Afternoon All,

I am currently working on a restoration project and have come across a conundrum in relation to the gearbox and reverse switch which sits at the front of the gearbox just under the oil filter.

From what I can see I have the original large switch which obviously is not working.

I've pulled the switch out and cannot for the life of me see how it works. Can anyone please explain ? I may be that it has previously been put back together incorrectly and parts are missing. Although looking at what I have I cannot understand how the rod activates the switch.

I've seen links on the forum to an aftermarket switch replacement, but moreover I'm interested if 1. I've got all the parts and how these work with the reverse rod selector.

Any help would be appreciated.

Thank you

When reverse gear is selected, the long selector shaft pushes through the case toward the switch. This moves the detent plunger up towards the switch.

Do you get continuity through the switch when you push the button on the inside?

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There is a small diameter pin inside the spring, I can't see if it's there?
Not present if no switch fitted.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Check continuity while the switch is out on the bench. The circuit should be open with the switch as it is now. Push the ball in and the circuit closes. If that's not happening the switch itself is cactus.

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ex-NSW Police 1970 MK II Cooper S
VMCI #43

The small diameter pin fits inside the spring and connects the detent plunger to the ball in the end of the switch to close the circuit. There should be a fibre washer under the switch, too.

Thanks for those who have replied.

I'll check the continuity whilst switch is out. Am I correct in saying that the detent plunger only moves about 2 millimeters ?

yeah, it's not much

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did I tell you that I won a trophy?

I found new switches don't work, they have made the ball plunger too big diameter to clear the spring.
Need to make an adaptor.

Edited for clarity.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Guessworks Mini Gearboxes does one which is supposed to work well.

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Slide
1965 Mini Van (1360)
1970 Mk2 Cooper S (1310)
1978 Rover SD1 V8 (4.6)
1996 Land Rover Discovery V8 (4.0)

Drmini: Are the new switches that you are referring to, that have the bigger ball, also the ones with the M16 metric thread? If so, the metric version is now being sold using the original mini/1100 part number of GAE131 but, as you say, don't fit minis.

If Ramon Maurice needs a new switch, there are some NOS ones for sale on ebay-type places, under the original Lucas p/n of 34887b, which is stamped on the switch body.

@Bill B,
I didn't measure the thread but it did screw into the gearbox fine.
Yes it had the Mini part number GAE131but I think it's off a Jag or something.
I sourced a S/H switch instead.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Problem sorted. Switch was incorrectly fitted by last user. Actually surprised that the switch is still in good working order given that it had 3 coats of paint and is probably 40 years old. Now for the rebuild.

Thanks to all who offered advice.

Ramon