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MG TD TF 1500 - TF Ignition Coil

Brought this up on another site. Was the Q-12 Lucas coil on the 55 TF originally painted Black or not painted at all? Also, did it have a Lucas decal or ID plate? I understand that this might be different for Australian cars where some minor changes were made, not sure. PJ
PJ Jennings

Just found this picture of the coil on an unmolested 1955 mgtf 9052, still owned by the original owner. It looks like it has, according to the decal, a Lucas LA-12 coil. I thought the QA-12 was original but this photo says I'm wrong. Look at the pic and give your impression. PJ


PJ Jennings

Paul,

Lucas Q12 coils were used on T-ABCDFs until November or December 1954. Painted black case, bitumen solid filled coil. Taller and smaller diameter than the LA12 coil used in later TFs. A raised "Lucas" was stamped on the body. I haven't seen one with a Lucas decal.

LA12 coils replaced Q12 coils sometime after TF7973 between late November 1954 and early January 1955. Natural aluminum case, oil filled coil. Shorter, fatter, and usually hotter to the touch than Q12 coil. "Q12" decal as on TF9052.

Lonnie
TF7211
TF681






LM Cook

Lonnie, My TF8353 was built on December 12th, 1954 so it should have an LA-12 coil as the original. Thanks for the date of the QA-12 cutoff, something I wasn't aware of. So, I have a good QA-12 coil on the car that will be eventually replaced. Thanks again for the info. PJ
PJ Jennings

I pulled an LA-12 from an original TF. Other than that I have no idea what else they used. As far as Q-12 goes, I believe they were all black.
Steve Simmons

Error re: decal on coil -

The last sentence in the last paragraph should say “LA12” decal as on TF9052.

Lonnie
TF7211
TF682
LM Cook

One thing I noted is the different hold down clamps. The earlier Q-12 had a straight uniform shape. The LA-12 has a dog-eared hold down clamp. Unless those were changed along with the coil, that might be a clue as to what your TF originally came with. To add a little confusion, my TF1500 was built 8/13/1954 (7022/XPEG852) As you can see from the pictures, it has the LA-12 coil, silver but the label is missing. The date code stamped on the bottom is 8-54, which pre-dates 7973, and has the dog-eared hold down clamp.






Jim Rice

I'm as confused as you about the "official" date that the TF coil was changed from Q-12 to LA-12. I found the data for my post in a number of MG manuals and parts lists.

No changeover dates are shown in any of the documents. I estimated the changeover date from conversations with other TF owners whose TF had one of the two coils when new.

Jim - your coil has all of the numbers listed in the manuals, but a build date earlier than some other TF owners with Q-12 coils. I'm trying to decide which coil to put on my TF7211, XPEG977 restoration (23-Sep-1954). Thought it was Q-12 until I read your post. I guess that either is "correct." Gotta change my Coil document.

You are right about the hold down clamps. I checked the clamps on the Q-12 coil in my wife's TF681. It has the clamps that you described.

If the spread of dates was only a few days for TFs with Q-12 and LA-12s, then I would assume that coils were thrown into a box and workers attached the first one that they grabbed. Date spread is too large.

If you really want to get confused, then see the appropriate pages in the TF WSM, Lucas Parts List, Early TF Parts List, Late TF Parts List at the end of this coil document on my Google Drive!
https://drive.google.com/file/d/1vj_i5m6PnKVLKk_RmdTpaxUwscpu5YMn/view?usp=sharing

Lonnie
TF7211
TF681
LM Cook

Lonnie:

Maybe the engineers in Abingdon initiated the change on a TSO on a certain date, but I imagine management and production were not going to throw out perfectly good Q-12 coils! Likely as you surmise the various lots were comingled and installed, as randomly pulled from the coil bin, until the Q-12's were no more. I recall many years ago similar discussions about when other part changes were introduced. I don't recall those ever being confirmed. Another example is the difference in our cars. Yours (7211) was built 189 vehicles after mine (7022). Yet, your engine (977) was only 125 engines behind mine (852). If things had flowed as we may have thought, you should actually have engine 1041.

I guess either coil could be correct for you car. I think I'd use the clamp as a guide.

Jim
Jim Rice

Well, seeing just how large a gap between the Q-12 and the LA-12 changeover and knowing my 8353 TF came to me with the Q-12 coil after being in a doctor's garage for over 20 years it's questionable. The car was bought new in California in January 1955, sold to the doctor around 1956, and wrecked in the early 60s by his brother, moved to Alabama when the doctor retired along with his other British cars. I don't think the coil was ever changed from the factory, the paint under the bracket and other things indicate such. So, I'm leaving the Q-12 coil in place as it is now, future generations can argue the point! Grin. PJ
PJ Jennings

My March 1955 TF came with a Q12 coil when I bought it in 1970. Many years later I looked at the stamping on the bottom and it said 9 48.

And I thought that the hold down clamps came already tacked to the coil, so wouldn’t be a good guide as to what was there originally.

David
David Wardell

David:

When you say "tacked" do you mean a spot weld or soldered together? I've removed my coil on a number of occasions, and saw no evidence of any tacking. My coil is retained in the dog-eared bracket by tightening a long screw on the underside of the bracket, then the coil and bracket assembly is bolted to the firewall. Mine is a LA-12...but maybe the Q-12 was in fact tacked to the bracket?

Jim
Jim Rice

Jim, I do mean soldered or spot welded. My 1948 Q12 coil was like that. I have seen Lucas coils fastened in the way you describe, but not many.

David
David Wardell

The LA-12 coil I have in the box has the so-called dog-eared bracket as illustrated in an earlier picture, it's in excellent condition, much nicer than the Q-12 coil I have, and has a Lucas label on it, the Q-12 I have has no label.
PJ Jennings

The date on my LA-12 is 11-54. Car was built in mid-December 54. ???
PJ Jennings

PJ:

The dates of the LA 12 coil and your car align pretty well...similar to mine. That said, if your car came with the Q12, doing a swap for the LA 12 wouldn't raise any eyebrows. At this point it's a preference call. Given the Q 12 is what....68 years old, it could last years or decades more before failing and then needing to be replaced with the LA 12, which is just as old. Out of curiosity, was the LA 12 a recent purchase? Used or NOS?

Jim
Jim Rice

Jim, the LA-12 coil came to me by chance a few years ago. Bought it from a fellow who had a few TF parts he wanted to get rid of, I bought the whole bunch. Strange as it might sound, at the time I wanted the coil just for the scalloped bracket but found out later it was dated. I'm sure it's used, even though it looks perfect with no scratches or dents. PJ
PJ Jennings

PJ. My recent acquisition of TF-8200 “1500 XPEG” has a LA-12 coil having a date code of 11-54 which coincides with the car’s build date.
W A Chasser

Bill, if your car is TF8200 then my car TF8353 it really makes sense that my car must have originally come with an LA-12 coil. Very possible that when my car was put back together after being completely torn apart and set over 20 + years in a pile, the original coil could have gotten lost and the Q-12 put on as one was handy. I think I'll leave it alone for now, it runs beautifully so why change anything? PJ
PJ Jennings

This thread was discussed between 29/07/2022 and 19/08/2022

MG TD TF 1500 index

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