Playing with disconnectors

[JRhodes]

We are machining a new angle on our disco's.  Have a bunch to do, but the difference is profound.  We took a slicked up CZ and installed one of our disco's and tested the DA.  Using our default 13# hammer spring, the average DA was 7 lbs. 12 oz. 

We took the disco out, added a 3 degree angle to the face and the pull weight dropped to 6 lbs. 13 oz.  The angle also changes the final break away on the DA pull making it the most linear we have ever seen.

We then followed up with 6 more builds and the spread measured from a high of 7 lbs. 2 oz. to a low of 6 lbs. 12 oz.   

We are going to test the P-07/09 discos later this week to verify improvement (or not).

Is this something that can be done on existing discos?  I have a dozen already installed. 


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[Tok36]

A small adjustment for a significant reward. Interesting stuff.

[slikshoes]

What is the projected ETA on release for this new disco, @schmeky;?  Are you willing to share how long you guys target a QA cycle to last?

[SlvrDragon50]

Oh man, I cannot wait. I need all the help I can get on my DA pull haha.

[copemech]

We are machining a new angle on our disco's.  Have a bunch to do, but the difference is profound.  We took a slicked up CZ and installed one of our disco's and tested the DA.  Using our default 13# hammer spring, the average DA was 7 lbs. 12 oz. 

We took the disco out, added a 3 degree angle to the face and the pull weight dropped to 6 lbs. 13 oz.  The angle also changes the final break away on the DA pull making it the most linear we have ever seen.

We then followed up with 6 more builds and the spread measured from a high of 7 lbs. 2 oz. to a low of 6 lbs. 12 oz.   

We are going to test the P-07/09 discos later this week to verify improvement (or not).

Just when I was about to order a disco for new shadow. Post a pic or I will have to call and wear you out on the phone for an hour!

I figure you must be angling these toward the front of the gun, but would that niot tend to wear the top edge of the trigger bar?

[schmeky]

but would that niot tend to wear the top edge of the trigger bar

Trigger bar and disco are heat treated.  Besides the vertical disco "face" is very short where the 3 degrees was created.  Only talking about a .002" slope.  Hard to believe what a few thousands can do.

[SoCal]

I will volunteer to test the disconnector for you.

[Scarlett Pistol]

We are machining a new angle on our disco's.  Have a bunch to do, but the difference is profound.  We took a slicked up CZ and installed one of our disco's and tested the DA.  Using our default 13# hammer spring, the average DA was 7 lbs. 12 oz. 

We took the disco out, added a 3 degree angle to the face and the pull weight dropped to 6 lbs. 13 oz.  The angle also changes the final break away on the DA pull making it the most linear we have ever seen.

We then followed up with 6 more builds and the spread measured from a high of 7 lbs. 2 oz. to a low of 6 lbs. 12 oz.   

We are going to test the P-07/09 discos later this week to verify improvement (or not).

Could you verify the direction of the angle? What SP01Shadow makes sense but I want to make sure this is what you guys have done. Thanks for being willing to share!

[schmeky]

The disco can pivot slightly in its vertical plane, remember the disco is kept in alignment by the frames lower shelf (bottom of the disco) and the sear cages lower bear surface area (top of the disco).  In a perfect world there would be no vertical dispersion of the disco. 

From looking at the discos engagement face after modification, it appears the difference we remove is keeping the trigger bar and disco face perpendicular to each other and thus compensating for the lack of correct initial alignment.  If the disco pivots on it's plane even slightly (and it has to), then the engagement surfaces are no longer parallel to each other.  This will create a high spot at the trigger bar/disco interface.

Cutting the disco to compensate for the mis-alignment distributes the load over a wider bearing surface area, thus making the DA more linear and smoother.   The opposite is what's been occurring, i.e. a smaller engagement surface can create more drag and increase the DA pull.

I feel all we have done is compensate for the lack of proper alignment.

[Tok36]

I feel all we have done is compensate for the lack of proper alignment.

Do you believe that all 75 variant pistols suffer from this misalignment or is it possible that it is the product of redesigns over the years? To your knowledge do the Pre B's or older CZs differ in this regard?

Do you use a cutaway frame in the shop to more visibly study the trigger bar disco interaction throughout its travel? Not being able to observe the disco while it moves has been a significant impediment to my full understanding of it. Even now it holds some mystery for me in its angles during different points of travel. I the past i have pondered building a transparent rig to hold all the parts but now that i think about it a cut away frame might be adequate.

Regardless, it is very cool that you figured this out, thank you for sharing it with us.

[SPO1SHADOW]

The disco can pivot slightly in its vertical plane, remember the disco is kept in alignment by the frames lower shelf (bottom of the disco) and the sear cages lower bear surface area (top of the disco).  In a perfect world there would be no vertical dispersion of the disco. 

From looking at the discos engagement face after modification, it appears the difference we remove is keeping the trigger bar and disco face perpendicular to each other and thus compensating for the lack of correct initial alignment.  If the disco pivots on it's plane even slightly (and it has to), then the engagement surfaces are no longer parallel to each other.  This will create a high spot at the trigger bar/disco interface.

Cutting the disco to compensate for the mis-alignment distributes the load over a wider bearing surface area, thus making the DA more linear and smoother.   The opposite is what's been occurring, i.e. a smaller engagement surface can create more drag and increase the DA pull.

I feel all we have done is compensate for the lack of proper alignment.

Does this also allow the disco to flow smoother between the upper and lower barriers? It seems as though in some guns the double action effort increases after a fitted disco as if the disconnector is binding between the sear cage and the lower shelf.

[schmeky]

as if the disconnector is binding between the sear cage and the lower shelf

That should not be difficult to determine.  I would remove the hammer spring and make a .002" shim out of brass shim stock.  Bend the shim at a 90 degree angle and slip it between the top of the disco and bottom of the sear cage, or the bottom of the disco and the frame.

Slowly pull the DA and make certain the shim will not bind during the full stroke.  If so, clearance the top or bottom of the disco.

[Indy_Tim]

This is pretty cool stuff.  I've had my hands in the knickers of a CZ 75 quite a few times, yet the disconnector has always been a kind of black magic that I've not messed too much with.  I recently picked up an SP01 Compact and will hold off on doing any upgrades until this work of yours follows to fruition.  I'm really hoping to be able to benefit from your work in this area Schmecky     I sure have benefited from it in the past.

[Don1968]

We are machining a new angle on our disco's.  Have a bunch to do, but the difference is profound.  We took a slicked up CZ and installed one of our disco's and tested the DA.  Using our default 13# hammer spring, the average DA was 7 lbs. 12 oz. 

We took the disco out, added a 3 degree angle to the face and the pull weight dropped to 6 lbs. 13 oz.  The angle also changes the final break away on the DA pull making it the most linear we have ever seen.

We then followed up with 6 more builds and the spread measured from a high of 7 lbs. 2 oz. to a low of 6 lbs. 12 oz.   

We are going to test the P-07/09 discos later this week to verify improvement (or not).

Ok, so are you talking about a completely stock 75 other than the discounter and 13# spring?
I ask because while 6#13oz is a large improvement over stock, the DA in my sp-01 is at 4.5#.


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[schmeky]

Don,

My prior post indicated with tested with a 13# hammer spring.  We did before and after trigger pulls to verify.  We then backed this up with a several shop projects.