Dolls Head Bearings

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I am helping a friend with the refurbishment of a dolls head gearbox from a WD Big 4. All 3 bearings need to be replaced. We were surprised to find a double row self aligning bearing on the mainshaft (the one in the outer case). I would have expected to find single row deep groove bearings on both ends of the mainshaft (imperial) and on the drive side of the layshaft (metric). Can anyone confirm that they should all be single row? Any good reason to fit the self aligning bearing to the shaft? Dimensions of the mainshaft bearing are 5/8 x 1-9/16 x 7/16. Suitable single row replacement codes would appear to be LJ5, RLS5, LS7, or RL85 depending on manufacturer.

The WD16H manual lists the…

The WD16H manual lists the bearings by serial number but not by type. I don't know if thus helps.

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I'm pretty sure..

.. the bearings are just single row type. I can't see any reason for self aligning type.

Thanks

David, thanks for the WD parts list, the '37 civilian parts list does not give the bearing codes just Norton part numbers. However, my internet search has so far not produced a result for MT7/6. SKF RLS5 is dimensionally correct, I will probably go with that.

Ian, thanks for confirming my own thoughts on single row for this application.

Cheers

Dolls Head + (Dross response)

Hi Ian.

Hope All is well in the top six Counties.

RGM lists their Dolls head kit with upright.

I have a Dolls head box to restore and once apart, this is the kit I may use.

The numbers may come in handy?

Cheers,

Neil.

GEARBOX OVERHAUL KIT DOLLS HEAD AND UPRIGHT

PART NO

050107U

KIT INCLUDES: 1 X SLEEVE GEAR BEARING 040098 1 X LAYSHAFT BEARING 067710 1 X MAINSHAFT BEARING 040099 2 X SLEEVE GEAR BUSHES 040062 1 X LAYSHAFT 3RD GEAR BUSH 066665 1 X LAYSHAFT 1ST GEAR BUSH 040046 1 X LAYSHAFT SUPPORT BUSH 040146 1 X MAINSHAFT 2ND GEAR BUSH 040048 1 X GEARBOX INNER GASKET A2/303 2 X QUADRANT CORK A2/345 1 X GEAR LEVER/PAWL CARRIER A2/410 1 X GEAR CHANGE PAWL SPRING A2/419 1 X KICKSTART RETURN SPRING A2/367 1 X INSTRUCTIONS

Evolution rather than revolution.

The doll's head bearing sizes continued until the demise of the AMC Commando box in 1976 or so.

Any Norton dealer will be able to supply. If using a bearing supplier, watch out for the internal diameter of the sleeve gear bearing.

RGM get my vote. Very quick…

RGM get my vote. Very quick delivery. And I believe in supporting our suppliers rather than trying elsewhere. On the topic...there has been lots of discussion over the years about issues with "the layshaft bearing"...but it has two. Is the problem with the inner (drive side) or outer? The outer is only a bush. The inner can be a ball or roller I believe. But which is best? I thought the roller is needed because the outer race goes in the shell first. And did it change over the years?

Also...I see RGM list two cork washers for the Quadrant plate. I suspect that's the reason why my 16H dumps so much gearbox oil. Is there some better alternative? Can't we use o rings or x rings to replace the several cork seals?

Hi David . I had a couple…

Hi David . I had a couple of issues changing AMC box bearings . The mainshaft Bearing housing in the inner cover can be a bit too tight and make the bearing feel "notchy" < i had to fit a bearing with a bigger internal clearance. The Layshaft bearing in the back of the case is often replaced with a roller one ,this can result in a bit of excess axial clearance and attempts to closely shim the clearance out can be frustrating , Mr Hemmings did not like the roller bearing.

All good info

Thanks Neil. The RGM overhaul kit looks useful, although we already have a new sleeve gear bearing and the gear bushes don't seem to have much wear (assessed by attempting to rock the gears on the shaft). I don't have access to the kickstart shaft at the moment so layshaft bush condition still unknown.

Richard, could you give me a bit more info on the sleeve gear bearing ID issue? I have measured the new bearing and it seems to be dimensionally identical to the old one. By the way this is Raymond's box, I think you have been in contact with him regarding the Big 4.