Author Topic: PreB Problem with DA  (Read 569 times)

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Offline briang2ad

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PreB Problem with DA
« on: December 24, 2018, 10:17:03 AM »
Have an old 84 PreB,  NIce gun and is now Gunkoted.  Its been polished up a few times.  This COULD be the source of my problem.  The DA is spanking light - and no spring changes - it is THAT smooth. 

Problem:  In DA, from time to time, I run into a problem (more right handed than left) where the DA pull fails to complete the cycle. I hit a wall and it either doesn't break or it breaks LATE. 

I SUSPECT I polished the trigger bar too much. 

I suspect I can fix this with a new trigger bar but I may have to fit it from a new stock one.  Any thoughts???  Thanks. 

Offline eastman

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Re: PreB Problem with DA
« Reply #1 on: December 24, 2018, 10:10:42 PM »
first thing I would check is the tension on the trigger bar lifter springs. It may be too much pressure or unbalanced
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Offline briang2ad

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Re: PreB Problem with DA
« Reply #2 on: December 25, 2018, 10:19:54 AM »
I suspected this also.  Looks OK - attached in the right places -  not hanging out.  I SUSPECT that all the polishing I did made the engagement LESS with the disco/hammer and it doesn't go back far enough. 

I don't want to jump to conclusions, but I think it MAY need a new trigger bar - will new B model fit the PreB?


An alternative id that I wore down the sear ramps enough that it fails to make enough engagement with the sear lifter and the hammer does not clear the sear in DA. 

(May call CGW this week also).

« Last Edit: December 25, 2018, 10:55:48 AM by briang2ad »

Offline copemech

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Re: PreB Problem with DA
« Reply #3 on: December 25, 2018, 11:34:16 PM »
call CGW to walk you through a tweak on the disco! O0

Offline briang2ad

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Re: PreB Problem with DA
« Reply #4 on: December 26, 2018, 08:57:49 PM »
Talked to David tonight and we discussed a few things including the trigger bar spring and it?s tension.  Read a good thread on the spring here and on the Enos forum and I?ll do the procedure when I get back home.  I?ll check it out and likely call David back. Just afraid all the great polishing I did on the trigger bar years ago changed the DA timing slightly.  But as Davis says, I don?t want to jump to conclusions.
Context:  bought from a buddy in late 80s.  No problems.  About 5000 dry fires and about 500 rods through it.   Detail stripped and polished multiple times, then refinished. After the refinish I noticed the problem, and put it in the safe.  Recently brought it out and it started again (hammer not fully cycling in DA). 

Wonderful felling DA.  Puts s SW revolver to shame.  Original springs except trigger RS and extractor spring.

Thanks.

Offline briang2ad

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Re: PreB Problem with DA
« Reply #5 on: December 28, 2018, 12:36:33 PM »
UPDATE:

Got home and look UNDER the slide with the grips off.  The rigger bar spring hooks are NOT riding in the grooves properly.  The right side rides alsor against the frame and the left not so bad but not in the groove.  What IS happening (I think) is that towards the rear, the trigger bar spring hooks end up slipping and putting uneven tension, so it fails to act in the proper way.  This is what makes it work perfectly some of the time and not others. 

Can I somehow tune the trigger bar spring?  the right side actually seems bent.

I may have produced this having lightly sanded the trigger bar grooves (they had machine marks in them.  They also seem SO small as to not keep the spring in the groove.

IN FACT, I tweaked the tension on the one that is really against the frame and it seemd to fix it UNTIL I inserted a mag.  This caused it to fail multiple times.  I guess the mag pushes on  the TB Spring to make it ride alongside the frame.   

Thanks.
« Last Edit: December 28, 2018, 12:42:01 PM by briang2ad »

Offline eastman

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Re: PreB Problem with DA
« Reply #6 on: December 28, 2018, 09:55:11 PM »
you can manually bend the trigger bar lifter spring  to adjust it.
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Offline briang2ad

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Re: PreB Problem with DA
« Reply #7 on: December 29, 2018, 02:30:09 PM »
Thanks.  I may buy a new one.  Talked to David at CGW yesterday and he thinks this is it.  I will order another couple anyway. 

On my 88 - I detail stripped and installed all.  Then the DA started to malf.  Tightened the spring screw and all is well.  These TB springs can be damaging! 

Offline briang2ad

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Re: PreB Problem with DA
« Reply #8 on: January 05, 2019, 12:01:18 PM »
New trigger bar spring placed in the gun and the problem was SOLVED... for a few minutes.  Then I placed the serial numbered mag I have in the gun, and VOILA - problem in DA re-occurred.  I was crushed.  IN and it didn't break in DA.  Out and it did.  WIERD.  Then I thought, let me tighten the screw HALF a TURN.  And... it is fixed.  It always breaks now in DA.  The DA on this gun is phenom - never touched the mainspring, and it FEELS like 7 LBS and smooth as silk all the way through the pull.

So... the tension on the screw on the spring yoke is CRITICAL.  Do y'all STAKE the screw (like the original PreB) or Loc-Tite it?  Thanks.

Offline M1A4ME

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Re: PreB Problem with DA
« Reply #9 on: January 05, 2019, 01:35:42 PM »
I'm no expert.  I can tell you some things I've observed.

One is, that on some pistols, if you turn the screw down good and tight it twists the spring around and binds it up.  I've tightened the screw down, see the spring pop out from under the trigger bar on one side and twist sideways.  Then I loosened it up just enough for the screw to go back to a balanced (side to side) look and it worked great.

I've had the screw/spring out of a couple of them, maybe three??  I've not loctited or staked it back in.  On one I remember it being tight (as if the notches on the sides of the screw head were still rubbing the metal displaced by the original stake job) as I screwed the screw back in.  On the Pre B CZ85 I just vowed to keep and eye on it every time I cleaned/lubed it and I never noticed it trying to turn loose either.  As they say, your mileage may vary.

I've read, right here, that sometimes a magazine will interfere with the legs of that spring.  Remove the slide, look down in the frame/magazine well and insert a magazine (I'd try several) and see if any of them make contact with one/both of the spring legs.  Just to be sure.

I've seen at least one trigger bar with little to no groove in the bottom to help hold the spring leg in place.  I've read, here again, one or more forum members say they had to cut deeper grooves in one side or the other of a trigger bar to insure the spring stayed in position.  I thought about doing that on mine.  Tried with a small file, to make the groove deeper, gave up after not much progress and then just stoned it some trying to smooth out what little groove there was (must be some hard steel - or I had a sorry file).
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Offline briang2ad

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Re: PreB Problem with DA
« Reply #10 on: January 05, 2019, 03:25:56 PM »
Good responses - thank you sir.

On problem was that I polished the spring where it interfaces.  I don't recommend it.

Another issue may be that I polished the bar undersides a bit and as you say I MAY have to go in and increase the groove.  I read in the smith thread that some take a thin dremel griding wheel and manually and carefully to this. 

I had NO idea that the 75 series could be so finicky around this part.

UPDATE:  Messed up again.  Mag out - OK.  Mag in - no go.  Backed off the screw - OK again.  We will see how long this lasts.

One improvement on the P07/09 series is that they are tougher to screw up in this area. 
« Last Edit: January 05, 2019, 04:21:01 PM by briang2ad »

Offline sberres

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Re: PreB Problem with DA
« Reply #11 on: January 07, 2019, 03:33:00 PM »
  The first time I put one of these together I decided not to restake the lifter spring screw as it seemed to be catching well along the serrations of the screw head and figured I could just make a habit of checking while cleaning. I mean this is for manufacturing posterity, right?  First date at the range with it and trigger starts going erratically dead and after a few more hiccups becomes unresponsive, just sort of skidding out of DA and nothing in SA. Ok, fine, we?ll figure it out at home.
  The screw had backed itself out enough that the trigger bar wasn?t being raised high enough to do anything. This time it got restaked!  I fixed up an old center punch to be a bit sharper but still a bit bigger than a prick punch. It lives by the gun tools now as there seems to be more stuff staked in place than one would think. From sights to even roll pins. Guess they had to use something in the days before loctite.
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Offline briang2ad

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Re: PreB Problem with DA
« Reply #12 on: January 08, 2019, 07:01:41 AM »
Went home last night and oooops, it needed loosening a half turn again.  Now I think it is right - but I will WAIT, confirm on the range, then likely I'll stake it.  Need to confirm its in the right position, so locktite it out.  This one also is pretty smooth on the sides of the head.  It was originally staked. 

If I have further problems, I will disassemble and look at the trigger bar.  May have to either channel the groove or out in a new TB.  The SA is SOOOO good in this gun when it works right.