headset reinstallation

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thelawnet
Posts: 2278
Joined: 27 Aug 2010, 12:56am

headset reinstallation

Postby thelawnet » 20 Jan 2020, 5:49am

I seem to have made a bit of a dog's breakfast out of this.

I have this stack of parts
IMG_20200120_124142.jpg


i.e. top cap, 4 spacers, rubber seal, mysterious bolt with number 4 on the top, a silver metal ring I think the compression ring which looks snapped but probably is supposed to be like that?, and two other black metal parts I'm not sure the name of.

They all kind of came apart so I am not quite sure where everything goes, especially the bolt.


Can anyone explain where everything is supposed to go? I think there is nothing between the fork crown and the bottom of the head tube?
Image Attachments
IMG_20200120_124709.jpg
IMG_20200120_123306.jpg
IMG_20200120_123313.jpg

thelawnet
Posts: 2278
Joined: 27 Aug 2010, 12:56am

Re: headset reinstallation

Postby thelawnet » 20 Jan 2020, 6:22am

hmm perhaps it was just a phantom bolt that happened to be on the ground. only odd thing is that it seemed to have a decent bit of grease on it to have been there very long.

anyway have reassembled it seems ok except for the rubber seal which seems not quite right in that it is bulging out a bit.

IMG_20200120_131643.jpg

also perhaps the head tube needs to be pushed down a bit more as there is a tiny bit of daylight there

IMG_20200120_132101.jpg

peetee
Posts: 1646
Joined: 4 May 2010, 10:20pm
Location: Cornwall

Re: headset reinstallation

Postby peetee » 20 Jan 2020, 9:45am

Correct order is highly likely to be:
Silver split ring, thin side down ( it centres the bearing).
Thin seal (Check which way up by mating it to bearing top cap, bottom centre of photo).
Thick stack, centre of photo.
Stem/spacers shuffled to get correct handlebar height.

Big bolt is a red herring.
Check here and there fit any wafer thin shims. If found they go just above the split ring.
The Allen bolt goes through the top cap into the star.
When tightening the bike should be on the floor with stem clamp bolts just loose enough so the stem can be turned freely but not so loose it would spin or you can feel any play. With one hand hold the front brake lever so the bike can be moved back and forth pulling the brake momentarily. Tweek the top cap bolt til no rocking or clonking can be felt when the brake is applied. Lift the front wheel and turn the steering to check for binding. If it doesn't bind or clonk tighten the stem clamp bolts. If it does one or the other and no adjustment removes the issue then there is a shim missing or the headset needs replacing.
Current status report:
Back on two wheels in deepest Pastyland and loving every minute. Mission: to enjoy big, bad hills again.

Keezx
Posts: 421
Joined: 20 Dec 2014, 10:44am
Location: The Netherlands

Re: headset reinstallation

Postby Keezx » 20 Jan 2020, 10:30am

Missing on the picture in post no. 1 is a centering ring , which comes on top of the upper bearing.
Without it , there will allways be lateral play in the assembly (top part)

Marcus Aurelius
Posts: 742
Joined: 1 Feb 2018, 10:20am

Re: headset reinstallation

Postby Marcus Aurelius » 20 Jan 2020, 11:49am

You have it as it should be. The tolerances of replacement bits, can be a bit iffy though. If you’ve pre tensioned the headset, as far as you can and there is still a bit of play, you could try putting a 3 or 5 mm headset spacer between the top of the stem and the top cap. This will give you some more space to increase the headset tension sufficiently, to eliminate any play. And when your checking for play, turn the wheel 90 degrees, and push back and forth, that way you can’t be confusing movement in the brakes / wheel, with headset play.

slowster
Posts: 1137
Joined: 7 Jul 2017, 10:37am

Re: headset reinstallation

Postby slowster » 20 Jan 2020, 11:59am

thelawnet wrote:it seems ok except for the rubber seal which seems not quite right in that it is bulging out a bit.

Maybe that is indeed how the manufacturer designed it to be assembled, but that seems wrong to me. If the seal is visibly bulging out, then presumably it is being compressed when the headset is being adjusted by tightening the bolt to preload the bearing. That surely cannot be right (?) because as braking forces were applied and removed the seal would compress further and expand fore and aft, i.e. its elastic/compressible nature would create (damped) play in the headset when riding and braking.

I would expect the internal diameter of the seal to be wide enough that there was no rubber directly in between the (incompressible) metal surfaces of the top cover above and tapered ring below. The diagram on page 2 of of this guide to Hope headsets probably illustrates that better than my explanation. Hope supply optional shims to install underneath the (slightly conical) seal to allow fine tuning of the gap around the edge of the seal.

It's difficult for me to tell from the photographs, but is the seal thin/flat in section?
Last edited by slowster on 20 Jan 2020, 12:27pm, edited 2 times in total.

peetee
Posts: 1646
Joined: 4 May 2010, 10:20pm
Location: Cornwall

Re: headset reinstallation

Postby peetee » 20 Jan 2020, 12:00pm

Keezx wrote:Missing on the picture in post no. 1 is a centering ring , which comes on top of the upper bearing.
Without it , there will allways be lateral play in the assembly (top part)

I believe it's silver, shown in pic 3 upside down
Current status report:
Back on two wheels in deepest Pastyland and loving every minute. Mission: to enjoy big, bad hills again.

Valbrona
Posts: 2258
Joined: 7 Feb 2011, 4:49pm

Re: headset reinstallation

Postby Valbrona » 20 Jan 2020, 6:25pm

thelawnet wrote:also perhaps the head tube needs to be pushed down a bit more as there is a tiny bit of daylight there

[img]IMG_20200120_132101.jpg[/img]


Two things influence the size of the gap you see:-

- the stack height of the bearing. Sometimes you can get the 'same' bearing in different stack heights.

- the exact machining of the inside of the headtube. This, of course, cannot be changed.

No daylight whatsoever and your fork may not turn on account of the contact between head tube and fork crown.
I should coco.

tim-b
Posts: 1146
Joined: 10 Oct 2009, 8:20am

Re: headset reinstallation

Postby tim-b » 20 Jan 2020, 8:01pm

Hi
There's a picture of the headset stack here (link)
The upper and lower head tube races are incorporated in your frame design and won't be present.
The spacers are fitted between the upper bearing cover (labelled "seal") and the handlebar stem.
The crown race is sometimes incorporated in the fork steerer tube, and more often is a separate ring on the fork crown.
The compression ring is usually (always?) split, the crown race is often split, but could be a complete ring.
The bolt looks very short to me, and the ring-shaped seal is usually incorporated under the upper bearing cover
Assembly/servicing information link
I can't see any bearings, these might be stuck in the upper and lower headtube sections
Regards
tim-b
~~~~¯\(ツ)/¯~~~~

gregoryoftours
Posts: 1049
Joined: 22 May 2011, 7:14pm

Re: headset reinstallation

Postby gregoryoftours » 20 Jan 2020, 9:13pm

It looks like your upper part of the headset is semi integrated. It's a bit hard to see the exact shape of all the parts clearly but I would expect the upper assembly to go together in this order
IMG_20200120_203954.jpg
:assuming that the upper bearing is already in the top of the headtube 1 goes beveled side down (is upside down in this photo :
IMG_20200120_211503.jpg

It is supposed to be split as it is. Then part 2 flat side down, slightly beveled side up (sometimes a very thin shim or two underneath part 2 if it binds on the headtube) , 3 with groove facing up, 4 sitting in the groove on top of 3. Then spacers 5, stem and top cap 6 as usual. If part 3 stops part 4 from sitting as low as it would otherwise do, or if the outer edge of 4 doesn't fit into the groove of 3 cleanly I think it may not be a part of that headset, or it might be fitted in a different place so that part 1 or 2 sits into it. The lower half of the headset is fully integrated so the lower bearing fits directly into the head tube and the fork directly into the bearing. The small gap between the fork and the bottom of the head tube is a normal amount of clearance. The bolt is definitely not a part of the headset