Metadyne Thumper - Issues and remedies

[Chrisrook1]

Can agree that when they function, they’re fun, great shooters. Bought one used and working a few years back, a lot of fun on the field until the Clippers valve went out, now finally taking the time to put her back together and out there!

[XEMON]

You can try ...
The best case scenario: it shoot
The worse case scenario: the piston get screwy and need to remove o-ring and add a reg

Likely scenario: something gonna leak, something gonna bind, kinda shoot ... Sometimes and leak other ...

When they shoot they are great little shooters 👍

[Rainmaker]

So I have a question... I've got one of these bad girls now. If I just put a 12ie in the bucket changer and dry fire it, am I going to damage something? Do I need to put an inline reg on it? I'm really psyched about this thing, but I'm timid about shooting it, at least until I learn more, and feel confident in not going to break something. Sorry for the noob questions 😅

[RuleOfSines]

Quick question...
The end of this instructional video, the guy says the best way to lube it is to cram some Vaseline in the ASA hole, and you're good to go...? Is that true?

https://youtu.be/dxORumSkHGU

Well, kinda..

The itty bitty clippard valve inside there is not suitable for liquid lubricants, so the 'couple drops of oil' method is not recommended. However, the vaseline can also gunk up the inside, and the main piston can benefit greatly from lubrication.

Whenever I think mine needs lube, I take it all apart and lubricate that main piston directly. If you have no leaks, but you do have low velocity or a noticeable delay between when you pull the trigger and when it actually fires, you may need to do the same.

If on the other it is working fine and you're just looking to maintain it for now then I'd say yeah go for the dab of vaseline.

Fun note: I think I may actually now own the Thumper used in that video.

[Rainmaker]

Quick question...
The end of this instructional video, the guy says the best way to lube it is to cram some Vaseline in the ASA hole, and you're good to go...? Is that true?

https://youtu.be/dxORumSkHGU

[80F100]

Great to see great help and feedback from members on this. Following...

[Killerito]

Well got one working
one needs the hammer removed which means drilling the body.
have a parts one I’m trying to get from Canada so we shall see if I can work that out.

[XEMON]

Got mine working too.
the press fit rods were slipping, had to drill them and bolt them to the breach assembly.

[Kit]

I have a working thumper. To keep the hammer from bending clippard valve, I put a button on the valve stem. So the hammer can slide across the face instead of digging into it or wacking the stem and bending it. My thumper came with a metal piston so i don't have the bending problem. Not sure what version it is. To keep co2 from locking it up, you should run an external reg. set at 300 psi. You can still use the internal reg for velocity adjustments. I think the internal reg does not have enough bias( I think that is the term). There isn't enough difference in the piston size if you compare it to other regs. If anyone wants to send me their thumper, I'll take a crack at fixing them.

[Chuck E Ducky]

I was just going to tag him. He’s got his working great and shoots it all the time but he modified it a bit. He runs his on 12g to so he must have a fix for that.

[Jonnydread]

capitalpaintball had a new piston machined that I believe fixed most of the issues associated with the original one

[Killerito]

No thumper experts ?
I just bough 2 with the same issue. They fire in the breech open position but not when the amber is released.

[Siress]

Supposedly there was a thread on MCB2.0 on this topic. Guess this could be it's revival, though I'd rather see it get it's own subforum. It seems there are >300 of these guns in circulation and neigh a working one in sight, for having said it is working now means it is broken.

Problems mentioned:

• Bent pistons
  • Prevalence: 9 of 10?
  • Occurrence: ~2000 shots after piston replacement?
  • Root cause:
  • Remedies:
    • ?
• CO2 induced seizing
  • Prevalence:
  • Occurrence:
  • Root cause: O-ring swell?
  • Remedies:
    • Only use HPA.

Edit: You know what we need? A wiki for paintball tech info.