HW35 Fettling

[TonyL]

Thanks Tony...

No problem; good luck with the project.

[TonyL]

Thats funny my 35e & my current bitza 35 made full power with just a service & relube, both on old leather washers, the bitza 79 action running a piston & seal from the mid 60's ! (both .22)

In my experience, the older '35 will make power easily as long as they don't have the porous breech brazing, breech seal okay and piston seal is sound and not too tight nor too loose.

[Waddy]

When you get the chance, definitely worth pulling it to bits then, Paul, and having a look.

If it's 25mm it might be using a parachute seal?

Obviously, the 'O' ring route can be chosen for any bore size, as they're easily and cheaply available. Be interesting to know what's inside.

If it's reduced and revolving it could well be fitted with a TX or Walther LGV piston as both of these have revolving pistons, in which case folks normally use them with a TX, Walther or Weihrauch 25mm seal.

Bigtoe/Tony Leach converted a few 80s like this a few years ago using Walther LGV pistons --- from memory he had to use a cut down new type cocking shoe to get clearance, so if you take the stock off you could look at the cocking shoe to see if it's one of his.

Venom also did a reduced cylinder HW80 but I'm not sure if they had rotating pistons or not ?





All the best Mick

Well, after that I had to pull it apart I now know why it's under powered, the spring has broken, about a coil and half from the trigger end. The spring guide is welded on, so the new spring has to fit that, fortunately I have a brand new Ox spring in my spring box that fits the guide, top hat and piston

I think the piston is a Walther one with a TX seal (looks a bit knackered) after looking at this. Only my piston is drilled & has concentric rings machined into it at the seal end. The trigger end glide band is 29mm so isn't doing anything.

The piston is 177mm long with it's short seal & weighs in at 250 grams.

The TP is 3mm

[T 20]

Ah, just remembered, the TX latchrod is flat faced on the rear, the Walther latchrod has a small central dome.

[TonyL]

Well, after that I had to pull it apart I now know why it's under powered, the spring has broken, about a coil and half from the trigger end. The spring guide is welded on, so the new spring has to fit that, fortunately I have a brand new Ox spring in my spring box that fits the guide, top hat and piston

I think the piston is a Walther one with a TX seal (looks a bit knackered) after looking at this. Only my piston is drilled & has concentric rings machined into it at the seal end. The trigger end glide band is 29mm so isn't doing anything.

The piston is 177mm long with it's short seal & weighs in at 250 grams.

The TP is 3mm

Nice and easy diagnosis then, Paul, and great that you have a spring that will fit. Strange that the rear glide is undersized. Or what I'd guess is undersized (I've never pulled a glided one apart, other than a standard TX) and I guess that light contact would be desirable? The gurus will know best. Imagine how lovely this thing's going to be once those little bits are taken care of.

[Shed tuner]

could you fit a larger band to the rear skirt to take up the excess clearance ?

[Waddy]

Ah, just remembered, the TX latchrod is flat faced on the rear, the Walther latchrod has a small central dome.

It has, far more than in that picture. I'll try to put a pic up.

Nice and easy diagnosis then, Paul, and great that you have a spring that will fit. Strange that the rear glide is undersized. Or what I'd guess is undersized (I've never pulled a glided one apart, other than a standard TX) and I guess that light contact would be desirable? The gurus will know best. Imagine how lovely this thing's going to be once those little bits are taken care of.

I think the rear was left as it was because the welded spring guide is doing that job to a degree. The rear glide is black & the front is white

could you fit a larger band to the rear skirt to take up the excess clearance ?

That's what I was thinking. There's a chap who's done me a bit of that sort of thing that I'll contact.




Ha ! managed to post a pic

[T 20]

Ha ! managed to post a pic

Kin hell --- that's not a piston, it's the exhaust baffle out of a Yam FS1E.

[Waddy]

Kin hell --- that's not a piston, it's the exhaust baffle out of a Yam FS1E.

A purple one with pedals that once belonged to Buck Rogers






.

[Shed tuner]

is that a red bull piston sleeve ?

[Waddy]

is that a red bull piston sleeve ?

It certainly is




.

[TonyL]

Kin hell --- that's not a piston, it's the exhaust baffle out of a Yam FS1E.

Wow! I can't view that image on this ageing I-Pad I'm using at home but I could view it on my phone when looking in at work whilst on break yesterday. Blimey, there's been some serious attention on that piston with the drill hasn't there?

Recoil should be low with the right spring set-up.

[Waddy]

Wow! I can't view that image on this ageing I-Pad I'm using at home but I could view it on my phone when looking in at work whilst on break yesterday. Blimey, there's been some serious attention on that piston with the drill hasn't there?

Recoil should be low with the right spring set-up.

It's not lost much weight because the metal is very thin, it's 250g VS 252g on a standard one according to that image I found. The front section with the concentric bands is solid metal, ie way more metal up front than on other pistons.

I'm having second thoughts about using the Ox spring, I think it could be a bit brutal.


.

[TonyL]

The extra weight towards the front of the piston with it being solid probably explains the extensive surgery further rearward then, Paul.

Mick has plenty of positive experiences with the Ox spring, but probably with bigger bore guns. There should be a half decent choice of softer springs to consider if you decide not to use the Ox.

[TonyL]

How wide is the spring guide, Paul?
Piston ID and rod diameter?