Reverse selector plunger

[GavinL]

Just rebuilding a gearbox with a new extension with reversing light switch, and I've got two versions of the reverse selector plunger.

20201101_193654_crop_73.jpg (262.21 KiB) Viewed 1856 times

Is there any difference between them? Also how far in do most people end up screwing it in? I found if I screw it well in I can't select reverse, albeit with the gearbox on the bench.

[Murrayminor]

The plunger with the elongated detent ball is for the gearstick play.


As seen here:

https://www.moss-europe.co.uk/shop-by-m ... 58-66.html

[GavinL]

The gearstick play plunger 22a84 is a brass tube if you google the part number (108), so it's not that. However, looking at the Moss catalogue in more detail it looks like there are two options for the reverse plunger - 105 (a ball bearing) and 112 in the image? Both parts are listed as BLS110 which is a ball bearing, but the image for the second is definitely different , perhaps because the different plunger is no longer available?

Screenshot_20201102-081038_Samsung Internet~2.jpg (35.82 KiB) Viewed 1818 times

[philthehill]

Looking at the MOSS parts list for the 1275cc Midget gearbox all three plungers (as shown in the above photo) are utilised.
The 948cc/1098cc Minor gearbox only has the two plungers.
The control shafts are different - 1275cc Pt No: 22A475, 948cc/1098cc Pt No 2A3350. The difference in the shafts may make it impossible to select reverse gear with the third plunger fitted fully home.

[GavinL]

Phil I think we may be at cross purposes, as the reverse selector plunger doesn't engage with the control shaft, it engages in a notch in the reverse protection plunger ( 100 in the illustration), providing the positive feel of going through a 'gate' when you move the gear lever across when selecting reverse, before pulling it backwards.

Also the two outer reverse plungers in my photo are identical, the only difference is that one is 'exploded'.

Giving it some more thought, i wonder if the difference in the plungers has anything to do with the different applications to a Midget gearbox extension and the Morris Minor - the midget gear lever is 6 1/2" long, the Minor 11 1/2", so you would need twice the effort to move the Midget lever against the force of the detent provided by the reverse selector plunger in the recess in the reverse protection plunger.

This would also explain why the reverse selector plunger is sometimes 'wired' in position ( not always, the hole for wiring hadn't been drilled out in the Midget extension, nor the bolt), so that the resistance to going through the 'gate' can be adjusted?

[philthehill]

The two outer plungers in your photo above appear to be different. The one on the right is waisted and has no threads directly under the hexagon head. The one on the left does not appear to be waisted and has threads directly under the hexagon head.
According to the MOSS parts web site only the centre plunger in the photo above has the copper washer fitted.
I would use the search facility to try and find additional information as regards changing the remote housings between Midget and Minor and gearboxes.
viewtopic.php?f=4&t=6251&p=54945&hilit= ... ote#p54945

viewtopic.php?f=4&t=68921&hilit=1275cc+ ... ght+switch
There are several more posts regarding the fitment of the 1275cc Midget remote to the Minor gearbox.

[GavinL]

Phil all the plungers are identical, it's just that I've fitted fibre washers to two of them which are hiding the waisted part.

The second thread you reference is mine, when I was trying to adapt a standard extension and add a reversing light switch.

Anyway I'll reassemble the extension with the left hand assembly which should work OK, I don't think it will make any difference which one I fit, I was just curious

[GavinL]

So I've been playing around with them this evening and discovered that the plunger bodies are not identical - the spring recess in the plunger bodies that use the ball bearings are 23mm deep, the bullet shaped plunger body recess is 30mm deep, so that when using the same spring the overall assembled lengths are the same.