Z-grip RT Classic - rebuilt!

[athomas]

That is a urethane oring? It looks quite dark in the pictures. I would have guessed it was a buna oring as well. Try a harder 90 durometer urethane oring to see if it helps.

You can't tell if its an updated reg piston assembly. If it doesn't leak out the back when you are shooting at the desired velocity using a red or grey bolt spring, then it is probably an updated piston assembly. If it doesn't leak out the back at really low velocities or at a setting that won't allow the gun to shoot, but starts to leak as you increase the velocity, then it is probably an older assembly.

The shims in between the halves will allow you to experiment with reactivity without filing down your pin. Since you have a shorter 0.740" pin, you shouldn't need to file it down if you use the shims. Don't use too many shims. Too many shims will cause the top to squeeze the oring on the pin and reduce your reactivity. If you have to press the on-off assembly into the valve with quite a bit of force in order to get the valve into the body, then you have too many shims installed. If the on-off assembly fits nicely and the valve slides into the body without restriction, then you are fine.

[Pghp8ntballer]

Yes, it is definitely urethane. I bought a standard set of 10 each from mcmaster carr. They are all black, not the expected clear.

Are the ULT and L10 shims the same? So simply unscrew the two halves of the on/off, put in a shim at a time and reassemble?

Once I get the gun up and running, I will tune for the RT.

The only other odd situation I had was when I first aired it up and did not leak, It was shooting 350 fps or so (with a chrono). I turned it out quite a bit but it never dropped. After about 20 cycles/shots or so it started the leak. It has the gold mainspring on the bolt.

[athomas]

ULT shims are 0.005" thick and level 10 shims are 0.010" thick. Two ULT shims equals one level 10 shim. Yes, just unscrew the two halves and put a shim over the threads and reassemble.

If you aired it up and couldn't get it to shoot under 350 fps, even after turning the adjuster out quite a bit, its most likely that your regulator seat oring is leaking.

[Pghp8ntballer]

So that just reiterates your initial thoughts. Even better. ULT and L10 shims are the same ID and OD then?


Why does the regulator piston in my valve look completely different than the AGD blow-up diagram of the retro valve and in the parts break down?

[luke]

The type of damage to the oring looks to me like it's getting clipped off as it's being compressed to squeeze into the cavity. I would chalk this up to being the wrong o-ring and or material type. I have seen that exact damage to o-rings in the prototype stage of making and designing parts. Generally it has to do with the wrong parameter spec for the o-ring being used, for example stretch, compression, groove size and cavity diameter. Since we know the AGD parts are to spec I would bet that the spec of the o-ring is incorrect including the material type.

[Pghp8ntballer]

Hmm. Its a 70D 012 urethane oring. Good to know.

Luke, Athomas, anyone else... should I purchase a new reg piston while I am at it? Or should I use the one I have?

So my parts list to order are...

genuine AGD RT parts kit
L10 rebuild orings
RT pin (to have as a spare)
one pack of ULT shims
Spare bolt foamie
new reg piston???

[luke]

Its a 70D 012 urethane oring.

I'm simply saying that I've seen that exact damage and it was due to in correct specifications. The "odd part out" here is the non AGD spec o-ring so if there is no visual damage to the piston or cavity the first thing I would do is install the correct o-ring. I do suggest that you remove the o-ring and closely inspect the parts under a magnifying glass to see if there is any damage. I would only replace the piston if it's damaged beyond repair. If there is a burr or something, that can probably be repaired...

[Pghp8ntballer]

Understood. I used the urethane over buna to prevent a possible issue. But I will order the genuine agd kit. Unfortunately I do not have a magnifying glass.

[luke]

I have always had a magnifying glass in my gear bag, found many damaged o-rings. I even inspect the new ones before and after installing them.
http://www.ebay.com/itm/Loupe-Double...UAAOSwnipWU5q~

[Spider-TW]

Off spec or not, the o-ring shouldn't normally reach the vent to get nibbled upon.

You can use non-AGD o-rings as long as they are the right size and material. I bought a bunch of good banjo bolt o-rings from mcmaster, then got my RT to stop chewing them.

Avoid Chinese o-rings. I've seen some absolutely terrible round things they sold as o-rings. That was one of WDPs A1 angel problems; the Chinese o-rings were bad out of the box. I have one where I had to replace most of the o-rings just to get it running the first time, brand new.

[Pghp8ntballer]

I noticed the el-cheapo orings I have from Harbor freight are clearly not the correct size. I was able to put new banjo bolt orings on since I had ordered a 100 pack or 90D buna 009 and other sizes from McMaster Carr a while back. Their orings are usually pretty good. I only have like 90 more of those 90D orings for the banjo bolt. They were so hard to put on due to the duro, I doubt I will need the other 90 I have, lol.

[luke]

If you have a level 10 bolt, the regulator piston assembly needs to be the newer higher pressure version as well.

Re-tuned not replaced.

[Pghp8ntballer]

cool beans there!

[luke]

Off spec or not, the o-ring shouldn't normally reach the vent to get nibbled upon.

I would wager it's getting clipped on the leading edge of the cavity during install not the vent hole.

[athomas]

Re-tuned not replaced.

Yes, but most don't have the ability to retune them like you or a few others here.:)

I agree that the oring is probably getting pinched on the install into the cavity, or is getting pinched in the groove once the pressure hits it if it is the wrong spec (ie; too loose or wrong dimensions).