RidgeRunner’s Diana 34 project: Part Three

RidgeRunner’s Diana 34.

Part 1
Part 2

This report covers:

• Shootski’s request
• Cleaning
• The new mainspring
• Spring guide
• Assembly and lubrication
• Buttoning up
• Stock on
• How does she shoot?
• Where next?

Today I clean all of RidgeRunner’s Diana 34 parts, assemble the rifle with a new mainspring  and lubricate it correctly. We will learn many things today and I won’t spoil the ending for you.

Shootski’s request

Before I get into the work I will grant reader Shootski his request from Part 1. I had said, “The groove in the inclined plane that the breech ball bearing rides on still has most of its bluing. I saw a report on the Airgun Nation forum where the owner thought that the groove had been worn in the steel by the ball bearing, but what he actually saw was the inclined plane with no bluing remaining.”

After reading that Shootski asked, “Dark Sider would like to know some more.

B.B. wrote “The Diana 34 has a ball bearing breech lock that rides over a steel inclined ramp, until the spring pushes the ball over the steel ramp to lock the breech.”

5. Could we get a detailed photograph of this steel inclined ramp on a future Part? Please.”

There you go, shootski. The breech locking ball rides up the groove in that small ramp. As you can see, all the bluing is still on this ramp, which gives you an idea of just how unused this rifle is.

Cleaning

Cleaning the rifle is job one. But this old girl came to me almost squeaky clean. I ran a couple cotton swabs down inside the spring tube and they came out clean. There is nothing inside and that’s a gun that needs lubrication!

I wiped off the piston with a rag and the soot on the piston crown mostly went away. What was left I got with alcohol on a cotton swab.

Remember that I thought there was a corresponding patch of soot at the air transfer port in the spring tube? Well, it turned out to be just the shadow of a deeply chamfered transfer port. There was no soot inside the compression chamber.

Once the parts were clean it was time to lubricate and assemble. This took most of the 90 minutes this whole job took job. For lubricants I used moly grease, Tune-in-a-Tube and a couple drops of SLIP 2000.

The first lube was a couple drops of SLIP 2000 in the joint of the cocking link where it joins the bottom of the base block beneath the barrel. I worked the link back and forth but that didn’t change things too much

Since I showed you most of the parts during the disassembly in Part 2 I will show different parts today. And I’ll cover the one tricky place in the assembly of a Diana 34 — in fact, for many Diana air rifles.

The new mainspring

I looked through my stash of new mainsprings. It would be so much easier and less expensive for RidgeRunner if I could find a spring for this job and not have to buy him a new one. Most of mine were made from wire that was too thick for this job, plus they did not have a large enough outside diameter. Remember the huge clearance between the factory spring (OD 0.824 inches) and the inside diameter of the piston. I measured the inside of the piston in Part 2 at 0.950-inches, but on this time I measured it again at 0.925-inches. The clearance between the new spring (OD 0.854-inches) and piston is still large — just not as large as previously reported.

The spring I chose to replace the factory spring came from a Vortek spring tuneup kit I either never used or installed and removed again. It was dry all over so I don’t think it has ever been used. The wire diameter is 0.135-inches so it is larger than the 0.130-inch factory spring wire, but the metallurgy of the wire may give a softer push. I’ll just have to try it to find out. 

The new spring has 28 complete coils, compared to the 33 coils of the factory spring. That will give it less preload and I hoped that would make the rifle cock easier.

The factory mainspring (top) is longer than the replacement. The replacement has fewer coils and is of greater outside diameter, but the spring wire is 0.005-inches wider.

The Vortek spring guide did not fit over RidgeRunner’s trigger, and the piston rod in that kit shortened the piston stroke which takes power away, so the only part I used from the kit was the Vortek mainspring.

Spring guide

Remember I mentioned a hesitation in the cocking stroke in Part 1? Well the open end of the synthetic spring guide that receives the piston rod when the rifle is cocked had a couple rough spots on it where the piston rod had bumped it. They didn’t look large enough to cause that hesitation, but they were there.

The base of the spring guide, however, is broken off. It now looks like there is a thick synthetic washer and the guide that’s separated from it looks like a tube that now has a smaller flat base. The guide still works fine because the pressure of the mainspring holds it together, but I have to replace it and it will take some time to get one. Thankfully the rifle can still be assembled and tested.

Assembly and lubrication

The piston has to go into the rifle when the barrel is off the spring tube, so the cocking link will fit into the piston’s cocking slot. Of course the end of the cocking link gets moly grease as well as all the slots in the piston and spring tube where that link slides. Once the piston is all the way inside the spring tube the base block that holds the barrel can go back into the action forks of the spring tube. I lubed the two thin washers and the bushing that the pivot bolt passes through (see these parts in the Part 2 report) with moly grease.

Once the barrel is connected to the spring tube the new mainspring was lubed with Tune-in-a-Tube grease. To stay clean I lube the front half the spring coils then slide the spring into the piston to hold it while I put grease on the back half of the coils. Then the barreled action goes into the mainspring compressor to receive the trigger assembly and everything can be buttoned up. 

Buttoning up

This is the tricky part of the assembly, but the new mainspring made it easier because it’s shorter than the factory spring. That gave me more room to maneuver the action in the compressor.

To button up the 34’s powerplant two crosspins are pushed  through the spring tube and they pass through the trigger assembly. You can see the holes in the trigger assembly and spring tube here.

The tricky part is getting the two holes to line up all the way through the both sides of the spring tube and also the trigger assembly. I have found that putting the rear pin in first sometimes helps, but I have also put the front pin in first at times. When the holes align the pins will go through with finger pressure.

As you jockey the trigger assembly into place, watch the three crosspins in the trigger assembly. They are very loose and want to fall out, but putting them back can be difficult because spring tension in the assembly pushes the holes they pass through out of alignment.

I’m pushing the trigger assembly into the spring tube slowly. This kind of control is possible with a mainspring compressor. I can align the pin holes by pulling or pushing on the trigger to rotate the entire assembly at this point.

Stock on

After the barreled action is assembled, drop it into the stock. Don’t forget the plastic rear cap that the safety passes through. If you do, everything has to come out of the stock for a do-over.

How does she shoot?

The proof is in the shooting and cocking, so where did this spring and lube job get us? I want to take this down to the details, so here we go. On the first shot I noted that the cocking was almost as hard as previously, if not the same. BUT — there was no hesitation in the cocking stroke. I believe chamfering the entrance to the synthetic spring guide was what was needed. I still want to replace the guide, but after 4-5 shots it seems to work fine.

When fired…. wait for it.

The rifle now feels exactly like a Diana 34. Remember I told you that the bent mainspring was pressing against the inside of the piston and removing all the vibration. I said in Part 2 under the title Why so smooth?, “The mainspring is kinked on both ends and there are shiny silver spots on the outside of the coil where the spring has been pressing against the inside of the piston wall. That’s what kept the buzzing to a minimum. If the spring had been lubricated it would have been buzzier, not smoother, because the spring would have rattled around instead of pressing tight against the inner piston wall.”

I was right. This rifle now vibrates like all Diana 34s. I am not pleased with it at this point.

The cocking effort did diminish just a bit. For most of the stroke it takes 28 pounds to cock the rifle, but at one point the needle on the scale jumped up to 30 pounds, which is identical to what it was when I started the test. So the lube did smooth things a little (I think) but it’s not that much lighter like I hoped.

Where next?

We need a new spring guide for sure. That is what made the rifle difficult to cock — not a broken mainspring. I want to shoot this rifle more before I test it for velocity because right now it has detonated once in 4 shots. I want to try it with heavier pellets and see if it calms down. I may retest the cocking effort, as well

I like the new spring, but I will not tolerate vibration, so something’s got to change. I guess we learn what that is in the next report.

Tom Gaylord (B.B. Pelletier)

Tom Gaylord, also known as B.B. Pelletier, provides expert insights to airgunners all over the world on behalf of Pyramyd AIR. He has earned the title The Godfather of Airguns™ for his contributions to the industry, spending many years with AirForce Airguns and starting magazines dedicated to the sport such as Airgun Illustrated.

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