7750 Click Spring?

[Brokenwatch]

Hello,

 

Hi Newbie here with my first attempt at watch repair.

 

I just cleaned and disassembled my speedmaster (model 3513.53) 7750 movement having watched the breitling 7750 youtube videos, studied some walkthroughs and also the ETA assembly sheets but am having some problems re-assembling and getting it functioning.

 

I installed all the (new; complete assembly) mainspring, train gear, the bridge, the ratchet wheel and then check by rotating the ratchet wheel whereupon a little a satisfying whirring noise occurs as all the wheels freely spin indicating that they are correctly installed.

 

I install the (new) pallet fork and the bridge for that and it freely moves. Then I install the balance wheel, carefully and several times now but it doesn't enthusiastically oscillate like I see in all the youtube videos the momen it's installed. If I give it a nudge it moves seemingly freely and the pallet fork/escapement wheel moves back and forth but only for half a second then it stops.

 

So I think there's not enough power from the (new; complete assembly) mainspring (same thing happened with the old mainspring)and give it some winds then inevitably the click spring pings out of the ratchet wheel teeth and unwinds the crown/mainspring rapidly (I have now damaged 2 escapement wheels in the process, snapping off their location pins)

 

One time I physically held the click spring against the ratchet wheel so that it couldn't ping out, wound the watch a few times (maybe 10 turns) and got a few seconds of oscillation from the balance wheel but knew that the moment I stopped holding the click spring it would just ping out again!

 

I notice now on ebay someone is actually selling a 7750 movement but with the click spring actually soldered (!) in place presumably to stop it pinging out like mine!

 

I am trying to persevere and repair this watch myself despite this so joined this forum!!! I've tried assembly about 5 times with this now but can't get past it. Any ideas? Thanks.

 

[CKelly]

Hi,

   I have repaired several 7750 movements and have never noticed the problem you are describing. First off let me try to figure out what you are seeing. Does the click spring actually fly off the watch or does it just disengage from the ratchet teeth? If it is disengaging I would almost guess that the ratchet wheel isn't seated properly. The ratchet wheel sits very close to the plate so that the spring should not get lodged under it. I can't remember if there is a counter sunk part in the ratchet wheel for the screw, if so it might be possible the wheel is on upside down. Other than that the spring itself might be bent somehow. Check to see if it is laying close and flat to the plate. If you take and post some close up pictures it might help. I have a bunch of 7750 parts if you should happen to need any.

Charles K

Edited October 11, 2015 by CKelly

[Brokenwatch]

Thanks for the reply Charles. I've ordered a new escapement wheel to replace the one I just broke :/ and I'll reassemble. If I still have problems (fingers crossed I won't) then I'll post a photo or two.

 

Thinking back the barrel did seem a bit more difficult to wind with the crown possibly putting too much tension on the (puny!) click spring which then eventually disengaged with the ratchet teeth by springing out slightly vertically upwards. Its a new click spring which is installed flush to the bridge, fully pushed in.

 

The ratchet wheel is the same both sides though, just a flat piece of pressed metal with a square hole in the middle which slots straight onto the barrel with no countersunk screwhole. Just a plain 902 screw holds it in place. It looks like it can be installed either way up (there's nothing in any guides to say otherwise), teeth are in good condition too, no visible wear.

 

Maybe/probably just me being a noob though! I'll update this week once I've reassembled with the new escapement wheel.

[CKelly]

I just looked through my 7750 parts to check if I had a click spring so I could see up close what another issue might be. The click spring I have is basically a wide v pattern, say bent at about 120 degrees. The ends are roughly the same length from the point of the v. Now I didn't measure them so I'm just guessing. The spring also has a small bend in one of the legs which would raise or lower that leg depending on how it is installed. It could be that the spring itself is installed backwards. You could try taking it out and swapping ends. Since you say the spring disengages toward the upper side of the ratchet wheel it may be angled up when it should be angled down. I don't have a plate to install my spring on but I have gone back and looked at the tech sheets and it appears to be that the plate the spring attaches to is milled so the spring should be lower closer to the ratchet wheel. Since you say it happened with the old mainspring it's possible the click spring was installed improperly by someone earlier.

Charles K

[Watchdog]

Very brave man to take on a 7750 as your first watch repair.. Maybe take some pics? There are some pretty good folks out here. I'm sure one of them could help.

Personality , I think your barrel and mainspring is fine. I'd look else where . Something has to be out of place or in wrong???

[perpetual92]

Did you forcefully remove balance cock when disassembling movement and some how take out of position the roller jewel?

[CKelly]

Hi,

   I have since gone through my parts again and will retract my statement about the click spring could maybe be in reversed. I now see that it can only go one way. I had another spring mixed in with some 7750 parts and didn't see the right spring. Don't ask how I had the wrong spring mixed in or even where it came from as I have no idea.

[Geo]

Don't ask how I had the wrong spring mixed in or even where it came from as I have no idea.

I have a couple mixed in with the house furnishings. :D

[dadistic]

Don't ask how I had the wrong spring mixed in or even where it came from as I have no idea.

It's mine!

 

Flew out of my font 76 movement the other day, must have landed in with your parts.

 

Cheers!