TF-89, RS-2 and others in this family, found a piston seal that will work

[70GTvert]

Since I picked up a pair of these it got a buddy interested who picked one up. Now mine were fine, needing nothing more than a lube tune. His, however, was weak, shooting only 840 fps in .177. At first I thought it was the cold, being only 25 degrees when we tested on the chrony. But after taking it apart, it was clear the seal was scuffed. Humm, what to do?

I never saw anything on replacement piston seals for these. But after a little comparison, I noted the spare seals in the QF2 kits for the B3 from South Summit looked similar. Yes, it was deeper, and no, it did not have a hole in the center for the screw, but both of those were easy to remedy. Cut down the skirt to the same depth as the one on the RS2 and then drilled a hole in the center with a slightly larger countersunk hole for the mounting screw. After reassembly, it chrony at 955+ or -10 fps with crosman 7.9 hp, and 990 = or - 15 fps with Beeman 7.1 hp's.

Looks like for $8 we can get a seal that will work, + a spring that will not only help our B3's, but can also give decent #'s in a Gamo Big Cat.

Kinda makes sense, as they are both made by Industry brand.

[billharmon2]

Thanks for the info. I have an Apex small seal coming to see what I can do with it for my RS2. If you need a spring you can get it from Umarex.

[70GTvert]

Thanks. Do they have a web site? I noted it is far longer, but same diam. as the JM E3650. That seal, if it is like the Apex I have, may work, but will require a washer for the center since they have larger holes than the Beeman one. I found it easier to make a hole than to try an reduce one.

[billharmon2]

There is a link to their site in the mall. I am going to see what I can come up with for the seal. Someone also told me to try Compasseco for parts. I really like these guns and would like to have extra parts in case I need them.

[leftcoast1]

www.umarex.com You can get the piston seal for the Walther Force 1000 and it will work. Buy a couple cause the shipping will kill you. lol

[70GTvert]

Sorry, could not locate that section from Umarex. Are they $8 or under?

Here is another tip. After looking at the Kermit Air Club Beeman disassembly instructions where the use 4 bolts to get past the trigger and compress the spring, I knew that there had to be something better. And I was right. I made a tool that is one piece, where you don't have to worry about lining up all those bolts and keeping them on the head of a spring compressor. Sorry no photos, but I will give a good description.

I found that a 18mm socket which has an outside diameter of 1" and a total depth of 2 1/2 " would just fit into the tube and be deep enough to get past the trigger pins. To get past the pins holding the trigger in place, I took a grinder and cut a slot on each side 1 3/4" deep and 5/16" wide. This gets you past the pins, but the trigger housing itself also gets in the way, so another slot at either the top or bottom again 1 3/4" deep but 3/8 wide will allow you to clear the trigger housing.

Now mine fit snug, but it did fit. However, I did take the grinder and thin down the sides ever so slightly until it was not so snug. Perhaps going with slightly less then 1" in diam may be better, maybe via using a 17 mm socket. Sure works fine and a lot easier than that 4 bolt method.

[RCnMo]

This works just fine for me.

http://www.gatewaytoairguns.com/airguns/forums/thread-view.asp?tid=7986&mid=57768#M57768

[70GTvert]

Looks nice, but mine required no welding or bending of sheetmetal thus may be easier for those with limited equipment (I do have a mig), plus I have to think that the support mine gives, over a larger portion of the spring base, which is plastic in these (or at least the RS-2), has to have some benefit. Perhaps not, then this does provide another good option. I like your solution to the seal. His had slight gouges, but IF i find one loose like that , I bet I can do the same thing with a C clamp, 2 sheets of steel and a hair dryer (you would be amazed at how pliable that seal stuf is when hot. I "fixed" a gouge on a B-3 with a solder iron, just kinda"pushed" material from low on the skirt up to the gouge and filled it in, melting together.)