Longines Mainspring Replacement

[Atticus]

I recently had a 1962 vintage Longines cal 280 men's mechanical watch serviced. The mainspring was "tired" and the watchmaker ordered a replacement from his supplier. Upon receiving it, he noticed the end did not match the one he removed. He nonetheless installed it and advised me that the watch would require winding more often due to the spring slipping if it was tightened too much. The watch runs fine other than the more frequent winding required. I would like to locate an original mainspring if possible. I found on the ranfft website that the cal 280 movement has a mainspring with the dims 1.10 x 12 x 0.13. I assume 1.10 is the spring height and 0.13 the spring thickness, but am not sure if 12 is the spring length in inches or the barrel diameter in mm (the spring does appear to be about 12 inches long, though). On another website I found a diagram showing various spring ends, with one of the figures showing a "Longines T end." It was the only figure that had the word Longines associated with it. My question is: how would one go about locating the correct replacement mainspring for the Longines cal 280 movement? See attached photos which suggests the spring removed does not have a T end, but a thickened bridle (I think that is the correct term, anyway). Thanks from a watch amateur.

[Marc]

I think you'll find that the 12 is the barrel diameter on mm.

 

According to CousinsUK the spring is a GR2673T which is 1.1 x 0.13 x 380 x 12 T end, so 380mm in length. If the spring that came out didn't have a T end then it looks like someone put the wrong spring in in the past.

If it were mine then I wouldn't use it with a spring that could slip as the barrel is not designed for this to happen. I would be concerned that each time it slipped the spring would be shaving the barrel inner wall, damaging it and creating swarf that could further damage the watch.

 

Cousins list the correct part as in stock for £11.95 so replacement with the correct part shouldn't be a problem.

 

By the way, welcome to WRT. Nice Longings.

[clockboy]

Agree with Marc.

 

The correct spring for the Longines 280 is GR2673-T   1.10 Height   0.13 Thickness   380 Length   Dia. 12

 

 

The T  is special Bridle type or T end.

 

 

 

https://www.cousinsuk.com/search?SearchTerm=GR2673-T

[Atticus]

Just checking back in with an update on my Longines. I ordered the mainspring cited by clockboy above from cousins and sent it along with the Longines to the same watchmaker mentioned in my original post. Upon receiving it and looking it over, he said the spring was the same one that he installed in the watch (the one that currently slips if wound more than 12 or so cycles, and holds a wind only for about 14 hours). He returned both. Short of sending the Longines to Switzerland, I am seeking suggestions to solve this curiosity. I know for certain the movement is 280. Could there be more than one mainspring for a 280? Or could cousins be in error? Or the watchmaker?

[Marc]

If you ordered the main spring that CB referenced above (and so long as Cousins correctly supplied what you ordered), then you should have a main spring with a "T" end. The arms of the "T" project through holes in the barrel and barrel lid, anchoring securely in place and making it impossible for the spring to slip.

 

Either Cousins have incorrectly supplied you with a spring that doesn't have a "T" end, or your watchmaker is not looking at the spring properly. It maybe that he has looked at all the dimensions but has not considered the end fitting.

 

I have just checked the parts sheet on Cousins website for the 280 and the barrel definitely has a hole in the barrel lid for a "T" end main spring to fit, so that is the correct end fitting for your barrel.

 

Have a close look at the spring that Cousins have supplied. The outer end of the spring should have a small projection on it perpendicular to the plane of the coil on both sides. These are the arms of the "T" end. If they are not there then Cousins have supplied the wrong part.

Edited February 28, 2016 by Marc

[clockboy]

I have just double checked with my "Generale Resorts" catalogue & it is GR2673-T that is required. It is highly unlikely Cousins & the the GR ref: book are both wrong. If the spring is slipping then it is either fitted incorrectly or there is fault with the barrel. If a T end spring is not being supplied then Cousins have a wrong stock number assigned to the spring.

[Geo]

It's not the first time I have been supplied the wrong type of mainspring from Cousins. :(

[clockboy]

Cousins have vast stock & do occasionally get it wrong last year they supplied me with an incorrect shock Spring but no problems to sort when contacting them

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[Atticus]

Here's a closeup of the spring. It appears to have a T-end, and the model number on the packaging matches. The watchmaker claims that this is the same spring he ordered from his supplier and that which he installed. He did mention that installing it was a challenge--maybe he wasn't able to hook the T into the barrel slots? At this point I would be willing to solicit a second opinion; any suggestions who I might send it to? Seeing that the movement was dissasembled, cleaned and oiled, would asking someone to just check the MS situation be a reasonable request?

[Atticus]

Here's a closeup of the spring. It appears to have a T-end, and the model number on the packaging matches. The watchmaker claims that this is the same spring he ordered from his supplier and that which he installed. He did mention that installing it was a challenge--maybe he wasn't able to hook the T into the barrel slots? At this point I would be willing to solicit a second opinion; any suggestions who I might send it to? Seeing that the movement was dissasembled, cleaned and oiled, would asking someone to just check the MS situation be a reasonable request?

Here's something that puzzles me: I originally sent the watch to be serviced because it was not holding a wind. The watchmaker commented that the spring his supplier provided (which he says is the same one I ordered from cousins--with a T-end) did not match the one he removed. I requested that he return the spring that he removed--see photos of it in my original post. It in fact does not have a T-end, so could have been the reason the watch was not holding a wind (MS slipping). So it may be that my father had the MS replaced at some point, and the person he had do it installed an incorrect MS. However, this doesn't explain why the new MS with a T-end also slips...

[clockboy]

Here's a closeup of the spring. It appears to have a T-end, and the model number on the packaging matches. The watchmaker claims that this is the same spring he ordered from his supplier and that which he installed. He did mention that installing it was a challenge--maybe he wasn't able to hook the T into the barrel slots? At this point I would be willing to solicit a second opinion; any suggestions who I might send it to? Seeing that the movement was dissasembled, cleaned and oiled, would asking someone to just check the MS situation be a reasonable request?

Here's something that puzzles me: I originally sent the watch to be serviced because it was not holding a wind. The watchmaker commented that the spring his supplier provided (which he says is the same one I ordered from cousins--with a T-end) did not match the one he removed. I requested that he return the spring that he removed--see photos of it in my original post. It in fact does not have a T-end, so could have been the reason the watch was not holding a wind (MS slipping). So it may be that my father had the MS replaced at some point, and the person he had do it installed an incorrect MS. However, this doesn't explain why the new MS with a T-end also slips...

Someone of more experience may confirm this but it don,t look like a T end spring more like a TR a hole end spring. Cousins might have have it wrongly cataloged.If correct you will need to contact them.

[Atticus]

Thanks CB. I just sent an inquiry to cousins asking them to please confirm the part number and also advise whether there might be more than one MS for the Longines cal 280 movement. BTW the cousins website is very impressive; I had not saved my invoice, but it was all there on my "dashboard." The only way I could explain my situation, though, was to initiate a return process, which then provides a comment box for additional information. They state a response will be provided within an hour!

[Atticus]

Another bit of info I saw on the net: Longines mainspring barrels were sealed units around the period of this watch (1969). I consulted the graphic that cousins has of the cal 280 movement parts; it does show a sealed barrel (unavailable for general distribution), but it also shows a mainspring separately, suggesting it is possible to replace the spring only. The graphic of the sealed barrel shows that the barrel lid or cap has a small slot that I imagine is there to catch the T-end of the spring. The website where I discovered the existence of a sealed barrel said it is a bit of a chore to pop the lid off a sealed barrel in order to replace the mainspring (the barrel was described as needing to be crimped to re-secure the lid).

When I first considered having this watch serviced, I took it to a local watch repair shop. The watchmaker popped the case back off to inspect the movement and showed it to me. I could have swore I saw the mainspring exposed. I wonder if perhaps the mainspring was replaced at some point and the watchmaker could not re-install the barrel lid, so it was left off. Is this plausible, or would it not function? As I mentioned above, it may also be possible that whoever left the lid off also installed the incorrect spring.

One step at a time: I'll post when I hear back from cousins.

[bobm12]

I've heard that the lid on the mainspring barrel doesn't really do any "job" other than keep dust and stuff away. If the mainspring is correct, the barrel should work without the lid...unless of course the lid in a particular design (I don't know which), doubles as the gear itself...this is the idea/concept exploited in skeleton movements which usually come with the main spring exposed.

[Marc]

I doubt that it would work very well if at all.

One end of the arbor pivots in the barrel lid and the whole assembly keeps the barrel running parallel between the main plate and the barrel bridge.

Without the lid the barrel would flop around all over the place.

[bobm12]

Yeah, I suppose but remember it was all overheard!! :)

 

There might be a solution for skeleton watches that allow this to happen I guess. I don't work on those types of movements so I really don't know the solution.

[clockboy]

The barrel apart from steadying the arbour does little apart stopping contamination of grease/ oil from the spring to the remaining movement. However I did encounter an issue one with a Seiko auto because the barrel lid was scored causing the spring to not wind correctly. I lightly skimmed it on my lathe to overcome this issue.

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