Front wheel hub. Distance Piece Bearing Spacer too long?

Hi:

I have run into an issue with the front wheel hub on my 1974 MkII, (disk brake) 850 Norton Commando. I'm wondering if anyone else has experienced a similar problem?

I recently had my front wheel hub professionally re-laced with a new rim and wheel bearings replaced. Upon receiving it back, I was dismayed to find that the wheel did not turn smoothly. Upon disassembly, it appears that with the wheel bearings properly home, they foul the central distance piece bearing spacer. In other words it appears the central distance piece bearing spacer is too long - by about 1/8"! I purchased another central distance piece bearing spacer to check length and it is the same length as the one previously installed. I am not keen on any setup where the bearings are not properly home / could perhaps move . I have not seen any mention of some kind of bearing seat shim? Maybe someone dug the seats, or a seat, too deep at the factory? I may try putting one of central distance piece bearing spacers in a lathe and shortening it a bit.

Does my diatribe sound familiar to anyone? Or as my mother would say, am I just "special"?

Cheers,

James

Britstuff said:

Upon disassembly, it appears that with the wheel bearings properly home, they foul the central distance piece bearing spacer. In other words it appears the central distance piece bearing spacer is too long - by about 1/8"!

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Both bearing inner races should be in contact with the bearing spacer.

Britstuff said:

I am not keen on any setup where the bearings are not properly home / could perhaps move .

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"Home" meaning the outer races or inner races?

Britstuff said:

I have not seen any mention of some kind of bearing seat shim?

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There wouldn't normally be one as both inner races locate against the spacer tube.

Britstuff said:

Maybe someone dug the seats, or a seat, too deep at the factory?

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Only one bearing locates against the hub shoulder, the other bearing should locate against the bearing spacer.

Britstuff said:

I may try putting one of central distance piece bearing spacers in a lathe and shortening it a bit.

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I suggest you wait until the actual problem can be identified.
For instance, is the disc-side double-row bearing the standard 4203 (16mm wide) or 5203 (17.5mm)?

Hi L.A.B

Thank you for your comments:

LAB: Both bearing inner races should be in contact with the bearing spacer.

Yes, understood.

LAB: "Home" meaning the outer races or inner races?

Inner races.

LAB: There wouldn't normally be one as both inner races locate against the spacer tube.
LAB: Only one bearing locates against the hub shoulder, the other bearing should locate against the bearing spacer.

Interesting...... I assumed that both bearings inner races should locate against the hub shoulders. It sounds bizarre to me, but I am a newbie when it comes to Nortons. It is tremendously helpful to hear from an expert that that is how is is supposed to be.

Thank you very much for explaining my mistake!

LAB: I suggest you wait until the actual problem can be identified.

Yes, based upon what you say I will wait..

LAB: For instance, is the disc-side double-row bearing the standard 4203 (16mm wide) or 5203 (17.5mm)?

I think I have the bearings (two different) sizes installed correctly. I used the Andover Norton website diagrams for reference. I believe the bearings are the correct size but will certainly double check.

Thank again!

Kind Regards,

James

Britstuff said:

Interesting...... I assumed that both bearings inner races should locate against the hub shoulders. It sounds bizarre to me, but I am a newbie when it comes to Nortons. It is tremendously helpful to hear from an expert that that is how is is supposed to be.

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It is, however, normal for British motorcycle wheels to have only one hub location bearing which in this instance, is the single-row bearing on the non-disc side.
This bearing must be fitted first and the lockring fully tightened (as it's the hub location) before fitting the spacer tube and disc-side bearing. The disc side bearing is then fitted down to the bearing spacer tube, not the hub shoulder.

Therefore, the procedure in the factory manual from section H9. 6-10, drum (and disc) wheel bearing overhaul must be used when installing the bearings.

Got it!

Thank you very much!

I recall an old British tech article on fitting wheel bearings and pointing out an issue with the then currently available double row bearing fitment. Some machining of hub or spacer? Was needed. Had me worried b/c I was about to my front bearings but later learned there is a newer double row bearing that fits without mods and I had that one already.

EDIT:
Here is the OB tech article found in the Technical Information section on this sight:

Tornado said:

I recall an old British tech article on fitting wheel bearings and pointing out an issue with the then currently available double row bearing fitment. Some machining of hub or spacer? Was needed. Had me worried b/c I was about to my front bearings but later learned there is a newer double row bearing that fits without mods and I had that one already.

EDIT:
Here is the OB tech article found in the Technical Information section on this sight:

Old Britts, Wheel Bearing Upgrade Instructions

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Those instructions should be ignored/deleted/burned. The correct bearing 4203 with and without seals are available and no machining is needed. They were hard/impossible to find in the US/Canada for a good while so Fred found a way to machine and use a wider one. 4203-2RS are readily available from 123bearings in France and Don Pender has them too. I normally stock them and have used/sold 44 of them but I'm out now. You can get them in -2RS and -ZZ from Amazon but they are pretty expensive for a Chinese brand.

marshg246 said:

Those instructions should be ignored/deleted/burned. The correct bearing 4203 with and without seals are available and no machining is needed. They were hard/impossible to find in the US/Canada for a good while so Fred found a way to machine and use a wider one. 4203-2RS are readily available from 123bearings in France and Don Pender has them too. I normally stock them and have used/sold 44 of them but I'm out now. You can get them in -2RS and -ZZ from Amazon but they are pretty expensive for a Chinese brand.

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Understood but I'm thinking maybe the OP has got the old sized bearing in his hub and machiningnot done.

Tornado said:

Understood but I'm thinking maybe the OP has got the old sized bearing in his hub and machiningnot done.

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Me too.

I’ve not needed to change any hub bearings, but this is very good to know. From what I understand it’s critical to drive in the double row bearing using the inner race, and not the more normal practice of using a suitable socket on the outer race, as that will drive the outer in too far resulting in exactly what @Britstuff has experienced. It’s probably difficult to put right once there is that much tension on the bearings as well.

Presumably it was done this way because of variation in manufacturing tolerances ?

cliffa said:

From what I understand it’s critical to drive in the double row bearing using the inner race, and not the more normal practice of using a suitable socket on the outer race, as that will drive the outer in too far resulting in exactly what @Britstuff has experienced.

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The double-row bearing can be driven in by the outer race (or, preferably with a bearing fitting tool that rests equally against both inner and outer races) as long as it is only driven in far enough to contact the bearing spacer.

If the procedure is not understood then yes, the bearings could potentially become side-loaded if the outer race is driven in too far.
Because it is a double-row bearing I expect it can be driven in by the inner race without the bearing being damaged.

cliffa said:

Presumably it was done this way because of variation in manufacturing tolerances ?

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With one 'fixed' and one 'floating' bearing there's no requirement for a precisely machined shoulder on the 'floating' side in fact some hubs (Triumph disc, etc.) have no shoulder on that side.

Like @cliffa states, I think the double row bearing was driven in too hard, causing it to jam against the distance spacer, rather than just kissing it. Armed with everybody's helpful advice I will have a go at reassembly sometime today.

Cheers,

James

Sorted! Followed @L.A.B directions and now all is well!

It certainly appears as though the double row bearing was driven in too deep, causing it to partially jam against the distance spacer. In my case the bearings were a tight fit, even with the hub being moderately heated. Apparently this was a case of one tap too many when the double row bearing was driven in and not understanding how wheel bearing inner races are positioned on Norton's and, (apparently other) English bikes!

I did NOT modify the distance spacer. All went together very nicely and everything appears to line up.

Thank you everyone!