RT Classic Issue (didn't think this through all the way)

[Mondoatx]

Hey guys,

Got a RT Classic in the mail last week and got some fittings for it today in the mail... one of them was a male quick disconnect piece...

Before I put it in I noticed that it had something inside the male QD piece... back in the 90's these were 1 way valves... allowing air in but not out (like you would find in a fill nipple on a compressed air tank)... anyways... I put it on with the one way valve in... not thinking it through...

Put air on it this afternoon (after replacing the seals last night)... and the bolt was acting all kinds of weird...

I am now wondering if this is due to the one way valve... I took the air off the gun to check some different things (and pull that one way valve out of the male QD piece)... but now the banjo bolt is VERY hard to get out... which leads me to believe it is retaining air pressure due to the one way valve. It was able to fire a single shot after taking off the air... but I get the feeling it has maybe enough air in the gun to make the banjo bolt tough to get out but maybe not enough air to push the sear pin forward or cycle...

Now I am trying to figure out how to relieve the (possibly fictitious) pressure without taking the chance of blowing an o ring on the banjo bolt or something else that may not be good...

Or should I just nut up and unscrew the banjo? I can see that it might be tougher to get out because I just put air to it... but not really sure.

Let me know your thoughts. The RT Classic is a new beast to me... but last night when replacing seals it seemed very similar to the xvalve in my RT Pro.

Oh... and one more possibly pertinent detail... the male QD piece is coming out of a 90 degree fitting coming out of the first hole in the rail (farthest from the shooter) on the right hand side of the gun.

Thanks guys.

M

[blackdeath1k]

I'm guessing your holding 5-600 psi behind it. 6 is about where my classic rt quits cycling but still has pressure. If it were me I would undo the quick disconnect while wearing gloves. Or slowly undo a fitting on the load side of your check valve to bless the air off.

[Mondoatx]

Blackdeath,

That is the problem... the quick disconnect is already disconnected but it is retaining pressure because the male piece (the nipple) has the one way valve in it...

So it seems to me the only was I can do something about this is to unscrew something... whether it is a fitting or the banjo or one of those set screws that plug the holes in the rail that are not in use...

When you say check valve... are you talking about a slide check? If so... don't have one of those on there...

Argh!

[nak81783]

Face shield, gloves, small punch, tiny taps on the pin to slowly bleed air until you can just push it in by hand, if you can't just push it in by hand from the start. I wouldn't unscrew the fitting with that much pressure behind it.

[captian pinky]

unscrew the fitting slowly wear safety glasses you will be fine. once it begins to hiss let it do so until it stops.

[Tunaman]

unscrew the velocity adjuster on the rear...slowly until it leaks.

[Mondoatx]

Thanks for the input everyone...

Unscrewed the male QD piece slowly... no air vented... so I proceeded to take things apart... it became apparent when I got the body separated from the rail what was going on...



Looks like the middle O ring on the banjo bolt came out of its' groove somehow and now it is wedged between the rail and the bolt...

Anyone ever seen anything like this before? Did I do something to cause this to happen? When I put the O rings on the bolt last night everything seemed to be in place... I also applied just a bit of oil as I was worried about those o rings rubbing on things if they were dry.

I am sure I can force the bolt out of the rail... but I would like to salvage that O ring if possible as I do not have another.... I am sure forcing it out of the hole will shred that O ring... if it isn't already toast...

Let me know your thoughts guys...

Thanks again!!

[Mondoatx]

Could see the O ring was already shredded... so I went ahead and took the bolt out...

I am going to order some more from AGD in a moment here...

But I am interested on anyone's opinions on how this happened... like I said before... Last night when I replaced all the old orings on the banjo... I made sure they were all snugly fit into their grooves... and when I re assembled the gun after replacing all the seals it slid in and tightened easily... I also oiled them because the gun had not been shot in years and you could feel the old ones dragging when you removed/installed the bolt when they were dry...

Let me know your thoughts... if I did something wrong that caused this I want to learn and avoid it in the future.

Thanks.

M

[nak81783]

Did you use orings from AGD? Assuming you used the right size, if you used the wrong material or durometer, they'll be too soft and may get displaced from pressure. Safest bet is to get them from AGD or Tunaman. They're cast urethane 90 durometer.

[Nobody]

As i was told, the best way to put an RT together is to have the front frame screw slightly loose, then put in the valve. Tighten up thevqlve and the the frame screw.

Orings can look good, not be old but then when put to the test fail. Could be a bad batch, its time or nicked it on something. Banjo bolt orings are the most common oring to change on them.

Should those orings (the banjo bolt orings) be urethane and not buna?

[Tunaman]

There was an update to that banjo bolt too. I do not know if you have the old one or not...

[captian pinky]

what was the update?

[going_home]

There was an update to that banjo bolt too. I do not know if you have the old one or not...

Interesting.

[Spider-TW]

what was the update?

The middle groove needs to be closer to the bottom o-ring. Maybe the bolt surface above the middle o-ring has some room to be a little larger. The chamfer on the rail and the shoulder of the banjo bolt don't hold the o-ring in.

Those are 90D urethane o-rings. Softer o-rings can shift and extrude more easily, as well as let the valve shift back, causing some of the usual "missing rail bushing" problems.

You can try a ninja regulator shim on the banjo bolt to pull it down. That lasted a little while on mine. I eventually modified the rail though, which cleared it up.

[captian pinky]

The middle groove needs to be closer to the bottom o-ring. Maybe the bolt surface above the middle o-ring has some room to be a little larger. The chamfer on the rail and the shoulder of the banjo bolt don't hold the o-ring in.

Those are 90D urethane o-rings. Softer o-rings can shift and extrude more easily, as well as let the valve shift back, causing some of the usual "missing rail bushing" problems.

would be nice if we put all this info in a single thread and sticky it.

thinking some pics of the old and new banjos ( with dimensions) and a pics of old and new rails.

[Spider-TW]

would be nice if we put all this info in a single thread and sticky it.

thinking some pics of the old and new banjos ( with dimensions) and a pics of old and new rails.

I was looking at the pics in the online store of the banjo bolt. It may just be the old pic as it looks the same. I'm guessing that the taper from the top o-ring groove to the middle groove is for clearance of the banjo against the rail. That spot needs to be lower and/or a larger diameter. The banjo appears to move some as you shoot, even with 90D o-rings, as you always find this failure on the forward side of the banjo. You think you got it fixed, then the o-ring pops while you are playing.

While I modified my rail, a modified banjo would be an easier fix if you could get the dimensions and machining right.

If you remember the story with the original (level 5? no allen socket) field strip screws, they would fail over time, shearing off or bending beyond usability. I had one that bent. TK explained that around here, something about the threading process. I would check that before making a batch of banjo screws (that's if AGD doesn't have an improved one already).

***

Considering how many of us know about the power feed plug upgrade and such, I keep wondering about the differences in the changes to the RT classic as well as it's total production numbers.

[blackdeath1k]

There have been pictures posted of the new and old classic rt rails and banjo bolts posted recently. For the life of me I don't remember what thread they are in.

[captian pinky]

i know the rails were posted wasnt sure about the banjos.

Calling Bunny to right an article........hoping this works like when we call tk and he just appears.

found the other thread

https://www.automags.org/forums/showt...72#post2905572

[Mondoatx]

Hey guys,

Yes... they were AGD O rings out of a fresh RT Classic parts kit... so I don't think that was the issue.

Waiting on some more Banjo O rings...

I will try the process for assembly Nobody mentioned...

I also discovered the sear had a chip missing out of the edge that catches the bolt... so it wasn't exactly a sharp edge where it catches the bolt (ordered a replacement)...

In addition the Banjo bolt middle o ring was shredded...

And I had a 1 way valve in the male end of the QD...

When I aired it up it was sometimes burst firing and sometimes getting bolt stick... Not sure if this was caused by any of the above issues because that oring on the field strip was chopped and it kept me from eliminating possible suspects... I had replaced all the seals prior to this.

Anyone care to weigh in on which issue is causing the bolt to behave this way? Or is it something else entirely?

As always... thanks for the support of the community!

M

[luke]

I also discovered the sear had a chip missing out of the edge that catches the bolt... so it wasn't exactly a sharp edge where it catches the bolt (ordered a replacement)...

When I aired it up it was sometimes burst firing and sometimes getting bolt stick...

The sear is likely the cause, you also need to check the bolt edge that catches the sear for wear. (Inspect it with a magnifying glass)

[Spider-TW]

Mondo, would you take a pic similar to the ones in the thread below, for comparison?

i know the rails were posted wasnt sure about the banjos.

Calling Bunny to right an article........hoping this works like when we call tk and he just appears.

found the other thread

https://www.automags.org/forums/showt...72#post2905572

[blackdeath1k]

Sounds like your rt is one of the Original classic RTs that had all of the problem parts. First gen rail, first gen banjo, and first gen carbon tipped sear.

[Mondoatx]

Lucky me...

At least the banjo and sear are easy (read cheap) fixes... Rail is a bit more expensive...

Sounds like your rt is one of the Original classic RTs that had all of the problem parts. First gen rail, first gen banjo, and first gen carbon tipped sear.

[Mondoatx]

Spider,

Yes would be happy to. Will get to it tonight.

Mondo, would you take a pic similar to the ones in the thread below, for comparison?

[Mondoatx]

Luke,

When I inspect the bolt edge... what am I looking for exactly?

I am assuming if I need a magnifying glass I should be looking for something possibly tough to notice? A minute detail of some sort?

The sear is likely the cause, you also need to check the bolt edge that catches the sear for wear. (Inspect it with a magnifying glass)

[captian pinky]

It should be a sharp triangular corner. If it has a chunk missing replace it.


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[Spider-TW]

first gen carbon tipped sear.

Carbide, but that did make me wonder for a second if there wasn't some new carbon material that would work.

It's very interesting how the carbide fails of brittle fracture while we (or many of us) have trouble wearing out a regular sear.

[Tunaman]

Carbide, but that did make me wonder for a second if there wasn't some new carbon material that would work.

It's very interesting how the carbide fails of brittle fracture while we (or many of us) have trouble wearing out a regular sear.

Whatever AGD did to the hardness of the new sear and bolt they got it right...because bolt and sear wear is almost non existant anymore.

[luke]

Luke,

When I inspect the bolt edge... what am I looking for exactly?

I am assuming if I need a magnifying glass I should be looking for something possibly tough to notice? A minute detail of some sort?

I use a magnifying glass to inspect all my AGD valve parts especially orings. As far as the edge of your bolt goes, it will be an inconsistency of some sort, if there's something wrong you will know when you see it.

[Mondoatx]

Did the best I could... couldn't quite match the angles or lighting...

Let me know if you would like me to post them on the referenced thread...

Also... I don't see a huge difference betw what is posted on that other thread and what I have here... if someone can/does notice the difference spell it out for me.

Thanks all!

Mondo, would you take a pic similar to the ones in the thread below, for comparison?