Brompton headset issue

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nirakaro
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Joined: 22 Dec 2007, 2:01am

Brompton headset issue

Post by nirakaro »

I'm servicing the headset on the Brompton, and the wee plastic seal at the bottom is broken. It's not available as a separate spare part, and I'm reluctant to thole a whole new headset to get one.
IIRC, other headsets I've worked on don't have a seal at the bottom, so would I be ok to just reassemble it without the seal? (I realise that the lower bearing may deteriorate faster, but it's not going to do a high mileage.)
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simonineaston
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Re: Brompton headset issue

Post by simonineaston »

I've no experience of servicing this part myself, but i) all the kits I can find have the seal included and ii) Brompton design seems to include as a rule all that you need & nothing you don't, so my conclusion is that the seal is an important part of the assembly.
screenshot of headset kit
screenshot of headset kit
S
(on the look out for Armageddon, on board a Brompton nano & ever-changing Moultons)
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531colin
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Re: Brompton headset issue

Post by 531colin »

If the bike has mudguards, and isn't stored upside down in the rain, it will be OK
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simonineaston
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Re: Brompton headset issue

Post by simonineaston »

and a big splodge of grease :) If it were me, I'd just stick the seal back in, broken or not.
S
(on the look out for Armageddon, on board a Brompton nano & ever-changing Moultons)
nirakaro
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Re: Brompton headset issue

Post by nirakaro »

simonineaston wrote: 30 Jan 2023, 11:11am If it were me, I'd just stick the seal back in, broken or not.
I tried that, but it came out (being broken), causing several millimetres of play in the headset.
rogerzilla
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Re: Brompton headset issue

Post by rogerzilla »

The seal should not affect headset play at all.
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simonineaston
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Re: Brompton headset issue

Post by simonineaston »

as above... sounds like some further scrutiny is needed.
S
(on the look out for Armageddon, on board a Brompton nano & ever-changing Moultons)
nirakaro
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Joined: 22 Dec 2007, 2:01am

Re: Brompton headset issue

Post by nirakaro »

Ah, right – I reassembled it as I found it, with the seal below the fixed bearing on the fork. A look on Youtube shows me it should have been above the bearing – must have been reassembled wrong in the past.
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simonineaston
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Re: Brompton headset issue

Post by simonineaston »

That fits with this exert from a Brompton trade guide:
Remove the seal and tap the fixed bearing off the fork crown. Fit the new fixed bearing (ensure that the bearing is fully pressed home onto the top of the crown): fit the seal. Drive out the old bearing cups on the front frame, and press in the new bearing cups, fully home, and square. Fill both cups with grease.
However I have no idea if the guide is on the subject of the headset fitted to the bike in question. https://trade.brompton.com/Uploads/QPar ... eadset.pdf
S
(on the look out for Armageddon, on board a Brompton nano & ever-changing Moultons)
nirakaro
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Re: Brompton headset issue

Post by nirakaro »

I'm struggling to grasp what this seal is achieving. I'd imagined it was to stop weather getting into the bearing from below. But it sits on the steerer above the lower bearing? Closing the gap between the steerer and the head tube? Why would anything come down there? The upper bearing and the top of the steerer are already well sealed. Am I being stupid? Missing something?
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simonineaston
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Re: Brompton headset issue

Post by simonineaston »

Best advice I can offer is to suggest you ask Brompton - or the very excellent folk at Brilliant Bikes might be amenable to that sort of enquiry.
S
(on the look out for Armageddon, on board a Brompton nano & ever-changing Moultons)
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