old 98 keeps cycling

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   Hi!

I have one of the old tippmann 98's which I've heavily hacked apart and modified. For a year or so it's worked fine, but when I pulled it out of the closet this spring to play, it doesn't work!

For some reason, the gun just keeps cycling, (firing over and over), as if the thumb doesn't engage the sear. This has boggled my mind for a while, because everything looks fine to me, but as soon as I fire the thing it doesn't work. The weirder thing, is that sometimes it DOES work fine for a bit!

Honestly, this is just making me go bonkers. I've taken it to a shop, and aside for the fact that I ground down the frame so it's basically just the tube and part of the trigger, it "should" work like it did last year. Any thoughts on the subject? I would post pictures, but it probably wouldn't tell anything since it looks fine to everyone who's seen it. It's one of the original 98's, so it only uses the pins to hold everything in place, (springs, thumbs, etc).

Thanks

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mrfranswa Members Profile Send Private Message Find Members Posts Add to Buddy List Member Joined: 18 August 2007 Status: Offline Points: 6	Post Options Post Reply Quote mrfranswa Report Post Thanks(0) Quote Reply Topic: old 98 keeps cycling Posted: 05 May 2008 at 7:38pm
	Hi! I have one of the old tippmann 98's which I've heavily hacked apart and modified. For a year or so it's worked fine, but when I pulled it out of the closet this spring to play, it doesn't work! For some reason, the gun just keeps cycling, (firing over and over), as if the thumb doesn't engage the sear. This has boggled my mind for a while, because everything looks fine to me, but as soon as I fire the thing it doesn't work. The weirder thing, is that sometimes it DOES work fine for a bit! Honestly, this is just making me go bonkers. I've taken it to a shop, and aside for the fact that I ground down the frame so it's basically just the tube and part of the trigger, it "should" work like it did last year. Any thoughts on the subject? I would post pictures, but it probably wouldn't tell anything since it looks fine to everyone who's seen it. It's one of the original 98's, so it only uses the pins to hold everything in place, (springs, thumbs, etc). Thanks

ShortyBP Members Profile Send Private Message Find Members Posts Add to Buddy List Moderator Group A G F Y Joined: 10 June 2002 Location: United States Status: Offline Points: 5034	Post Options Post Reply Quote ShortyBP Report Post Thanks(0) Quote Reply Posted: 05 May 2008 at 11:06pm
	Have you tried a new drive spring? Will it still do this with your hand over the end of the barrel (creating blowback)? My guess is that the sear and/or the ledge on the hammer is worn. Worn sear is a pretty standard issue, especially on an older gun

mrfranswa Members Profile Send Private Message Find Members Posts Add to Buddy List Member Joined: 18 August 2007 Status: Offline Points: 6	Post Options Post Reply Quote mrfranswa Report Post Thanks(0) Quote Reply Posted: 05 May 2008 at 11:14pm
	nope, it looks perfectly fine. The pin which held the thumb in place was not the correct one. It was slightly thinner than the standard issues. I am HOPING that replacing this will fix the problem, (which would reduce the wobbling of the thumb). I will try this tomorrow. Too late to test it now :P

mrfranswa Members Profile Send Private Message Find Members Posts Add to Buddy List Member Joined: 18 August 2007 Status: Offline Points: 6	Post Options Post Reply Quote mrfranswa Report Post Thanks(0) Quote Reply Posted: 07 May 2008 at 11:42am
	bah, no luck, the gun keeps cycling. I moved onto the next possible, (which is the spring which holds the thumb is too weak), and replaced it with a smaller spring I found at a hardware store. When I fired the gun, instead of perpetually cycling, it only did the two fire, (which means the bolt did not have enough force to put itself back onto the thumb). This means there is two possibilities which come to mind now. 1- the spring is WAY too strong now, and it is stopping the sear, or the more possible 2- not only was the spring too weak, but the o-rings on the sear need to be replaced. Sadly, the paintball dealer where I live does not carry these o rings for the sear, so I may be using my p-90 this weekend instead of my famas :(.

oldpbnoob Members Profile Send Private Message Find Members Posts Add to Buddy List Platinum Member Not old, Not noob. May be Dave's grandma Joined: 04 February 2008 Location: Yankee Stadium Status: Offline Points: 5676	Post Options Post Reply Quote oldpbnoob Report Post Thanks(0) Quote Reply Posted: 07 May 2008 at 12:15pm
	Have you done any modifications to the internals? Are you using the stock bolt, powertube etc? Also, what O-rings are you talking about? The sear doesnt have any O-rings. Do you mean the O-ring on the rear bolt?
	"When I grow up I want to marry a rich man and live in a condor next to the beach" -- My 7yr old daughter.

mrfranswa Members Profile Send Private Message Find Members Posts Add to Buddy List Member Joined: 18 August 2007 Status: Offline Points: 6	Post Options Post Reply Quote mrfranswa Report Post Thanks(0) Quote Reply Posted: 07 May 2008 at 6:26pm
	isn't that what the rear bolt is called? Well whatever. I tried with a few different springs to hold the thumb. Either the gun cycles repetitively, (spring too weak), or it perpetually cycles. I'm just going to drop it off at the local shop and have them look at it. And no, no inernal modifications. All were superficial.

Mack Members Profile Send Private Message Find Members Posts Add to Buddy List Moderator Group Has no impulse! control Joined: 13 January 2004 Location: 2nd Circle Status: Offline Points: 9906	Post Options Post Reply Quote Mack Report Post Thanks(0) Quote Reply Posted: 07 May 2008 at 7:28pm
	The sear is the part that catches and holds the rear bolt (also known as the hammer) to the rear. I recommend a quick perusal of the schematic section of your owner's manual so that we are all referring to the same parts if this discussion progresses. If you don't have a manual (since you said it was an old marker) they can be accessed from the main page of the Tippmann website by following the "customer service" link. I don't know if they still have the manuals for the original 98s up or not, but the new ones are quite similar. Edited Note: I found a PDF version of the original manual at this location. Edited by Mack - 07 May 2008 at 7:29pm


oldpbnoob Members Profile Send Private Message Find Members Posts Add to Buddy List Platinum Member Not old, Not noob. May be Dave's grandma Joined: 04 February 2008 Location: Yankee Stadium Status: Offline Points: 5676	Post Options Post Reply Quote oldpbnoob Report Post Thanks(0) Quote Reply Posted: 07 May 2008 at 8:52pm
	www.model98.org also has a printable manual for the original 98. That's where I got mine.
	"When I grow up I want to marry a rich man and live in a condor next to the beach" -- My 7yr old daughter.