Tuning Repairing a 1998 Air Arms Pro Elite

[jegarh]

You guys inspired me. My Pro Elite left handed in .22 suddenly quit shooting. Since I had some 30 mm seals that looked like they might work, I think they are R1 seals, and they fit when modified. I had to shorten so the back of the face would rest on the face of the piston. I went through my collection of glues and settled on the clear non foaming gorilla glue. I will see how this works. So far 500 pellets later it is still doing what it is supposed to do. If it fails, it is easy to break down and try something else.

 

[Bill_S]

Good to hear of your success! I might be taking too much time thinking about various fixes.

I did place an order with Airgun Spares (UK) for OEM seals, some springs to experiment with, plus a few odds and ends for spares. It might take a while to reach me though.

I was going through other items in the basement and found another PE seal that looks just like the ones that I got from Maccari. I was probably going through a phase gathering spares to keep the rifle going. This one is in a package from 2001, and came from someone named Mike at Customwerks Airgunning.

With my three existing JM seals plus the three OEM seals coming on a slow boat, I'll be set for a while.

 

[Bill_S]

I was looking at the parts list for the Pro Elite and noticed that most parts are prefixed with either "TX" or "BB". The e-clip for the cocking pin, for instance, is supposedly the same part as for a TX200, so I'm beginning to believe that parts common with the TX200 have the TX prefix. The prefix "BB" might stand for Break Barrel, and be unique to the Pro Elite.

If true, this makes finding parts for Pro Elite rifles much easier. There's a lot of overlap between the two.

 

[Bill_S]

Here's the trigger assembly with a high percentage of "TX" labeled parts.

 

[Bill_S]

I thought that I'd update this thread. Work is progressing in fits and starts. The order from the UK for OEM seals and springs is stalled in Chicago somewhere.

In the meantime, I ordered a brass lap to see what I could do with it.

I ordered the 1-1/8" diameter model because I don't have a lathe to turn a larger one close to 30mm. It has to be expanded more than desired to fit, but it's OK. Unfortunately, the shaft that connects to the brass lap is too short to reach far into the compression tube. I can get about as far as this...

The shaft is a large 3/4" diameter, so I can't chuck it into my drill press. I resorted to turning by hand. There's a tight spot in front of the trigger opening, and it may be an out-of-round stretch because of the punched slots and holes in that area.

To make this work, I'll need to extend the shaft and to make it small enough at the free end to fit the drill press. I briefly looked at a shaft coupler sleeve for extending it, but the coupler is larger in diameter than the work. It won't fit inside to allow the lap to reach. I don't have a lathe to center drill and tap for a 3/8" extension shaft. If I tried it on my drill press, I'd likely get the hole off-center and that would cause problems.

I'm still thinking about that.

I got some Loctite two-part glue and primer that is supposed to fill gaps between parts. The Maccari seal would be a good candidate for that adhesive because of how the seal fits the piston.

Expensive stuff!

While I had the original e-clips for the cocking lever pivot, I wanted spares. I found that a McMaster-Carr 3.2mm e-clip that works. It's a little stouter in shape, so it takes more force to insert. That also means it won't wander off as easily in the field.

 

[Bill_S]

Just for posterity, here are the measurements of some more parts for the Pro Elite...

Here's the cocking lever pivot and e-clips...

The barrel pivot and round spanner nut...

 

[Michigander]

Use the center head for a combination square to mark the center of the shaft, center punch, drill and tap. Fix a long bolt with the head cut off using a jam nut. Roll the shaft on a flat surface and bend the bolt until it stops wobbling. Make sure the shaft is vertical when drilling. Clamp in the vee groove of your drill press vice.

https://www.harborfreight.com/12-in-combination-square-set-63688.html

 

[Bill_S]

Thanks! That's probably what I will do. I need to visit the hardware store for some 3/8-16 all-thread rod.

I'm going to have to flatten the end of the lap's handle before drilling. They left a little center nub there when they cut it off. I know that I can't center the drill with that still there regardless of how well it is marked and center-punched.

 

[Duckfish]

Looks like chambers air gun spares has lots of parts. I have ordered from them with good results.

 

[Bill_S]

I just looked them up, and indeed, they do have a lot of different parts for the Pro Elite. Thanks for the lead! I'll make a note of that resource.

The parts that I ordered from Airgun Spares/Countrystore UK have been stuck in Chicago for two weeks now. I expect that it will get sent along any day now.

 

[Bill_S]

Work has been slow, but the parts from the Countrystore/ Airgun Spares in the UK finally arrived. Most of the delay in shipping was a stop in Chicago where the order sat for weeks.

I purchased three OEM seals, two piston rings, one e-clip (that's all they had in stock), a Pro Elite spring, and a Titan spring to fit a Pro Elite.

The Pro Elite spring sent must be UK-spec because the wire is significantly thinner than my U.S.-spec spring. It had a wire diameter of 0.128" with 31 active coils vs. 0.148" diameter/34 active coils of my original spring. The fit was loose over the original spring guide. Estimated spring rate is 31 lb/in vs. 48 lb/in of my original.

Here's a photo of the original Pro Elite spring (top) compared to the replacement from the UK. The difference is obvious.

The Titan spring sent is much closer to my original, but still uses a bit thinner wire at 0.141". It has 30 active coils, is nicely made, but is still a bit loose on the existing spring guide. The calculated spring rate is 43 lb/in which is very close to what the original US-spec spring is.

My conclusion? - Re-use my old spring and have the Titan for a backup. It would require new spring guides, but I can have those made when/if I need them. The link for Chambers in the UK shows two possible springs for the Pro Elite, so possibly one of them might be US spec. I may try to contact them in the near future to see about that.

The seals shipped looked very nicely made. They snap right onto the piston, but aren't tight without being glued. They can be pulled off again with little effort. They are possibly a urethane material that is more flexible than the Maccari seals that I pictured earlier. Also, they have a parachute lip around the edge. It has a significant outward flare.

 

[Bill_S]

I did more work on honing the compression tube. There was a tight spot just forward of the trigger, and it must be because of all the slots and holes punched into the tube in that area.

I marked the center of the bass lap's shaft...

Center punched it, and used a stubby center drill to make the pilot.

That was followed up with a 5/16" tap drill for 3/8-16 threads...

Then tapped 3/8"-16...

Then I used 3/8-16 all-thread to extend the reach of the brass lap...

This was chucked into my drill press. I swung the table aside to use the full length of the press for lapping...

I started with 90 grit (sounded like gravel in there!), cleaned up and switched to 220 grit, then to 360 grit. These lapping compounds were mixed with Norton honing oil meant for sharpening stones. I spent time on the area just ahead of the trigger where the fit was tight. The rest of the tube was OK.

After I cleaned up after the 360 grit lapping compound, I switched to polishing paste on the lap, and finally chased a bit of polishing paste in the tube with my "swab" for the last bit of polishing.

I used some needle files to chamfer the cutout edges on the inside of the tube. Finally, I used a little bluing paste on the freshly chamfered edges.

 

[Bill_S]

I popped a seal onto the piston (no glue yet) to assess the fit in the tube. Without any lubrication, this is as far as I could insert the piston...

When tugging and wriggling the piston back out, the seal popped off. That's concrete evidence that it needs glued on to be secure.

I can glue the seal and then chuck the piston in the drill press to sand the seal lip for a better fit.

I am trying an experiment in the meantime. I used some plant-based Camellia oil (meant as an anti-rust coating for woodworking tools like hand planes) to lightly coat the tube, and inserted the seal backwards, without piston, into an area that completely surrounds the seal. I avoided petroleum oils because of the possibility of swelling the seal, which would make things worse.

Then I heated the metal tube and seal with a hobby heat gun (not the heavy duty paint removing kind) until it was hot to the touch in an effort to get the seal to set a bit and conform better to the tube's size. After several cycles of heat, I let it sit for a day to see if it would take a set closer to the size of the tube.

It's not changing much, and the fit in the tube mounted on the piston is still very tight. It was an experiment, but I can still see the need for sanding the seal OD to fit. I hope that the urethane material sands well and is left with a smooth surface.

 

[wchilton]

I tuned a PE several years back. Don't recall what adhesive I used (if any) on the seal...I may have just left the seal alone if it was not worn. What I do remember is trying a McCarri spring and ended up switching back to the factory spring since it had a smoother shooting cycle. With that factory seal in backwards it looks like the lip hasn't closed completely. You may only need to size down the base of the seal.

 

[Bill_S]

My Maccari spring has the highest calculated rate of the four springs that I have on hand. It's thicker wire than the others. One positive aspect is that it fits the original spring guide nicely, but it has one badly squared end that will require work. Because of the higher spring rate and the un-square end, it's not really being considered for replacement. I feared that it would end up being harsh like you indicate with your experience.

Just to summarize, here are the springs that I have for it now with their calculated spring rates...

• Maccari spring - 60.5 lb/in
• Original Pro Elite U.S. spring - 48.2 lb/in
• Titan spring from Airgunspares.com (John Knibbs) - 43.3 lb/in
• Pro Elite replacement spring (UK spec? Also from Airgunspares.com) - 31 lb/in

Both the Titan and replacement PE spring are loose fits on the existing guide.

 

[Bill_S]

I've been busy with other things, and I've finally returned to the shop to work on this. I've glued the seal to the piston. I began by cleaning the piston with 91% alcohol, and the seal with soap & water first, followed by isopropyl. I applied the Loctite primer to the seal. It's meant for plastics. After drying, I squeezed out a mixture of the Loctite 3092 onto a piece of paper, and used an acid brush to apply glue to the piston's mating surface. The seal popped right on with no trouble. I let it cure for 24 hours.

This is the seal adhered to the piston afterward.

It won't fit into the compression tube as-is. It's much too large, so I will take some steps to reduce its diameter.

 

[Bill_S]

I made a little wooden right-angle fixture to hold sandpaper square when it is used on the drill press table.

After it dried, I chucked the piston into the drill press and indicated it to reduce runout. With some finagling of how it was chucked, I reduced runout to a total travel of 0.003" from true.

The seal is soft, and sanding it to a smaller diameter is just one step better than sanding a rubber band. I had to resort to 120 grit sandpaper to get any cutting action at all. I used a mirror to keep an eye on the business end as sanding progressed.

The unflared part of the seal that mates with the piston was about 0.025" too large in diameter, and because there is metal behind it, it can't flex. I spent a lot of time with self-adhesive sandpaper stuck to the edge of a file to address that particular area.

My old seal measures exactly 30.00 mm in diameter, so that's what I aimed for at the mounting area. The parachute flares well beyond that, but it is supposed to flex to a smaller size when used in place.

However, the seal + piston are still a very tight fit in the bore. The surface finish of the seal is fairly rough now. I hope that doesn't cause an issue.

The good news is that the adhesive is holding the seal on securely. Even after multiple trial fittings in the tube that required aggressive twisting and pulling to get the piston and seal back out, the glue held. It's good stuff, but very expensive and requires refrigeration.

 

[Gear_Junkie]

This is a superb thread with excellent pictures and explanations - THANK YOU!!!

 

[Bill_S]

Thanks!

If it were easy to find parts, and everything fit together nicely, there would be no need to create this thread. However, that's not the case. When I was looking around the 'net for repair information, I found very little. I decided to collect my experiences along the way to benefit someone else who may be looking for the same thing. And if I fail, I'll report that too.

 

[Bill_S]

I've finished repairing the gun, and it's now firing just fine. After four dieseling shots, I got an average of 766 fps on the first ten shots. I am using Crosman Premier .22 cal, 14.3 grain pellets to test it.

It took quite a bit of sanding to reduce the diameter of the seal to fit. Once I was able to hold the calipers at one end and have the jaws set to 30.1mm just slide over the seal with its own weight, I put it together.

Happily, my compression chamber is straight and true, with the only tight spot being where the trigger stud goes through. That's way at the back end of the tube where the seal doesn't ride in use. Once past that spot, I could tamp the compression chamber on carpet and have the piston increment downward about an inch at a time. I figured that with time, a tight seal will break in to fit even better. A loose seal never fits.

I reassembled the barrel to the compression tube and had to use a small clamp to hold the latch in. The latch has a milled spot inside that allows the pivot bolt to retain it. The spring was stiff so I couldn't just press it by hand to be able to insert the pivot bolt. The soft jaw clamp worked nicely.

After the bolt was inserted and the clamp removed, I adjusted tension and attached the lock nut on the other side.

Continued next post...