gearbox bearing shims

[kevin s]

I'm in the process of re-building a 1098 gearbox,

I have one thing I'm not sure about which won't be covered by the manual. The bearings are now supplied with a shim because the original had a slightly thicker hub, the guide from the Dorset group clearly shows where this goes on the 3rd motion shaft which makes perfect sense, my question is should there be one on the first motion shaft?
On disassembly it had a shim on the front of the first motion shaft which I can't see serves any purpose (the gearbox has been re-built in the past), should there though be one on the back of the bearing effectively placing the shaft further in the box?

[philthehill]

If I have read this right -the shim you refer to fits between the bearing outer race and the gearbox front cover.
The shims are supplied in 0.004", 0.006" and 0.010" sizes. The shim or shims hold the outer bearing race in place eliminating any fore and aft movement of the race.
The shim is item No: 40 in the link below.
https://www.moss-europe.co.uk/shop-by-m ... 51-71.html
The depth of the bearing outer race entering into the gearbox casing is limited by the circlip which fits around the outside of the bearing outer race.

[kevin s]

I should have made myself clearer, this is shim that goes on the shaft before the bearing, I will need to measure the outer ones you mention but can't really do that until I have the bearings and it's all assembled.

[philthehill]

The shim you refer to is a plain washer (item No: 41 in the above link). The washer is there because the lock tab (No: 42 in the above link) is not strong enough or suitable to retain the bearing. Therefore the washer must be in place.

[kevin s]

Thanks, its very thin for a washer!

[philthehill]

So that we are both speaking from the same hymn sheet so to speak - a photo of the said washer both fitted and stand alone would be appreciated.
Phil

[paul 300358]

I assume that you have read this from the Dorset branch? https://www.dorsetmmoc.co.uk/wordpress/ ... ebuild.pdf If so, are you referring to the shims at figure 5? If so the shims are there to take up any play due to the tolerance from the machining of the front and rear cover. They are also available from Mirabelle classics.

[philthehill]

Paul - I presume that your question is directed at kevin s.
There does seem to be some confusion as to what washer/shim is being referred to and where it is fitted. That is why I asked for one or more photos of the washer/shim in question.
Reference the washer I referred to in my post above:-
Page 12 of the Dorset link above does not mention or show the washer BMC Pt No: 6K559. It is shown in the BMC parts list as sitting between the lock washer BMC Pt No: 2A3035 and the first motion shaft bearing BMC Pt No: 2A3245.
There is no comment in the BMC parts list AKD559 remarks or change point column of the washer BMC Pt No: 6K559 being deleted.
I would advise that the washer BMC Pt No: 6K559 is fitted.
If the bearing was able to turn/move; the lock washer would soon be damaged and become non effective allowing the first motion shaft nut BMC Pt No: 2K6677 to become undone.
BMC/BL may have decided to delete the washer at a later date but I have no information as to them doing so. Any additional information would be gratefully received.

[paul 300358]

Sorry I should have read the thread properly, Kevin has already stated he has read the Dorset guide and philthehill has already answered the shim question!!

[kevin s]

This is the one (pic taken from Dorset document)

Screenshot_20230204_201347_Samsung Notes.jpg (230.08 KiB) Viewed 1441 times

I understand why you need the one behind the tab washer, it will allow the bearing to move ( far from ideal but you do get micro movement in such joints) without imparting a rotational force on the tab washer.

[philthehill]

This is even more confusing as you say in your original post that the shim/washer is question was found on the first motion shaft now you show a photo of the 3rd motion shaft with a shim from page 4 of the Dorset rebuild manual !!

[taupe]

May just add to the confusion but from what I remember .....correct length bearings being unavailable new some suppliers provide a narrower bearing and a thin spacer to make up the difference?

Maybe it was this one on ESM .site.....'third motion bearing 3rd Motion Shaft Bearing (22A465) *** TOP QUALITY KSM BEARING *** Supplied with the required spacer for the 1098cc gearbox application.'

Taupe

[philthehill]

The third motion shaft bearing is supplied with a spacing shim/washer.
https://www.morrisminorspares.com/gearb ... ng-p830849
The first motion shaft bearing is supplied without any reference to or including a spacing shim/washer.
https://www.morrisminorspares.com/gearb ... ng-p830844

I think that there is confusion as to what constitutes a 1st motion, 2nd motion & 3rd motion shaft in a Morris Minor gearbox.
So please excuse me whilst I teach granny to suck eggs.
The shafts are read from the front - so
1st motion shaft...................Fits into the front of the gearbox and its front end engages with the rear of the crankshaft.
2nd motion shaft..................This is the lay shaft.
3rd motion shaft..................This is the shaft that exits the rear of the gearbox and engages with the front of the propshaft.
Reverse motion shaft............This does as it says and reverses the drive.
Phil

[kevin s]

My question was referring to if a shim was also needed on the first motion shaft, the kit of bearings we are buying has 2 of these shims in it, looks like it doesn't. The bearings I've taken off the first trans measure the same on the 1st and 3rd shaft but don't have the shim behind (I'll measure the second set later), Sounds like originally they were different and hence the shim.

[kevin s]

Just checked the bearings from the second box, these have a thicker bearing inner sleeve(both sides of the bearing) for the back bearing so all is clear now, to get it as per original there should be a shim each side of the bearing so some suppliers supply 2 but in reality the back one doesn't matter as it just brings the speedo gear a few thou forward.

while we are at does anyone know where you can get a magnetic drain plug for the gearbox? I've had them in cars before and it's amazing how much they collect.

[Myrtles Man]

You could always epoxy one of these to your existing drain plug:-

https://www.ebay.co.uk/itm/204082347896 ... BM4qOY-MRh

[kevin s]

i did think about that or even brazing / soldering one in, no idea if you can do this to a magnet with out loosing the magnetism though.

[paul 300358]

If you heat a magnet to its ignition point (cherry red) it will lose all of its magnetism. I would be tempted to silver solder rather than braze as its cooler.

[philthehill]

Mike Nash is the man to speak to re magnetic drain plugs.

[MikeNash]

Kevin, don't use heat on magnets. They don't like it. Just drill the drain plug, clean it with, say, petrol or meths, and when dry araldite in a cheap neodymium rod magnet like this https://www.guysmagnets.com/neodymium-m ... m-rod-p140 I can't find a photo of my g'box magnet at the moment so please first put your finger thro' the drain hole to check you've a clearance to the rotating parts and then choose a shorter magnet if you're a bit tight on room.
Gearboxes have little wear so you won't find much stuck to it UNLESS you accidentally crunch the gears when you might generate a chip which you really won't want to find it's way into the moving bits.
I've found the 5mm dia X 10mm long rods also go well into the engine sump and back axle drain plugs; the latter gets forgotten but unlike the engine and g'box any bits don't stay at the bottom 'cos the axle is always jumping about. And without any filter the magnets are more important.
Filters only collect down to about 30 microns (a micron is a millionth of a metre or a thousandth of a millimetre) and perhaps a bit lower if the filter is dirty but the magnet will collect down to much smaller sizes depending on the magnet's strength and the how close the particle is to it. While we all know iron & steel will stick to them many other metals such aluminium are "paramagnetic" i.e. they're very slightly magnetic but only when in a magnetic field, but it does mean they'll also stick to a magnet if close enough. So fit them everywhere!
Will that do, Phil?
PS Note that magnets can be obtained down to 1mm diameter and so can be fitted to very small drain plugs. I've got 3mm dia rods in my compressors, log splitter, etc which use 6mm bolts as drains.