headset cup won't stay pressed in headtube - potential to damage frame b riding
By:admin
This should be my last headset post. Thanks to those who have stuck with me through a variety of rather specific questions.
I removed the original 105 balls-with-retainers headset from the Centurion that I bought on eBay, because I couldn't get the headset adjusted without play, unless I tightened it to where it would barely turn.
After I removed the headset cups from the frame, I played around with the headset and realized that I'd had the plastic seals on backwards, and if I flipped them around everything was fine. Foiled by 1mm of plastic!
Anyway, I'd used a dry rag to clean off paint chips from the cups and the inside of the headtube, and when I re-pressed the headset cups, the bottom cup won't stay in the frame. It's not loose when it's in there - there's no play - but the cup doesn't press tightely enough into the frame to hold itself there against gravity. I was surprised, because all I'd done is cleaned up some paint chips with a rag. Also, the headtube and cup are not ovalized - I can turn the bearing cup as it's in the frame, with constant (albeit little) resistance.
I ended up just pressing the cups (top cup pressed in just fine, won't come back out of its own accord) and adjusting the headset. There's no play at all, no knocking when I lift the front wheel off the ground and drop it. Nothing. So it appears that the bearing cup fits just tightly enough in the frame that there's no play, and thus no danger to messing up the frame, but not tight enough to hold itself in there.
I don't think this will be a problem; everything is adjusted perfectly, and the bearings are thus keeping the cup from falling out. I'm just wondering if there's an outside chance that this could damage the frame. My default assumption is that it won't. Thanks for any feedback.
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I would take out the cup(s) and knurl them so they fit. You can take it to a machine shop and have it done professionally, but I would do it myself.
Find a piece of tube that the cup fits loosely over. Put the tube in a sturdy vise, slide the part of the cup that fits in the frame over the tube first. Now take a sharp cold chisel and whack some cuts into the part of the cup that fits into the frame. (If its aluminum, take it easy!). I'd start with about 6 cuts equidistant around the lip. Test for fit. If its too tight, file down some of the cuts, if it too loose, make some more cuts.
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Get some Loctite Grade 609 meant for bearing and cylindrical fit retention, including pressed cups. It's green but there are several green Loctite grades so be sure you get the correct grade number. It's medium strength and will fill small gaps.
This will absolutely retain the headset cup and prevent any headtube damage. It may require moderate heat to disassemble so plan on keeping the headset for a while.
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I second both of the above. I think I remember using a knurling tool when I worked at Franklin St. Cycles, so you should check to see if they have one. I'm pretty sure they do.
Loctite sleeve retainer works like a champ as well.
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Inspect the bottom of the headtube very carefully for cracks first.
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Weird thing is, I'd temporarily installed cups for an XT sealed-bearing threaded headset before realizing that the 105 was okay, I just needed to flip the seals. And the XT headset cups pressed in, and were tight, as they're supposed to be. So I think the headtube is fine. No cracks that I can see from the outside.
Also, the cup isn't loose, to the extent that there's no play. It's not moving around in the headtube at all. But neither is it tight.
I may use the loctite solution, but for the time being I think I'm going to ride the bike and just keep a close eye on it. So long as the headset is adjusted correctly, the cup ain't going to fall out.
white lobster, when did you work at Franklin St. Cycles? I live two blocks from there.
(锕侊箒)~~~~---------------------------------------------------------------------- Originally Posted by timcupery
Weird thing is, I'd temporarily installed cups for an XT sealed-bearing threaded headset before realizing that the 105 was okay, I just needed to flip the seals. And the XT headset cups pressed in, and were tight, as they're supposed to be. So I think the headtube is fine. No cracks that I can see from the outside.
Perhaps that XT headset was slightly larger in diameter than the 105 and has stretched the head tube.
Originally Posted by timcupery
Weird thing is, I'd temporarily installed cups for an XT sealed-bearing threaded headset before realizing that the 105 was okay, I just needed to flip the seals. And the XT headset cups pressed in, and were tight, as they're supposed to be. So I think the headtube is fine. No cracks that I can see from the outside.
Perhaps that XT headset was slightly larger in diameter than the 105 and has stretched the head tube.
