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Old 02-28-2012, 12:38 PM   #1 (permalink)
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RT Classic Un-boxing thread and banjo bolt tips (big pics)

With all the Classic RTs that float around, I wanted to start a thread with some particular tips for keeping them healthy, since they have a reputation for being troublesome. This is also a little about breaking down a new-to-you RT. I also want to collect others tips as well. The valve maintenance itself is pretty well covered elsewhere.

I put up a WTB for an old leaker of an RT, and tenchustealthx had one that fit the bill perfectly. This RT was known more for shredding the middle o-ring than simply leaking.

First things first. Upon extracting the RT from the wonderful amount of bubble wrap, I pulled the power feed plug. Lo and behold, it was of the older, most evil, feed plug of doom variety. Here it is on the right, with a newer plug on the left. That little bit of vertical face on the bottom of the right one is BAD.

The next thing was that the on/off pin was known to be missing. Pulling the on/off, you find that there is a pin, but it was broken. A good indication is that the whole pin sits inside the body. At least one end should be hanging out for it to work. It should be 0.750 inches long (maybe ground down as much as 0.030 inches less).

I turned a regular classic automag pin down to RT dimensions and polished the pin and the sear where they meet. New pins are available from airgundesignsusa dot com.

I checked the reg springs. The velocity adjuster was turned in further than I expected, but the springs looked good and properly smelled of grease.

The bolt was sitting up on the PT o-ring pretty high, but seems to cause no trouble.

I have read and noticed here that the body can shift and interfere with the banjo bolt o-rings, usually coming out. With the front frame screw sitting in its hole and the body pressed forward (as shooting will do to it), you can just see the edge of the body peeking over the banjo bolt hole. It's easier to see when you move it back and forth.

I ground that side back about 1/32 of an inch with a dremel and smoothed it up. That is not a sealing or indexed surface, so it doesn't hurt to push it back. The hole still looks round.

The regulator o-rings looked good and the inside was clean. There was some compressor grime in the reg piston cavity that I cleaned out, and then relubed the piston.

The banjo bolt o-rings were in good shape and the middle one that would get shredded looked new. Running it in and out of the valve, I felt around until I could feel the top o-ring seat and then start to crush. I wanted to get the bolt tight in between these two states. With a pretty good gap left between being tight and seating the top, I looked for a shim for the bolt. I found the Ninja reg "thick" shim (red-0.022") to fit perfectly. ***This setup did not hold at 950 psi. No damage, but it leaked after firing a while. This was repeatable. I changed to a thin ninja shim and finger tight and that seemed to satisfy it.***

With these changes I have been able to get the bolt in and out without trouble so far. I have only had it up to about 800 psi so far, and I will post up the results when I get more air for my old flatline or get my Ninja SHP on there.

Similar to a shim, here's a quote from AO about using an o-ring instead...
Originally Posted by 211
I was having this prob with my classic RT
if you slide an extra banjo bolt orings down tight to the head of the banjo bolt it will act as a spacer and will help keep that center oring from getting blown out
And an alternate to grinding out the hole in the body...
Originally Posted by cougar20th
One thing Ive learned to do when assembling my Classic RT's is to leave the front frame screw loose, Put the banjo in place finger tight, then tighten everything up from there, Never had a issue when doing that. If I don't I seem to always nick the orings because something isn't aligned & cant move into alignment.

Dont know if that will help your issue but its a nice little thing to help later on
I will also post a pic of the top of the benchmark trigger that I have filled in. Having read that the benchmarks are hard to RT, I think the circular recess at the top reduces the RT kick back on the trigger.

A general tip when removing automag valves and especially RT valves; put your left thumb on the back of the valve and press just enough to counter the bolt spring. This takes the side load off the field strip/banjo bolt and prevents hanging and wear. You pretty much have to do this when installing, but do it when removing as well. When I find a rail with a worn out bolt hole, I'll try sleeving it with some stainless tubing.

I count three complete turns on the banjo bolt from engagement to snug. I'm going to put some nail polish on the side of the bolt and match it on the rail to keep track of it.

For now, it's off to Luke's for a vert feed. Just couldn't help myself.

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Last edited by Spider!; 03-05-2012 at 11:08 AM.
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Old 02-29-2012, 11:16 AM   #2 (permalink)
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Good info Spider! I have a Classic and have issues with leaking. I will try some of your findings.
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Old 04-10-2012, 12:20 PM   #3 (permalink)
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Maybe a necro, but I just read this due to the link in the other thread. Thanks for the info and the plethora of pics. Cheers.
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