Headset cartridge Bearing-Shimano BC1-help please

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bikes4two
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Headset cartridge Bearing-Shimano BC1-help please

Postby bikes4two » 3 Mar 2019, 6:55pm

The lower cartridge bearing in my 1989 Dawes Galaxy has suffered water ingress and requires replacing but I am unable to find anything on the web when I search for "Shimano Cartridge Bearing BC1" or similar phrases.

There may be alternatives of course, but I do not know how such bearings are described. I have meaured the internal and external dimensions and the overall thickness, but I do not know what the angle of the bearing tapers are.

The cap covering the bearing cups says Shimano 105 if that helps?

"Shimano Cartridge Type Bearing BC1"
Internal diameter - 27mm/ 1.063"
External diameter - 41.7mm/1.642"
Thickness - 7.7mm/0.303"

Can these bearing be split and just the balls replaced? At a push I could put the top bearing on the bottom cups and re-grease the damaged one, but it is a bit rough at the moment.

All assistance/advice/information gratefully received - thank you.
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Shimano BC1.jpg
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Samuel D
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Re: Headset cartridge Bearing-Shimano BC1-help please

Postby Samuel D » 3 Mar 2019, 7:09pm

I believe you need Shimano part number 78V 9803. These are very hard to find because Shimano stopped making them. Cyclebasket had them until recently (just one in stock a couple of months ago) but they’re now sold out. I see it here for £25, but I have never heard of that shop so can’t vouch it.

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Mick F
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Re: Headset cartridge Bearing-Shimano BC1-help please

Postby Mick F » 3 Mar 2019, 7:11pm

Can't help specifically.
I have a headset with bearings similar to that and asked on here about replacements for them as and when they need replacing, as I too couldn't find them anywhere.

The advice was to buy a complete new headset and use the bearings from it. If all you need is just the one bearing, you'll have a spare.
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Re: Headset cartridge Bearing-Shimano BC1-help please

Postby fastpedaller » 3 Mar 2019, 7:33pm

Sounds like good advice... I once looked at the possibility of replacing bearings in a cartridge ST bottom bracket, but the bearings were more expensive that just buying the whole new item.

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bikes4two
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Re: Headset cartridge Bearing-Shimano BC1-help please

Postby bikes4two » 3 Mar 2019, 8:29pm

Samuel D wrote:I believe you need Shimano part number 78V 9803. These are very hard to find because Shimano stopped making them. Cyclebasket had them until recently (just one in stock a couple of months ago) but they’re now sold out. I see it here for £25, but I have never heard of that shop so can’t vouch it.



Thanks Sam, the picture in the link to bicyclist.cc at least shows that part# 78V 9803 is the part I'm looking for, but unfortunately they are out of stock too.

As MickF suggests, maybe the complete part leaving one for spare might be the way to go!

EDIT - just found some related info in this thread from Brucey - I'll see where that leads me!
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Samuel D
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Re: Headset cartridge Bearing-Shimano BC1-help please

Postby Samuel D » 3 Mar 2019, 9:11pm

bikes4two wrote:[Thanks Sam, the picture in the link to bicyclist.cc at least shows that part# 78V 9803 is the part I'm looking for, but unfortunately they are out of stock too.

That’s interesting because it said “in stock” when I posted. I wonder if another forum member who needed the bearing got to it before you.

gregoryoftours
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Re: Headset cartridge Bearing-Shimano BC1-help please

Postby gregoryoftours » 3 Mar 2019, 9:25pm

I take it that is one of the old threaded headsets in 1" variety? If you can't find the same headset or suitable replacement bearings there are plenty of decent quality ISO 1" threaded headsets around. You will have to watch out for stack height though as of 105s are quite short. If it's only the bottom half of the headset that needs replacing then any 1" ISO standard headset will do, threaded or threadless, just use the bottom bearing, cup and crown race.

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bikes4two
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Re: Headset cartridge Bearing-Shimano BC1-help please

Postby bikes4two » 3 Mar 2019, 10:32pm

I might be getting confused here in that I'm following various parts and part numbers and am wondering if I've arrived an equivalent part or not.

> In a post above my 'BC1' is PN 78V-9803
> in this post here (6th post down) Brucey links in a document plus other info which leads to 78V-9803 being the same as 787-9803
> 787-9803 appears to fit HP-M740, HP-M563, and HP-5500
> this in turn leads to another Shimano number, Y-78798030

Y78798030 is available from at least two German sites and another in the Far East - the big question is, can I have confidence that this part is the one that will work for me?

Many thanks.
Last edited by bikes4two on 6 Mar 2019, 9:17pm, edited 1 time in total.
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bikes4two
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Re: Headset cartridge Bearing-Shimano BC1-help please

Postby bikes4two » 3 Mar 2019, 10:34pm

gregoryoftours wrote:I take it that is one of the old threaded headsets in 1" variety?
yes

If you can't find the same headset or suitable replacement bearings there are plenty of decent quality ISO 1" threaded headsets around. You will have to watch out for stack height though as of 105s are quite short. If it's only the bottom half of the headset that needs replacing then any 1" ISO standard headset will do, threaded or threadless, just use the bottom bearing, cup and crown race.


That's a good way forward - thank you.
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Re: Headset cartridge Bearing-Shimano BC1-help please

Postby Brucey » 4 Mar 2019, 12:41pm

FWIW I think you can dismantle these cartridges and fit them with new balls, and also that yes you ought to use the less worn one in the lower race. Good grease and good adjustment often make headsets that are less than perfect quite acceptable to ride on, and I speak as someone who can't abide any form of notchiness in a headset bearing.

cheers
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Re: Headset cartridge Bearing-Shimano BC1-help please

Postby Gattonero » 23 Mar 2019, 1:20pm

bikes4two wrote:The lower cartridge bearing in my 1989 Dawes Galaxy has suffered water ingress and requires replacing but I am unable to find anything on the web when I search for "Shimano Cartridge Bearing BC1" or similar phrases.

There may be alternatives of course, but I do not know how such bearings are described. I have meaured the internal and external dimensions and the overall thickness, but I do not know what the angle of the bearing tapers are.

The cap covering the bearing cups says Shimano 105 if that helps?

"Shimano Cartridge Type Bearing BC1"
Internal diameter - 27mm/ 1.063"
External diameter - 41.7mm/1.642"
Thickness - 7.7mm/0.303"

Can these bearing be split and just the balls replaced? At a push I could put the top bearing on the bottom cups and re-grease the damaged one, but it is a bit rough at the moment.

All assistance/advice/information gratefully received - thank you.


That is a "semi-cartridge" type of bearing that was used by may Shimano headsets, IIRC from the 105/Deore level above.
You can open the cartridge with a thin flat tool (i.e. an old kitchen spreading knife that's been ground off) and replace the balls (1/8", if I'm not wrong) and give a light ground to the races with a small emery wheel for the Dremel.
Depending on the severity of the damage, it may work reasonably well, though it won't be back as per new.
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Re: Headset cartridge Bearing-Shimano BC1-help please

Postby Brucey » 23 Mar 2019, 3:47pm

Gattonero wrote:…..replace the balls (1/8", if I'm not wrong)....


IIRC they are 5/32" balls inside?

e.g.

https://si.shimano.com/pdfs/ev/EV-HP-7410-1379A.pdf

cheers
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