Tuning TX200 Will not cock

[Barkley9]

Hi all. I've tried extensive internet searches, YouTube videos, searching here, taking my TX apart more times than I care to, even emailed Motorhead a couple of times (very appreciative of his responses), but I've reached the point of reaching out for some help. 

Some back story.....I purchased my TX in "FAC" in .22, 2017, shot it for a while, decided to ship it off for tuning to try to get it down as close to 12ft/lbs as possible and try to improve its' overall shot cycle, trigger, etc. It's been running very well over the past few years except for the occasional times the safety won't engage and of course tightening stock screws before shooting. It has the ARH improved cocking shoe and ARH stainless steel fore stock mount piece. 

About two weeks ago, was taking some target shots and all was good until I cocked it and it made a strange sound and I thought it may be ready for a relube. Kept shooting a couple of times, then the safety would't engage/set no matter what I did, then it got to where it wouldn't cock. I will say that I am not a gunsmith nor do I pretend to be one, but I'm fairly mechanically inclined (when I want to be). So began my intense research into this problem and making sure I was well acquainted with the disassembly before I took a tool to my beloved TX.

The aftermarket spring guide had broken and sent some plastic/delrin into the works. Spring looked good as did the smaller top hat.

I cleaned out the compression tube, piston, and trigger block. The nut on the compression tube looked tight as ever. The piston rod looks good as it sits flush in the middle of the piston seal top.

I decided to reinstall the original spring, spring guide, and top hat. After applying the moly I put it all together.

After a few tries it still refused to cock. So, I take it apart, but befire I do I watch "Shootingatdawn" on YouTube and his excellent video of the CD trigger disassembly. I did the same, but before I messed with it I manually cocked it and a couple of delrin shards fell out. I then took apart, cleaned well, relubed, made sure everything moved freely and cocked, and put it back together. I did not adjust the first or second stages of the trigger. 

Put it all back together and wouldn't you know it? It wouldn't cock. Took the trigger assembly back out. Made sure every thing moved freely. 

http://www.airguns.net/general_tx200_trigger.php

This website helped quite a bit. Seemed the middle sear was "grinding" on the bottom sear. So I mollied the poopake out of the bottom sear. I apologize, but I don't have a pointer, but above the trigger blade you can see the trigger pull weight spring below the bottom sear, which I back out a quarter turn, but have since turned back to its original place. 

It seemed to help as I could now manually engage the middle sear by pressing on the top sear. I thought this should be the ticket. Reassembled, confidently went out side, grabbed the cocking handle with gusto, and was quickly disappointed. Didn't cock. So, back to disassembly and reassembly. I've tried using the original top hat, original top hat with spacer, no top hat, tuned delrin top hat, etc. Made sure the original spring guide and washer are properly installed, screws were properly installed, everything was properly lubed, nothing binding, etc. 

I'm unsure of what else to do. Originally, I thought I could just reinstall the original stuff and all would be well. Now I'm thinking maybe some violence took place in the trigger assembly those 2 weeks ago and I'm S.O.L.



TIA



ps, when saying it won't cock I mean it will not engage the sear or more accurately the sears in the trigger assembly

 

[willy]

Man" that is a tuff one" i would put it all back together with out the spring,dont put it in the stock and see whats going on? that frist spring i would heat the top coil up and bend it down,looks like trouble?I have one of the frist TX carbins and once in awhile it wont engage the safety?spray a little liquid wrench in their and come;s back to life"

 

[PeeWeeDaddy]

Leave the top hat out and try it.

I think the top hat is to long..

 

[Barkley9]

Man" that is a tuff one" i would put it all back together with out the spring,dont put it in the stock and see whats going on? that frist spring i would heat the top coil up and bend it down,looks like trouble?I have one of the frist TX carbins and once in awhile it wont engage the safety?spray a little liquid wrench in their and come;s back to life"

Thanks Willy. I appreciate the feedback. The tuned spring and the original spring are the same length. The tuned spring’s ends are somewhat finished, just not to the degree of the original spring ends. I reassembled and tried cocking with action out of stock that’s how I determined that the piston rod isn’t fully seating/engaging the top sear. I’ll be taking it all back apart later today. I’ve got grandkid duty today.

 

[Barkley9]

Leave the top hat out and try it.

I think the top hat is to long..

Thanks PeeWeeDaddy. I thought that too, but tried that and made no difference. Also tried with the delrin top hat as it is much thinner than the stock one, but was still a no go. 

 

[maxtrouble]

What position was the trigger assembly in? Cocked or uncocked? I learned the hard way that the trigger assembly has to be in the cocked position when reassembling a Weihrauch rifle!

 

[JP806TX]

Trouble shooting cocking issue. Trigger versus a spring/piston rod issue.

Testing your trigger

1. Without the spring, take your spring guide and piston and put the assembly seal down on your table (sitting up vertically). Then take your trigger housing assembly and try to push the piston rod into the sear to see if it engages. If there is nothing wrong with your trigger, the piston rod should engage the safety. Then you can lift up the whole unit, click off the safety and the pull the trigger. The Piston rod should release from your trigger unit and drop to your table. If this doesn't work...trouble shoot your trigger assembly. Something in the trigger is not letting the sear catch the piston rod. Try adjusting your trigger/trigger weight until the sear catches the piston rod. Or as suggested look for debris or mis-alignment or other components that are not working properly. 

If Testing the trigger works, then these are your possible issues: A. length of your piston rod too short, B. possible stuff/debris in your piston tube. or C. spring coil bound. When spring is completely compressed...the length of the spring is preventing the piston rod from reaching the trigger sear.

to eliminate C. test with a spring with less coils or a shorter spring (or a spring when coil bound is shorter than the one giving your problem cocking). OR cut a few coils off the problem spring ...if you don't mind losing some speed. Then test to see if the gun cocks. 

To eliminate B. Check the end of your piston tube (where the end of the piston rod screws into your piston) to makes sure there are no washers, top hat, and other debris inside. Shine a bright light down there and do a careful look. I know you said you looked. But do a second look see. I've missed tight fitting black delrin top hats and grease smeared washers before and it's hard to see. 

If you are sure there is nothing in there, you tested with a spring that's shorter (and/or less coil) and the above testing with your trigger/piston rod assembly works. Then you need to slightly lengthen your piston rod assembly. 



Lengthening your piston rod. DO THIS ONLY IF YOU ARE ABSOLUTELY CERTAIN THERE ARE NO WASHERS/TOP HAT OR OTHER DEBRIS IN YOUR PISTON TUBE and you have already ruled out spring coil bound as an issue (and you absolutely want to use the problem spring uncut). 

Take off your piston seal. Scratch a witness mark where the piston rod screws into the piston (note: check to see if the screw tip of the rod is flush with your piston head. If not, you'll need some way to measure this distance so that it's about 1/2 to 1/4 turn less). heat your threaded piston rod area over a stove or a torch. Once there's smoke, unthread the piston rod from the piston. Clean off all the glue from the rod and piston. Then screw in and epoxy your piston rod. Stop about 1/2 to 1/4 turn from the original witness mark.

Good luck.

 

[AirShot]

The spring in the pic appears broken, sounds like you have debris in the trigfer mechanism of up inside the piston. Shards from a broken spring could have caused damage in the trigger mechanism or be stuck up in side the piston... A great suggestion was made to try using the piston stem to cock the trigger manually. If you have packed the trigger with grease that could also cause a problem, flush it all out and just use a light oil. It appears a small issue created a big problem here, stop....thoroughly clean out everything, properly lube and put back together, dont reassemble with damaged parts!! Good luck

 

[Feinwerk]

I once had trouble with my TX200 Mark 3. It had been working just fine and set up in a closet for a couple of months and then when I went to use it it would not cock because the trigger sear would not engage. This turned out to be the original factory grease which had thickened and become sticky in the trigger assembly. I had to clean it and lightly relubricate it with moly paste.

Good to suggestion to also look for chips or other debris in the mechanism. When you have it apart, push on all the levers to make sure they are free and not gunked up by sticky old grease

 

[Barkley9]

Thank you all for your feedback. I got some free time this afternoon and took the TX all the way down.

The tuned spring is not broken, although the spring guide certainly is.....

The original FAC spring looks good..

So I'm not accused of slacking, I took the trigger assembly ALL the way down. Cleaned with brake clean and reassembled with a very light coat of FP10

Some of sears (top and Middle) do not appear to be free of blemishes. But, I'm unsure if that's from the factory or from my recent exploits.

Here is the difference in height of the original top hat and the delrin

The length of the original spring and tuned spring are the same, but the diameter of the tuned spring is slightly smaller...

Thanks jimpoh, I took your advice. Piston rod engages the trigger block outside the action, including engaging the safety.

I put it all together with the delrin top hat, original spring, and original spring guide and with only the slightest use of the moly. 

I tested the compression of the spring, and didn't seem to be binding. I put the stock on and I did have success! It took considerable cocking effort, but it did engage the sears. But, it did not engage the safety. THAT'S PROGRESS! It's still not 100%, but it's progress thanks to yall! 

 

[JP806TX]

If the piston rod is catching on the sear and engaging the safety outside the action.

Then it's not a trigger issue. 

Now you know where to look if you want to ensure the safety engages when you cock (Look at components that are in front of the trigger block: piston rod, piston tube, cocking arm, cocking shoe, top hat...etc ). 

I still think it's debris inside your piston tube. But I could be wrong (that's what my wife tells me all the time).

 

[Barkley9]

If the piston rod is catching on the sear and engaging the safety outside the action.

Then it's not a trigger issue. 

Now you know where to look if you want to ensure the safety engages when you cock (Look at components that are in front of the trigger block: piston rod, piston tube, cocking arm, cocking shoe, top hat...etc ). 

I still think it's debris inside your piston tube. But I could be wrong (that's what my wife tells me all the time).

Thanks for the input jimpoh. I took it apart again. Have gotten really good at taking this beast apart. I made double sure the piston chamber was squeaky clean and nothing was down there except photons. Could only get a "meh" picture...

Here is the piston top and seal. To me, looks good

I broke out the calipers. The stick out of piston rod is about 31mm

Total length is approximately 141mm

The stock bracket and screw looks good and flush

The cocking shoe is an ARH replacement and fits really snug. Barely any play when in its' slot on the compression tube.

The tuned spring and the FAC spring are both 8 and 3/4 inches (222.25mm) long

The tuned spring coil is 3.2mm and the coil of the FAC is 3.4mm

At this point, I'm not messing with the trigger assembly again, its clean and lightly oiled. Leaving everything else apart until I can figure out why it's so difficult to cock and not engaging the safety. I may start throwing parts at it (against my better judgement).

I really appreciate the feedback. Like I said, I've made progress thanks to yall. Any other ideas? Anyone have any quantitative data to add (pictures, numbers/measurements)? I'll keep scouring the internet.

 

[JP806TX]

Gosh darn it... I'm wrong again. 

I better quit while I'm ahead. 

I agree with you. I wouldn't open that gun up again till there are new problems.

good luck. 

 

[bdzjlz]

I have been through this on two TX200s and two ProSports. I guarantee that if you remove 1/2 to 1 full coil off of the spring it will cock smoothly and perfectly.

 

[Barkley9]

Gosh darn it... I'm wrong again. 

I better quit while I'm ahead. 

I agree with you. I wouldn't open that gun up again till there are new problems.

good luck. 

Friend, you chime in any time. Your suggestion helped me narrow this down. 

 

[Barkley9]

I have been through this on two TX200s and two ProSports. I guarantee that if you remove 1/2 to 1 full coil off of the spring it will cock smoothly and perfectly.

I appreciate the idea. I’ll read up on that. Surely there’s a YouTube video or two. Is that a common thing to have to do? Cut coils?

 

[thumper]

First off: 

That spring doesn't look broken, the end was cut and polished. If that's the case, your "tuner" is a hack. Leaving a spring cut and not collapsed and closed properly is unacceptable. And if the spring guide was made without a steel slip washer for the spring to bear on, that's another strike. Please never recommend whoever did that work to anyone. 

Have you tried cocking the gun with it assembled but without the spring in it? That would eliminate the variable of coil bind or other spring and tophat related issues. 

I've seen them get hard to cock from worn cocking linkages coupled with sloppy fitting OEM cocking shoes. Your aftermarket shoe should make up the difference, but check it just in case. 

Also, the way that the face of the latch rod looks peened on the piston face makes me think it may be a little on the "screwed in too far" end of things. Lots of these little things can stack up and cause enough slack in an already iffy design to cause the TX to not cock. 

But if it happened all of a sudden, then who knows. But at this point , it's seeming like some kind of linkage or latch rod related problem from here. Hope you get it fixed. 

 

[Barkley9]

I lied. I can't leave it alone. It's eating at me.



willy and thumper.... with the compression tube and piston tube in place it will engage the sear and set the safety WITHOUT the spring. Thank you for that suggestion. So.... I spent a bit of time and literally cut and dug out the broken delrin guide, collapsed the top spring end, refinished it and polished the ends. (Thanks to shootingatdawn and verminhuntersTV on YouTube)

I cut 2 coils off the FAC spring, collapsed the end, refinished, and polished the ends.

The FAC spring is now about 206mm and the tuned spring is about 222mm

I'll try them out tomorrow to see if these changes make any difference

 

[Barkley9]

I tried out the springs today plus I had ordered the 12fpe spring from Pyramyd, which came in today so I tried that one too. The TX engaged the sears, cocked, maybe 75% of the time and never engaged the safety with any of the springs. So, it HAD to be something simple, and it was. Even though I had installed the ARH stock bracket and the screw seemed to sitting flush. I thought maybe this might be a problem after all. So I took a brand new 1/2" drill bit and removed maybe a couple of thousandths from the mounting hole (held drill bit in my hand and turned), and it took a minute or two. Now the screw sits ever so slightly below. I noticed that the cocking arm had areas where it was hitting the screw, so I gently filed away the point areas. (I did not have an epiphany, please see the links below) I put it all together and it now cocks and engages the safety 100% of the time. I left the new 12 fpe spring in it with the original top hat to give a little more pre-load (new term I learned this week). Tested with some JSB 18.13gr and got an average of 606 fps for a little over 14 fpe. This will probably go down as I work the spring. I've got a new FAC spring, ARH piston seal, and lubricants on the way. After these past 2 weeks, I can do my own tuning now.....an old dog learns a new trick (and will keep learning). 

For the stock bracket, this is where I found the info...

https://johnshortell.com/air-arms/

https://www.tapatalk.com/groups/yellow/tx-200-mkiii-cocking-problem-and-solution-t87198.html



Thank you for all the input. Very much appreciated!

 

[Moog]

Barkley9, as frustrating as all that was that's the best way to learn. Nothing beats hands on experience and it sounds like you gained a lot of knowledge.

Congratulations on a job well done.