MG TD TF 1500 Ignition switch reconditioning BBS discussion at MG-Cars.net

MG TD TF 1500 - Ignition switch reconditioning

Rob, here is a picture of an ig/light switch with a new decal. The only difficulty is the switch needs to be dismantled to get the decal under the switch lever. "From the Frame Up" sells them. Hugh Pite

H.D. Pite

I have done the graphics for that decal. If you want it in a higher resolution let me know. A local printer could do it for you. Regards Declan

D Burns

Anybody have a pointer for a PLC 6 for sale or know where I can get one? The UK seller has agreed to pay for it IF I can find one. Pic of switch attached. What's not visible in the shot is the broken tip of the pointer. Cheers Peter TD 5801

P Hehir

I have no idea where this pic came from but this is what I'd like to avoid! Cheers Peter TD 5801

P Hehir

The following is from Lew. I've added the numbers & the legend on the pic. Hopefully it should now be plain sailing. PLC 6 REASSEMBLY To reassemble the switch first start with the key switch contact “bridge” (1) (also known as the ignition contact ring). Drop those into the recess in the body first, followed by the metal cover (2) and the spring (3). Add the bottom half of the lock barrel (4). Note there is a small brass button on the cylinder (5) and a corresponding hole in the bottom half. Push the brass button to release the barrel (5a) from the bottom half. Now put the bottom half into the key switch assembly (6), making sure the straight sides of the bottom half engages with the corresponding shape in the contact “bridge”. Now put the nut on the thread which should emerge from the back of the switch. It should be snug, but not overly tight. Finally add the hollow lock barrel (5b) (with the two tabs, also known as the Mazak lock body cover) into the two slots in the body. (During disassembly check & ensure that it isn’t broken. Be careful here, as that thing is unbelievably fragile. If the tabs are at all bent over at the back of the switch, do not try to remove it as you will break the tabs off! With one tab broken, you can still use it but if both tabs are broken then the switch is toast!) Note that there is a cut out section which needs to go over the key switch stop (7). Drop the brass contacts (8) into the switch body making sure the contact plate (9) engages with the molded stop in the body. This is what provides the stop for the lighting switch and does not allow it to go too far clockwise or counterclockwise. Follow this by the phenolic insulator disc (10) and the spring (11) with the large spring end first. This should be followed by the face plate (12) with the knob (13) and retainer (14) already attached. The cupped shaped keeper (15) should be fitted with the concave side facing the back of the switch. Now, ensuring you have the 4 projections on the back of the knob lined up with the corresponding 4 “holes” in the contact plate (9) and phenolic plate (10), press the two halves together. Rotate the knob (13) a little to get it to drop into the contact and phenolic plate. Also make sure the lettering on the switch is properly aligned. There is likely only one way the 3 or 4 tabs on the face plate (12) will line up with the notches on the switch body, so get these to align. Now squeeze the two halves of the whole assembly together so the tabs engage with the notches and the face is fully home. When it is properly home, give the face a slight counterclockwise twist so the tabs now rest in the slight detents. The last thing to do is to put the key in the lock barrel (5a) and ease it into the barrel bottom half (4). (Text by Lew Palmer) Cheers Peter TD 5801

P Hehir

Lew. There is no nut, no body. See pic attached. This is how I bought it. The only things I can remove are the spring, insulating ring & the ring that the spring sits in. There is only 3/16" of lock mechanism movement. "Once the lock mechanism is out of the body, you should be able to push down on the tumbler pins to remove the barrel from the lock". Agreed. Problem is I can't get that far. I believe I need the key to remove the lock mechanism as it's not going anywhere... Bob Butson states this in his set of instructions. As this is my first attempt at an ignition switch I'm looking for ways to separate the lock mechanism from the knob without a key. Cheers Peter TD 5801

P Hehir

Just the battle Lew.. yet to win the war! Hi again Lew & other interested parties. Based on my observations on disassembling my PLC6 switch (FA 525), I’ve modified the text that you initially sent & that I'd posted above. There are also a couple of differences with Bob’s PLC2. The sequence & location of the retainer (14) & orientation of the keeper (15) are the major ones. Also my switch, which I’m pretty certain has never been apart (see pics) has no phenolic insulator disc (10) & the position of the small insulator (1b) in Bob’s PLC2 which he suggests sits on top of the small end of the small spring (3) was directly above the thick phenolic insulator (1a ) on my switch, which in turn sat on top of the brass contact bridge (1). The brass button (4a) differs from the one in the dud Moss repro as mine has a small spring (4b) which also protrudes & unfortunately makes your much preferred assembly method impossible. Also I’ve ordered a small pack of brass 6BA hex nuts (10 for $2.90) which should arrive next week enabling me to do away with the solder. The nut can then be permanently secured by using just two nuts. The text & pics follow. You’ll note the ½” copper pipe fitted to (5b) which I used as a form when applying the metal magic in an attempt to reduce the width of the worn window. PLC 6 REASSEMBLY (A) To reassemble the switch first start with the key switch contact bridge assembly (1), also known as the ignition contact ring. This consists of a circular brass bridge & two insulated washers (1a) & (1b). Place this assembly into the recess in the body first, followed by the metal cover (2) with its projections facing the back of the switch, then fit the spring (3). (B) There is a small brass button (4a) protruding from the lower part of the cylinder lock barrel (5) into a corresponding hole in the bottom half of the lock barrel (4). On some switches there is also a protruding spring (4b). Insert the key & depress the brass button (4a) to release the cylinder lock barrel (5) from the bottom half (4).Be careful not to lose the spring(4b)!. Apply a little Vaseline internally to (5), (5a) & (4) as an aid to final assembly & then check that it reassembles easily. Separate both items (4) & (5) again. (If both the spring & the brass button protrude too far thus preventing the use of this assembly method, then disregard the following paragraph (c).) (C) Insert the bottom half (4) into the key switch assembly (6), making sure the straight sides of the lock barrel bottom half (4) engages with the corresponding shape in the switch contact bridge assembly (1) & put the nut on the thread which emerges from the back of the switch. It should be snug, but not overly tight. During disassembly check & ensure that the tabs aren’t broken. Be careful here, as the tabs are unbelievably fragile. If the tabs are at all bent over at the back of the switch, it may be possible to very gently straighten them enough to remove the cover. Great care must be used here! With one tab broken it can still be used but if both tabs are broken then the switch is toast! (D) Position the hollow lock barrel (5b) with the two tabs, also known as the Mazak lock body cover, into the two slots in the body. Note that there is a deep cut out section on the body cover (5b) which needs to go over the key switch stop (7). Place the brass contact plate (8) into the switch body making sure the contact plate cutout (9) engages with the molded stop in the body. This is what provides the stop for the lighting switch and prevents it from going too far clockwise or counterclockwise. Follow this with the phenolic insulator disc (10), if fitted. (E) Assemble the bezel face plate (12), the knob (13) and then the U shaped knob retainer (14). The cupped shaped keeper (15) slips over & secures the retainer (14). Note that the retainer (14) must be fitted first. The keeper (15) will have its convex side facing the back of the switch. The decal must also be applied before (12), (13), (14) & (15) are assembled. Finally fit the circular insulator (10a) and then the large spring (11), with the small spring end first, to the back of the knob. (F) It’s critical to ensure you have the 4 projections on the back of the knob (13) lined up with the corresponding 4 cutouts in the brass contact plate (9) and phenolic plate (10) if fitted. It will be noted these projections & cutouts are different sizes. Now gently press the two halves together. Rotate the knob (13) a little to get it to drop into the contact plate (9) and phenolic insulator disc (10). There is only one way the 3 tabs on the face plate bezel (12) will line up with the 3 notches on the switch body, so check to ensure the lettering on the bezel face plate (12) is properly aligned with the body of the switch. The OFF position should be marked on the switch body prior to disassembly. (G) Now squeeze the two halves of the whole assembly together so the 3 tabs engage with their notches. Ensure the face plate (12) is fully home. While maintaining even pressure give the face a ½” counterclockwise twist so that the three bezel tabs rest in their slight detents. Now put the key in the cylinder lock barrel (5) and ease it into the lock barrel bottom half (4) if it has already been fitted as described in para (c). If not, install the fully assembled cylinder lock barrel (5) & lock barrel bottom half (4) using the key. Check the switch operation mechanically then secure the nut with a dab of solder or preferably use two 6BA brass hex nuts. Refer also to the numbered pic above. Hope this helps those of you who like me were intimidated by this piece of Lucas magic. All that remains now is to actually put it together! 3 Pics to follow. Cheers Peter TD 5801

P Hehir

Pic 2

P Hehir

Pic 3

P Hehir

Pic 4

P Hehir

Pic 5. Shows detail of the contact bridge assembly after removal.

P Hehir

SUCCESS! Ignition switch is now assembled. While looking through my collection of pics, many from this site, I came across some from George Raham which showed his method of disassembly. His pics showed the contents of the switch during removal still attached to the face plate. As I'd tried to use the process outlined in the post above with no success I then came up with my own method. I assembled the face plate including the complete cylinder, large circular insulator & lock body cover. I laid the brass contact bridge, the 2 insulators, the cover piece & the small spring in the body, then placed the large brass contact plate in situ. I compressed the large spring & used two twist ties from a loaf of bread to secure it. The tails poked out of the two slots in the body. After ensuring alignment as suggested by both Lew & Bob I was able to assemble the unit with ease. Once the face plate tabs had been located in their indents I untwisted the two ties & pulled them out with a pair of pliers. Job done! I'm about to recondition the other switch & this time I plan to use the correct MRN cylinder & key, rechrome the bezel & use the decal from AS. Ton's decal works well but a close examination of the U in LUCAS shows it differs slightly from the original. Declan Burns also has artwork for the decal which is spot on. Thanks again to Bob, Lew, Ton & George without whose contributions I'd never have been able to achieve this. Pic attached. Cheers Peter TD 5801

P Hehir

The pic below came from the series supplied by ...

P Hehir

This thread was discussed between 30/07/2014 and 14/01/2023

MG TD TF 1500 index

This thread is from the archive. The Live MG TD TF 1500 BBS is active now.