Tech advice...Brompton M6L

The Missus’ M6L has developed some play in the headset bearing. The steerer/can move to and fro a bit so im think the bearings need adjust. Can I simply unjam the 2 36mm rings from one another and snug-up the lower ring to properly seat the bearings into the races to take up the play?

Or....does the stem need to be removed first?

Any one? TIA
 
Location
Loch side.
No need to remove the stem.
 
Location
Loch side.
Can I simply unjam the 2 36mm rings from one another and snug-up the lower ring to properly seat the bearings into the races to take up the play?

That should do it.
Grease them at the same time is what I would do.
Yes. Grease and clean is always a good idea, although it is impossible to clean them without removing the stem and disassembling the headset.
 
OP
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FolderBeholder

Senior Member
Can I simply unjam the 2 36mm rings from one another and snug-up the lower ring to properly seat the bearings into the races to take up the play?

That should do it.
Grease them at the same time is what I would do.
Thank you for the info...(the bike is a 2018 model, purchased new and delivered in July of 2018 so I will check the grease but it shouldn’t really need it yet but then so shouldnt the headset bearings need attention) should I be wary of loose ball-bearings?
 
Location
Loch side.
Thank you for the info...(the bike is a 2018 model, purchased new and delivered in July of 2018 so I will check the grease but it shouldn’t really need it yet but then so shouldnt the headset bearings need attention) should I be wary of loose ball-bearings?
If it is that new and hadn't been ridden in the wet, the grease should be fine. No, don't worry about loose ball bearings. They have their advantages, and disadvantages.

Go for a ride and drink a beer.
 
OP
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FolderBeholder

Senior Member
When it is shot, Chris King Gripnuts are nice, virtually maintenance free.
I like those as I appreciate that type of craftsmanship and design....we’ve had these bikes just a few months though. The Bromptons have been rock-solid otherwise and we ride them almost daily.
 

berlinonaut

Senior Member
Thank you for the info...(the bike is a 2018 model, purchased new and delivered in July of 2018 so I will check the grease but it shouldn’t really need it yet but then so shouldnt the headset bearings need attention) should I be wary of loose ball-bearings?
It seems to be a bit of a common pattern of the headset coming loose on new Bromptons after a couple of months (or rather a couple of 100 kms). I had this on most of my own Bromptons and know a lot of people having had the same issue on theirs, though not everybody seems to be affected. I assume that the bearing carrier wears in a bit, at least this seems a logic explanation (though I never had that issue with any other bike using the same style of headset). Typically adjusting it once (or in rare cases two or three times) solves it basically forever. As with most people it seems to show up some time during the first year I'd assume it to be less of a time issue but depending from the distance ridden and maybe the surfaces involved as well. Possibly this is one of the topics that the free first service after three months targets at (which obviously only works if until then the bike has been ridden sufficiently for the effect to take place). So nothing to worry about.
 

rogerzilla

Legendary Member
They're not the best headsets, and I'm not sure Brompton do a good job of facing the head tube and fork crown at the factory, since this is the usual reason for a headset not being able to be adjusted properly. Unfortunately it's also a rather low stack height and therefore not many 1 1/8" threaded headsets will fit. I have a King 2Nut on mine but I had to cheat and grab 1.5mm more stack height by having the head tube aggressively faced.

The other fault these suffer from, at high mileage, is stretching of the head tube. I had an L3 that was about 9 years old, and the lower cup was very loose. Beware of any bike with pressed-in cups that isn't lugged or doesn't have reinforcing rings brazed around the top and bottom of the head tube! I fixed it with a suitable strong grade of Loctite.

Add it to the list of Brompton design faults they still haven't fixed after 30 years...

You should be able to adjust it without removing the stem, if the stem has been fitted properly according to Brompton's instructions. There should be a little daylight between the bottom of the stem and the locknut. If someone has pushed the stem right down when fitting it, you will not be able to undo the locknut without first pulling the stem up a bit. The stem wedge can take quite a hammer blow to make it drop.
 
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12boy

Veteran
Location
Casper WY USA
Rogerzilla, do you suppose the headset stretch could have been avoided if the headset hadn't loosened, or did this happen after you installed the King?
 

rogerzilla

Legendary Member
Rogerzilla, do you suppose the headset stretch could have been avoided if the headset hadn't loosened, or did this happen after you installed the King?
It was a different Brompton to the one wirh the King. I think it was just caused by high mileage. It's a known issue with lugless frames.
 
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