do not have angular contact bearings like some other brands and are very sensitive to top cap pressure. IMO, backing off the bolt by 1/4 turn is way too much. That should be the difference between too tight and way too loose. Always recheck the play in the hedaset after the stem is tightened. If there's a big change, then the top or bottom surface of the stem may not be square to the bore.

Will one of you fine folks that understand "square to the bore" (you, cxwrench, mtbbmet) explain this? I don't understand.

I'm not quite sure what you mean by "big change" after tightening the stem. Isn't there always a lot of play before tightening?

Thanks for your patience.
 

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Square to the bore

What this means is that the upper and lower edge of the stem where the steerer tube of the fork passes through must be absolutely perpendicular to the bore through the stem. If the edges of the stem where they bear on the top of the headset are not perfectly square and seated flush on the bearing there may be some change in the preload of the headset bearings and hence the "clunk" and loose headset. The results are about the same as when the upper and lower faces of the headtube of the frame are not absolutely parallel and faced perpendicular to the bore axis of the head tube. The loads are uneven and things come loose.
 

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Yup. Also, the upper or lower bore of the stem could be slightly ovalized giving the steer tube some play inside the stems bore.
 

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OldEndicottHiway said:
I'm not quite sure what you mean by "big change" after tightening the stem. Isn't there always a lot of play before tightening?
Once you preload the cap, there should be no play at all. Then tighten the stem to the steerer tube (and torque it properly). If there is play after preloading the cap, there is something else wrong.

It occurs to me that if the top of the steerer tube is flush with the top of the stem, there's a good chance you won't be able to get sufficient preload on the bearings and will never get your headset tight. The top of the steerer tube should be inset a few mils inside the stem.
 
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