Tuesday, June 10, 2008

Diana Model 5 Disassembly, Part 2

And on we go...

The piston link was pulled forward and out of the slot.

The piston link.

The trigger adjustment screw (with ball) and locking screw. The trigger screw has a setscrew inside that adjusts the position of the ball relative to the screw...

The sight was removed. One screw was missing. We'll see if I can make a replacement.

The action was clamped in the spring compressor and the locking screw removed.

A strap wrench was used to unscrew the cap, keeping light pressure against it with the compressor. Unlike the Diana 6, the cap on the 5 holds the spring in. So it has force bearing against it.

The cap unscrewed fully and the compressor was unscrewed.

A spacer (which is interesting, I would have thought the spring would have taken up the full length of the tube) and the cap.

Spring guide, spacer, cap and the spring. There was a serious lack of any lubrication.

The piston was pushed out. I'd like to say "carefully", but I ended up skinning one finger on the sharp tube slot edge. Don't they have deburring tools in Germany?

The piston seal was in rough shape.

I'll have to make a replacement.

The dovetail button on the end of the piston.

All taken apart, I'll get it back together later this week.

28 comments:

Anonymous said...

Very detailed breakdown and pics. Thanks for the great work!
Any luck with that piston seal repair? I've used an oiled leather patch but not getting the results I had hoped for : (

Nick Carter said...

I ordered in some 95 durometer urethane rod to make a new piston seal out of, will probably be here in a day or two and we'll see if I can make a serviceable seal.

I think Maccari has seals for the 5, might be worth it to buy one.

Anonymous said...

What is the part number for the Diana 5 seals, you get from Maccari? Thanks for your help!

BeeKeeper

Anonymous said...

What is the part number for the Maccari seals? How about the spring, are you replacing it with Maccari?

Thanks!

BeeKeeper said...

Hi,

When you removed the end cap, what are you holding up the barrel with?

Can you display a few picture of how you removed the end cap? I have a exact gun I want to fix.

Where can I get the spring and the seals for this gun?

Thanks!

Nick Carter said...

Hi guys,
I got the Diana 6 seals from Air Rifle Headquarters/James Maccari

http://www.airguns.citymax.com/page/page/251327.htm

The seals are listed here:
http://www.airguns.citymax.com/catalog/item/251485/5087340.htm

I don't know if he has seals for the Diana 5 or not, and whether he has springs for the pistols.

But you can email him and ask, if anyone has them it's him.

Otherwise try Chambers in the UK:
http://www.gunspares.co.uk/shopdisplaycategories.asp?id=24035&cat=Diana%2FOriginal

Click on the model number of the pistol and see if they have what you need.

I held the gun in my spring compressor, which has a clamp to hold the action. I used a strap wrench (rubber) and my hands to unscrew it. I don't have any pictures of that specifically beyond what I showed.

Anonymous said...

You said that you held the gun in the spring compressor, which has a clamp to hold the action.

Can you show me how that is done? I am having trouble removing the end cap with the strap wrench.

I don't have a compressor, do you think I can fashion something quick to release the tension of the spring?

Thanks!

Nick Carter said...

You need to search and find some designs for spring compressors, get on the airgun forums, there are some easy to make designs out there. The yellow forum is likely the best place to start.

If the strap wrench won't loosen the end cap, then put some aluminum or copper sheet around the cap and use pump pliers or vise grips. just make sure the jaws don't bite through the sheet and mar the cap.

Anonymous said...

Hi Nick,

BTW, I used two of the blue belt wrenches that you used shown in the photo. Both of the belts were damaged under the strain, the belts were ripped apart under the strong tension.

I then followed your suggestion on wrapping a thin copper sheet around the cap and use a pipe wrench to turn the cap. It finally budged using the pipe wrench. It worked great! It did not mar the cap using this method. Thanks for your suggestion! I don't think there is any other ways to loosen this cap unless this method is used!

Thank you for your suggestion. You are a Pro!

Regards,

BeeKeeper

Anonymous said...

Can you tell me the technique you use to install the seal on the Diana 5?

The sharp wedge shape seems difficult to install the seal without cutting throgh the seal.

Do you heat up the seal to soften it before the installaing of the seal?

Thanks!

Nick Carter said...

I think I am so traumatized by it that I forgot to mention it in the post. I tried a number of things but what worked was hooking one side then using a smooth screwdriver like a shoehorn to stretch it on. It still took a number of tries, and I worried that I'd ruin it.

Oddly I was able to get the model 6 seals on by just pressing really hard against a flat surface.

Anonymous said...

Repair suggestions requested:
I bought my model 5 new in Germany in the late '60's and have not shot it for at least 30 years. It was never much used, was properly stored and lubricated, and appears to be in like-new condition. However, now it doesn't have enough power to expel a pellet out the barrel. Is this something that some gun oil down the air tube and a bit of soak time will take care of or does it mean replacing the piston seal or other repair?
Thanks,
Jim

Nick Carter said...

Jim,
As far as I know it always used synthetic seals, so oil won't help.
You probably have to replace the seals. As you've seen from the article, disassmbly is straighforward, but not that much fun. You can probably send it to an airgunsmith for resealing as well.

It could also be that the spring is tired or the breech seal is shot, but it's probably the piston seal...

Anonymous said...

Thanks for the feedback Nick. I have never overhauled a gun but have a small shop and could probably come up with a spring compressor. I have thus far been unable to locate a source parts or an air gunsmith in case I need to go that route. Any such information would be most appreciated.
Jim

Nick Carter said...

Jim,
Air Rifle Headquarters may have the seal, and you can always try Umarex who imports diana products.
Also Chambers Gunmakers in the UK.

As for finding an airgunsmith, I can't really recommend any as I haven't tried them but a search and or post requesting opinions of the Yellow Airgun forum should net some leads.

Anonymous said...

Hi Jim,

I have the same gun. Never shot it much for 30 years. The seal is crumbled to dust when I opened mine. You need to clean it and replace it. I got my parts from JM. Just tell them the model, he can get the parts for you. Great parts from JM. Good luck!

nagant army said...

My piston keeps locking up when I cock the gun it clicks but won't stay in place any advice?

Felice Luftschein said...

nagant army,
Either the sear is worn (bad), the sear interface is dirty and full of crud, or the trigger is adjusted too light.

nagant army said...

i managed after some serious work and pulling to get the piston out and well there was no seal i dont know what happened to it but its gone i got a new one from air gun headquarters and will be installing it soon what kind of lubrication should i put on this?

Felice Luftschein said...

Lube? It depends as there are a bunch of theories on the subject. Generally a very light smear of moly lube beind the head on the sides of the seal and on the piston major OD, and then your favorite spring grease for the spring, Possibly some lube on the chamber walls, but not too much. Basically just enough to avoid metal to metal contact.

nagant army said...

is there anywhere that you know of that i can find a diana model 5 piston or the dimensions to machine a new head? i thought the piston head was in better shape until i had the seal ready to be put on it its shot someone (me included) fired it without the piston seal there because they didnt know so i could use some help

Felice Luftschein said...

Possibly JG Airguns (US) or Chambers Gunmakers (UK). You should probably ask on the yellow airgun forum for other suggestions as well.
Nick

Azgulch said...

Can anyone tell me how to insert the piston with NEW piston seal into the cylinder of a Diana Model 5 pistol. The seal was obtained from Maccari but seems slightly too large to insert without damaging its edges against the cylinder edge. How can I get the piston into the cylinder without damaging the seal. Will a heat gun help?

Also, where does the long end of the trigger spring go when the gun is reassembled.

Easy to disassemble but reassembly not so easy but probably possible. Frustrating!

Felice Luftschein said...

You just have to sort of fit it in by compressing the lips as you insert it in the tube and past any cutouts. I usually use a thin dowel/chopstick to press the seal lip in.

Dean Speidel said...

If your Diana 5 or 5G's seal is missing when you open it up, look closely at the end (front) of the spring tube. My seal had come off the piston and was wedged at the bottom of the spring tube. You'll need some really long seal,picks to hook it out. Bad things happen if you put it back together without removing it.

Dean Speidel said...

If your Diana 5 or 5G's seal is missing when you open it up, look closely at the end (front) of the spring tube. My seal had come off the piston and was wedged at the bottom of the spring tube. You'll need some really long seal,picks to hook it out. Bad things happen if you put it back together without removing it.

Dean Speidel said...

I have a late 1950's Diana Model 5 that was unfortunately abused. I've managed to repair all the abuse, install a new piston and seal, and put it back together. However, when I try to cock it it won't "catch". Any suggestions on what might be the problem?

Nick Carter said...

If it won't catch then something is preventing the sear from engaging. Check that everything is pivoting smoothly in the trigger group and that the piston is moving backwards enough. Also check that the sear spring isn't too soft. The sear on teh piston could have become worn as well, which would be bad.