30 replies to this topic

[smurfomatic]

I've been trying to replace the reverse light switch in the remote change gearbox, since the previous one stopped working. However, when trying to screw the new one in it won't go in far enough - the spring is pushing the switch closed well before it is screwed in.

 

I believe the spring isn't going down far enough into the gearbox, but having removed it (and the plunger) and re-fitted it, the spring still extends too far out. I can't see why anything would be obstructing it, but something must be! Any ideas?

[Spider]

There should ve a lock nut on the switch, though they don't usually come supplied with one. You'll damage the switch if you screw ir in all the way without one.

[dklawson]

????

The Mk1 Mini did not have a reverse light switch on the remote gearbox.  However, the ADO16 (MG-1100, Austin America, etc) did have a reverse light switch that can be used on the Mini.  It replaces the reverse gear detent screw located on the front of the gearbox just below the oil filter.

 

There is no jam nut.  The switch threads into the gearbox and uses sealing washers (with a 5/8" through hole) between the switch body and the gearbox casing.   You need to adjust the number of sealing washer to achieve the correct switch position.  However, I guess if you find a VERY thin jam nut you could use it instead of the stacked washers.

 

The picture below includes as many original part numbers as I was able to find over the years.   

 

 

[smurfomatic]

Thanks all. There is obviously more of an issue, as the spring seems to b catching on something making it next to impossible to screw the switch in more than halfway - and even then the switch is "on".

[The Principal]

edit - the original detent plunger stays in plus the spring with the additional plunger inside the spring, could it be the three pieces are not lined up.

Edited by The Principal, 15 May 2016 - 07:51 PM.

[Spider]

The part number on the locknut is AYB9157. The switch wasn't factory fitted to standard production models here, however, many of the fleet cars had them.

 

The only ones I've found fitted without the locknut have had a smashed in switch.

 

I don't know if the UK had a different switch to us.

Edited by Moke Spider, 15 May 2016 - 09:25 PM.

[smurfomatic]

Thanks Principal, I'll take a look over the weekend and see if I can get everything to line up.

 

Moke Spider - the switch has never had a locknut on it, at least not since I bought it. I tried searching for that part number and can't find it.

[winabbey]

The inside diameter of the spring is greater than the width of the switch 'actuator', meaning the spring sits on the flat section of the switch. It's the steel plunger (22G351) pressing on the actuator that operates the switch. At the other end the spring sits around the extension of the reverse check plunger.

 

1. Are you using the original spring?
2. Have you selected a gear other than reverse when assembling the components?
3. Is the spring sitting around the extension of the reverse check plunger (part 44 in the diagram below)? If you aren't sure, remove the reverse check plunger (magnetic rod, plasticine), fit the spring to the plunger and slide the assembly back into the aperture.

This parts book diagram is of the standard assembly without a reverse light switch. For the latter, a flat copper washer replaces washer #47 and the switch replaces plug #46.

 

 PUB1052 Reverse Check Plunger.jpg   8.97K   36 downloads

 

[smurfomatic]

Winabbey - I think the problem may be that it's in neutral when I'm working on it, rather than in a forward gear. 

 

However, the plunger on the car actually sits completely inside the spring - so something must be wrong there. Can't understand how though, as it's definitely worked in the past before the switch broke!

 

Edit: Sorry, I've got confused between the plungers mentioned in Winabbey's and dklawson's pictures. I will extract the reverse check plunger (just ordered some right angled tweezers which should do the job!) and reassemble. 

Edited by smurfomatic, 17 May 2016 - 09:03 AM.

[smurfomatic]

Refitted everything and the spring seems to still be too far out. This may be because the "new" switch is a different design to the old one. Still works, but the switch is hardly screwed into the block at all.

 

I've ordered a new spring, if necessary I'll cut it down to accommodate the new switch.

[winabbey]

This may be because the "new" switch is a different design to the old one. 

 

Does your new switch look like these?

Attached Files

•  Lucas switch.JPG   15.31K   17 downloads
•  63fd_1_sbl.JPG   14.97K   17 downloads
•  Reverse Light Switch BAU1074A.jpg   22.42K   17 downloads

[smurfomatic]

 

This may be because the "new" switch is a different design to the old one. 

 

Does your new switch look like these?

 

 

No, that's what the old one looks like! The ball o the bottom of the new one is a lot larger, hence why I think the spring needs to be shorter,

[62S]

There are at least a couple of versions of that type of switch. You need a Lucas 34887, Mini Spares have them under part number GAE 131.

[winabbey]

 

 

This may be because the "new" switch is a different design to the old one. 

 

Does your new switch look like these?

 

 

No, that's what the old one looks like! The ball o the bottom of the new one is a lot larger, hence why I think the spring needs to be shorter,

 

But the spring is meant to go around the outside of the "ball", as you call it. The ball presses on the short rod that presses on the plunger. If the ball presses on the spring the switch will be permanently on.

 

I think you need the correct switch. 

[dklawson]

+1 to the two posts above.  The plunger on the switch has to go inside the spring.  That's why I provided all the dimensions for the parts in the sketch I posted.

 

There is a nearly identical switch to the Lucas 34887/GAE131 that you need.  The nearly identical switch has a larger diameter plunger and is routinely used on overdrive transmissions and reverse light circuits on Triumphs.  That switch will not work with the spring you need for the Mini.