Gonzo Bob

It doesn't sound ovalized to me. He said the high resistance is constant. An ovalized headset gets tighter as you turn the fork.

jbone

You will not feel any difference is resistance when turning the fork if the head tube is ovalized. The tube is what is ovalized therefore the headset cups have a small amount of play in them. The cups are not ovalized so you have a circle sitting inside an oval and you need to fill that gap. That is why you put a shim in there, to take up that space and prevent the cups from moving back and forth. That is why he is still getting play no matter how tight the headset is. Chris King has made headsets with a 1" depth on them specifically for this purpose. The longer depth gets the headset beyond the ovalized portion of the headtube.

TallRider

Yeah, ovalization wouldn't make the resistance non-constant; it would just cause there to be resistance.
It seems, however, that the forces that caused the head tube to ovalize could have caused the upper part of the bearing cup (the part that fits in the frame) to ovalize with it. Especially if this part is aluminum. It won't cause the bearing cup itself to ovalize, because that's much wider and therefore exponentially stiffer.

mechBgon

Because one or both bearing retainers are upside down. That's where the smart money is on this one.

Try this: remove the fork. Leave the top headset parts in place. In this case, the cone is in the frame, the cup is on the part that's normally on the fork. Push down hard on the cup and try to turn it. Are the balls rolling?

Now set aside the top part of the headset. Flip the bike over. Drop the fork through the head tube and do likewise. Do this without the bearing seal in place, and you can peek into the headset as you forcefully push down on the bearing and turn it. Are the balls rolling?

TallRider

Nope, they're in correctly, as stated above. Top bearings spin smoothly and perfectly; resisntace is coming from the bottom even though the retainer is in correctly. I'll try the 2nd part of your suggestion, however, to see if the bearings are actually spinning. If they're not, though, it's not because the retainer is upside-down, but rather because either the crown race is too small, or the bearings are too small (a too-small crown-race could be rectified by larger bearings that fill up more space between crown race and bearing cup).

mechBgon

Errr... don't quit the day job. Using larger bearings than the races are designed for is the incorrect solution. If in doubt, get your LBS to look at it or slap the other headset in there.

edit: also, I believe the seal for that headset has an "L"-shaped cross section, so ensure that it's in the right way too. Good luck

TallRider

Good point; I've not done actual shop mechanic work for 10 years, but should have been able to figure that out with a little 3-D mental visualization. However, I was thinking there might be some chance the bottom race of the headset originally came with loose balls that are larger than the ones in the retainer that's in there right now. That's an alternate explanation to the looseness, if the crown-race is actually the original.
I've actually got lots of physics/engineering and biomechanics training and experience, and tested protopyte running shoes for Adidas and Mizuno during college, and did a bit of consulting for Nike on this stuff too.
I still think the main thing is that the crown-race is wrong and too small, for whatever reason. That's the only plausible explanation I can think of, though it's baffling how the wrong race would have gotten on the fork crown.
I've got a few headsets sitting around that I could replace this with, but if my LBS has the correct race sitting around (unlikely for a late-80's headset, but possible) I'll just have them replace that. Tools for installing and removing headsets aren't worth having for a home-mechanic, at least not one who works at low volume, just because of economies of scale.

coyotecrust

balls facing away from cups !!

in case anyone was embarrassed to ask.

DannoXYZ 

You can use big screwdriver and hammer to remove cups and the fork-crown race (tap lightly and move to opposite side). A headset press can be made with a big bolt and washers.

It's very possible that the original crown-race was pitted and they replaced it with another one that was laying around. If the diameter and curvature of the race doesn't match properly, the balls may not be rolling on the right spot leading to looseness. What you can do is test where the balls are rolling on the race.

Remove fork and wipe off all the grease from the crown-race. Remove the retainer/bearings and clean off all the grease from the cup, put retainer/bearings back in and wipe most of the grease off, there should be a bare minimum. Then stick in the fork, instlal adjustable cup to hold in place and spin it by hand around a couple times. Disassemble and inspect the track of grease showing where the balls rolled. You can also wipe it all down and use prussian-blue to make the trace as well.

The movement should be in the middle of the curved part. If it's too wide, that would mean the crown-race is too small in diameter for the cup. Larger bearings would help in this case. Also be aware that there's a difference between metric vs. SAE sized bearings...

Gonzo Bob

I didn't say "headtube" - I said "headset" in response to the poster who said "headset". The cone races *can* ovalize which results in increasing tightness as you turn the fork.

mechBgon

Also timcupery, if you could post a good close-up photo or two of the crown race...? A picture's worth a thousand words

TallRider

crown race is silver, and not pitted. I don't have time to take the thing apart for pictures right now. But the curvature of the crown race is slightly diff than the curvature of the race in the top of the headtube.
I'll get pictures if I get the time.

TallRider

Okay all, I figured out the problem. I'd flipped the headset seals. I'm surprised that very thin plastic could cause that much resistance when the bearings weren't tightened, but it did, and it does. I just replaced the headset last night, and put an XT threaded 1" with cartridge bearings in. Having the cups and bearing races of the old headset out allowed me to mess with them easier, and I noticed that the bearings fit perfectly (smooth spin, no play) when the headset seals were out, but not when they were in. Then I tried flipping the seals, and it worked.

So, feeling a bit stupid. But I guess no one here wondered about the seals either. I'm out $10 for the headset on eBay, and it's a better, lighter headset that should last a long time. And out $20 to build my own working-on-headset tools, but I'll use those in the future. And I've got a nice headset sitting around now. Mainly I'm out lots of time.

Not quitting my day job,

Tim