A picture of the updated Diana piston with the new crimp.

[look no hands]

If the groove in the piston rod is where the original crimp is then the second crimp is likely to make it more unstable
Stupid Idea I reckon !
( hope I don't have to explain )

I think it's a pretty bad idea in the first place using a crimps to hold the whole thing together, would the deeper crimps and the new crimps make the piston even more out of round? (yet another problem they've had) surely they should realise that the metal has to go somewhere when it gets compressed and it doesn't always go inwards.

Pete

[robs5230]

I really wish I hadn't seen that Barry.

After turning god knows how many rifles out with iffy pistons, they've now decided they need to crimp them a little harder ??

Looks like someone on work experience has "had a go"

On the list of top ten attempts to bodge a cure, this has pipped HW's 99"cure" by a fair margin.

Certainly put the lid on me owning another Diana.

[look no hands]

I really wish I hadn't seen that Barry.

After turning god knows how many rifles out with iffy pistons, they've now decided they need to crimp them a little harder ??

Looks like someone on work experience has "had a go"

On the list of top ten attempts to bodge a cure, this has pipped HW's 99"cure" by a fair margin.

Certainly put the lid on me owning another Diana.

My thoughts exactly, I think my 34 may be getting sold soon.

Pete

[robs5230]

My thoughts exactly, I think my 34 may be getting sold soon.

Pete

Yep.
I may offload mine now.
We may have to be quick though

[Barryg]

Yep.
I may offload mine now.
We may have to be quick though

So does this mean that both you and Pete would sell guns that you suspect are dangerous


There is something that was said by the owner of the piston in the pic, he said was that it was Umarex who sent him the piston and I was wondering if it was Umarex that done the bodge not Diana, we still don't know for sure how the stem is fixed in.

I don't think that we can compare this bodge with the 99 bodge because the 99 is a budget gun and these 52 pistons are in the 48/52/54/56/460/470/k98 and more just look at the price of a 56 and compare it with the 99 price

I think that a email to Diana is required to try to get some accurate info

[look no hands]

So does this mean that both you and Pete would sell guns that you suspect are dangerous


There is something that was said by the owner of the piston in the pic, he said was that it was Umarex who sent him the piston and I was wondering if it was Umarex that done the bodge not Diana, we still don't know for sure how the stem is fixed in.

I don't think that we can compare this bodge with the 99 bodge because the 99 is a budget gun and these 52 pistons are in the 48/52/54/56/460/470/k98 and more just look at the price of a 56 and compare it with the 99 price

I think that a email to Diana is required to try to get some accurate info

I've been meaning to sell my 34 for ages as I just don't use it and I could do with the money to either buy more BSA's or spend it on the ones I already have

It still doesn't instil any confidence in me when last year I had the sear snap and now this problem, fair enough mine isn't wobbly or come away yet but I have had it happen on a Chinese copy.

Just because the cost of the Diana's you've mentioned are far higher than the 99 doesn't mean they are built any better or with superior materials, Diana's have always been expensive in this country and that's down to the importers charging a fortune for them and that's why there's hardly any market for them.

Pete

[prosport.177]

I guess on the up side Diana have made it easier for the shed tuners to tinker with the Diana as it looks like the rods come out easy!!!
Hum which is worse I wonder the hw77 cocking arm cracking and letting go, or the Diana rod coming out!!

[Barryg]

I've been meaning to sell my 34 for ages as I just don't use it and I could do with the money to either buy more BSA's or spend it on the ones I already have

It still doesn't instil any confidence in me when last year I had the sear snap and now this problem, fair enough mine isn't wobbly or come away yet but I have had it happen on a Chinese copy.

LOL thats even worse you are prepared to sell a gun with two suspected dangers i'm not sure how many suspected dangers Robs thinks there might be but he says he might be unloading his Diana quickly that doesn't instill confidence in me buying S/H,
I don't think anyone should sell a gun if they suspect its safety this piston thing needs to be resolved because the rest of the gun is the best

BTW im not sure how, say a TX piston would handle the stresses that the diana's have to put up with in America with some of the huge springs that are crammed into them, this is why Diana's are so robust.

[robs5230]

So does this mean that both you and Pete would sell guns that you suspect are dangerous


There is something that was said by the owner of the piston in the pic, he said was that it was Umarex who sent him the piston and I was wondering if it was Umarex that done the bodge not Diana, we still don't know for sure how the stem is fixed in.

I don't think that we can compare this bodge with the 99 bodge because the 99 is a budget gun and these 52 pistons are in the 48/52/54/56/460/470/k98 and more just look at the price of a 56 and compare it with the 99 price

I think that a email to Diana is required to try to get some accurate info

I have no reason to suspect my Diana's are dangerous . I've had the pistons out of the rifles on all 3 to true up the out of round front end. All 3 have solidly fixed rods that are fixed true.
At least I know mine are good for certain (at this point in time anyway).

Do you therefore mean in light of this, no one should sell a used Diana ? Or maybe even a new one ? How many out there have loose rods is anyone's guess.

I'm unlikely to be rushing into selling mine ( well maybe one of the K's as I have 2 the same). The comment about getting rid was tongue in cheek.
However, the likelihood of me buying another is very slim.

[bozzer]

I very much doubt the piston rod is longer. That would mean reworking one of the major parts in this assembly. They clearly have no intention in doing that.

They are mass producing these things to a minimum cost or there would have gone more effort into this than smashing them all together with a load of pressure.

It looks like they have realised that some problems have arisen re loose rods and the odd rod coming out. So the answer is to give it a second smash together.

Not engineering purity ... but if it works it works. They aren't looking to flog Olympic Match accuracy here in these type of rifles. Just mass produced samples that will give most of the world decent enough power from a simple break barrel airgun to pop some tins in the garden or some bushy tails in the trees out to about 40 yards.

Unlike the 'Tune them to the Nth to squeeze another 3% accuracy out of them' brigade on here ... Diana aren't interested in that.

A 2 lb hammer knocks nails in. It doesn't have to be engineered to a tolerance of 0.001". It doesn't have to be Gold plated. You just want it to knock nails in and the head doesn't fly off and kill the bloke behind you. If this extra crushing fixes the safety issue ... it's sorted.

[jonnyone]

I very much doubt the piston rod is longer. That would mean reworking one of the major parts in this assembly. They clearly have no intention in doing that.

They are mass producing these things to a minimum cost or there would have gone more effort into this than smashing them all together with a load of pressure.

It looks like they have realised that some problems have arisen re loose rods and the odd rod coming out. So the answer is to give it a second smash together.

Not engineering purity ... but if it works it works. They aren't looking to flog Olympic Match accuracy here in these type of rifles. Just mass produced samples that will give most of the world decent enough power from a simple break barrel airgun to pop some tins in the garden or some bushy tails in the trees out to about 40 yards.

Unlike the 'Tune them to the Nth to squeeze another 3% accuracy out of them' brigade on here ... Diana aren't interested in that.

A 2 lb hammer knocks nails in. It doesn't have to be engineered to a tolerance of 0.001". It doesn't have to be Gold plated. You just want it to knock nails in and the head doesn't fly off and kill the bloke behind you. If this extra crushing fixes the safety issue ... it's sorted.

Very nicely put and makes perfect sense....

[Phil Russell]

So ... is there now a market for an 'aftermarket' piston pinning service?

Could it be done by drilling through then fixing a hardened steel pin in place? ... just in case?
Cheers, Phil

[robs5230]

So ... is there now a market for an 'aftermarket' piston pinning service?

Could it be done by drilling through then fixing a hardened steel pin in place? ... just in case?
Cheers, Phil

I don't think I'd be tempted to go that route Phil. A 10mm piston rod with a perfectly centred pin of say 3mm diameter leaves little enough rod either side.
Maybe on an unstressed, round piston but these are neither.

I reckon pinning may cause failure sooner than leaving as is.
Did you see the pic of the rod that snapped earlier in the thread ?

As commented in one of the earlier posts, I reckon the issues will be more apparent with our power hungry friends from over the pond.
A 52 doing in excess of 24ft/lbs experiences rather more shock than one ticking over at 11.

[Drew451]

I've never experienced piston/rod failure on any Diana Ive owned going back to 1986. I have had probably over a dozen Dianas with this method of piston construction and experienced varying degrees of out of roundness, which is annoying enough, but nothing more serious.
I believe that there have been big variations in the hardness of Diana piston etc. steel over quite a number of years. The steel obviously reacts differently to the pressures of crimping. This is how the out of round issue effects some guns much worse than others. And probably why there has instances of rod detachment.
Obviously, there is a happy medium that Diana have found the vast majority of the time. But you can't help thinking they should revert back to their old system or use a new method.
It would probably restore confidence which is critical. Especially at this juncture.

[bozzer]

With respect ...

They are probably more interested in their sales figures, and profits, at board meetings than a few posts from a few owners on internet boards who would ideally love the pistons to be fully machined and perfectly round.