BFG 158 Balance complete with finger?

[Barnaby]

I want to replace the balance complete on a BFG 158 because the hairspring is distorted. Cousins has a choice of four:

Balance Complete, Brass Finger, BFG 58 794

Balance Complete, Jewelled Roller, BFG 58 793

Balance Complete, Pin Lever, Shockproof (793.1), BFG 58

Balance Complete, Pin Lever, Shockproof With Finger (794.1), BFG 58

 

The one on there now is not shockproof, but I've got a spare BFG 158 balance cock with shock spring, so I'm assuming I can just swap that in and get one of the latter two choices. The problem is, I don't know what a finger is.  Can anybody help?

 

 

[noirrac1j]

11 minutes ago, Barnaby said:

I want to replace the balance complete on a BFG 158 because the hairspring is distorted. Cousins has a choice of four:

Balance Complete, Brass Finger, BFG 58 794

Balance Complete, Jewelled Roller, BFG 58 793

Balance Complete, Pin Lever, Shockproof (793.1), BFG 58

Balance Complete, Pin Lever, Shockproof With Finger (794.1), BFG 58

 

The one on there now is not shockproof, but I've got a spare BFG 158 balance cock with shock spring, so I'm assuming I can just swap that in and get one of the latter two choices. The problem is, I don't know what a finger is.  Can anybody help?

 

 

 

[noirrac1j]

The balance with brass finger means the impulse "jewel" isn't a jewel but a smal metal protuberance that makes contact with the pallet fork. BFG made  1-jewel and 17 jewel varieties of the 158, and both manual and auto. If yours is a one-jewel, then get the balance with brass finger.You can swap out the hairsprings no problem, but if you try to swap the whole balance for the other, you'll also have to swap out out the pallet fork as well.  Otherwise it will hang up  and not run right. You cannot swap out a balance intended for a manual BFG 158 to an automatic because it will sti too low.

J

[Barnaby]

Thanks, that's very helpful.

The movement I'm trying to fix is a hand-wind 17 jewel 158. It is not shockproof. I also have some spare parts from an automatic shockproof 158 (everything except a good hairspring). I would really like to "upgrade" to shockproof, mainly because with non- shockproof I have to totally dismantle the balance assembly to get to the cap jewel for cleaning and lubrication, and the stud doesn't have a screw. (That's how the hairspring got distorted in the first place).

So, can I get the Balance Complete, Pin Lever, Shockproof (793.1), BFG 58 , use the spare balance cock from the auto 158, and the pallets from the auto 158, and they will fit and work?

 

[watchweasol]

Hi Barnaby   Can you post some pictures it might help clarify the position  and elicit further information .

[noirrac1j]

7 hours ago, Barnaby said:

Thanks, that's very helpful.

The movement I'm trying to fix is a hand-wind 17 jewel 158. It is not shockproof. I also have some spare parts from an automatic shockproof 158 (everything except a good hairspring). I would really like to "upgrade" to shockproof, mainly because with non- shockproof I have to totally dismantle the balance assembly to get to the cap jewel for cleaning and lubrication, and the stud doesn't have a screw. (That's how the hairspring got distorted in the first place).

So, can I get the Balance Complete, Pin Lever, Shockproof (793.1), BFG 58 , use the spare balance cock from the auto 158, and the pallets from the auto 158, and they will fit and work?

 

I don't think so. The balance cock of the auto is considerably taller to clear the auto winding mechanism. Take a look at the manual:

and automatic:

It may be hard to see, but the balance cock is taller on automatic, necessitated by the automatic works bridge and one of the reversing gears.

J

Edited May 1, 2019 by noirrac1j

[Barnaby]

Yes, of course, that makes sense!